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64. Agriculture and Natural Resources Based Industries

64. Agriculture and Natural Resources Based Industries (34)

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64. Agriculture and Natural Resources Based Industries

Chapter Editor: Melvin L. Myers


Table of Contents

Tables and Figures

General Profile
Melvin L. Myers

     Case Study: Family Farms
     Ted Scharf, David E. Baker and Joyce Salg

Farming  Systems

Plantations
Melvin L. Myers and I.T. Cabrera

Migrant and Seasonal Farmworkers
Marc B. Schenker

Urban Agriculture
Melvin L. Myers

Greenhouse and Nursery Operations
Mark M. Methner and John A. Miles

Floriculture
Samuel H. Henao

Farmworker Education about Pesticides: A Case Study
Merri Weinger

Planting and Growing Operations
Yuri Kundiev and V.I. Chernyuk

Harvesting Operations
William E. Field

Storing and Transportation Operations
Thomas L. Bean

Manual Operations in Farming
Pranab Kumar Nag

Mechanization
Dennis Murphy

     Case Study: Agricultural Machinery
     L. W. Knapp, Jr.

Food  and Fibre Crops

Rice
Malinee Wongphanich

Agricultural Grains and Oilseeds
Charles Schwab

Sugar Cane Cultivation and Processing
R.A. Munoz, E.A. Suchman, J.M. Baztarrica and Carol J. Lehtola

Potato Harvesting
Steven Johnson

Vegetables and Melons
B.H. Xu and Toshio Matsushita   


Tree,  Bramble and Vine Crops

Berries and Grapes
William E. Steinke

Orchard Crops
Melvin L. Myers

Tropical Tree and Palm Crops
Melvin L. Myers

Bark and Sap Production
Melvin L. Myers

Bamboo and Cane
Melvin L. Myers and Y.C. Ko

Specialty  Crops

Tobacco Cultivation
Gerald F. Peedin

Ginseng, Mint and Other Herbs
Larry J. Chapman

Mushrooms
L.J.L.D. Van Griensven

Aquatic Plants
Melvin L. Myers and J.W.G. Lund

Beverage Crops

Coffee Cultivation
Jorge da Rocha Gomes and Bernardo Bedrikow

Tea Cultivation
L.V.R. Fernando

Hops
Thomas Karsky and William B. Symons

Health  and Environmental Issues

Health Problems and Disease Patterns in Agriculture
Melvin L. Myers

     Case Study: Agromedicine
     Stanley H. Schuman and Jere A. Brittain

Environmental and Public Health Issues in Agriculture
Melvin L. Myers

Tables

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1. Sources of nutrients
2. Ten steps for a plantation work risk survey
3. Farming systems in urban areas
4. Safety advice for lawn & garden equipment
5. Categorization of farm activities
6. Common tractor hazards & how they occur
7. Common machinery hazards & where they occur
8. Safety precautions
9. Tropical & subtropical trees, fruits & palms
10. Palm products
11. Bark & sap products & uses
12. Respiratory hazards
13. Dermatological hazards
14. Toxic & neoplastic hazards
15. Injury hazards
16. Lost time injuries, United States, 1993
17. Mechanical & thermal stress hazards
18. Behavioural hazards
19. Comparison of two agromedicine programmes
20. Genetically engineered crops
21. Illicit drug cultivation, 1987, 1991 & 1995

Figures

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65. Beverage Industry

65. Beverage Industry (10)

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65. Beverage Industry

Chapter Editor: Lance A. Ward


Table of Contents

Tables and Figures

General Profile
David Franson

Soft Drink Concentrate Manufacturing
Zaida Colon

Soft Drink Bottling and Canning
Matthew Hirsheimer

Coffee Industry
Jorge da Rocha Gomes and Bernardo Bedrikow

Tea Industry
Lou Piombino

Distilled Spirits Industry
R.G. Aldi and Rita Seguin

Wine Industry
Alvaro Durao

Brewing Industry
J.F. Eustace

Health and Environmental Concerns
Lance A. Ward

Tables

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1. Selected coffee importers (in tonnes)

Figures

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66. Fishing

66. Fishing (10)

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66. Fishing

Chapter Editors: Hulda Ólafsdóttir and Vilhjálmur Rafnsson


Table of Contents

Tables and Figures

General Profile
Ragnar Arnason

     Case Study: Indigenous Divers
     David Gold

Major Sectors and Processes
Hjálmar R. Bárdarson

Psychosocial Characteristics of the Workforce at Sea
Eva Munk-Madsen

     Case Study: Fishing Women

Psychosocial Characteristics of the Workforce in On-Shore Fish Processing
Marit Husmo

Social Effects of One-Industry Fishery Villages
Barbara Neis

Health Problems and Disease Patterns
Vilhjálmur Rafnsson

Musculoskeletal Disorders Among Fishermen and Workers in the Fish Processing Industry
Hulda Ólafsdóttir

Commercial Fisheries: Environmental and Public Health Issues
Bruce McKay and Kieran Mulvaney

Tables

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1. Mortality figures on fatal injuries among fishermen
2. The most important jobs or places related to risk of injuries

Figures

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67. Food Industry

67. Food Industry (11)

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67. Food Industry

Chapter Editor: Deborah E. Berkowitz


Table of Contents

Tables and Figures

Overview and Health Effects

Food Industry Processes
M. Malagié, G. Jensen, J.C. Graham and Donald L. Smith

Health Effects and Disease Patterns
John J. Svagr

Environmental Protection and Public Health Issues
Jerry Spiegel

Food Processing Sectors

Meatpacking/Processing
Deborah E. Berkowitz and Michael J. Fagel

Poultry Processing
Tony Ashdown

Dairy Products Industry
Marianne Smukowski and Norman Brusk

Cocoa Production and the Chocolate Industry
Anaide Vilasboas de Andrade

Grain, Grain Milling and Grain-Based Consumer Products
Thomas E. Hawkinson, James J. Collins and Gary W. Olmstead

Bakeries
R.F. Villard

Sugar-Beet Industry
Carol J. Lehtola

Oil and Fat
N.M. Pant

Tables

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1. The food industries, their raw materials & processes
2. Common occupational diseases in the food & drink industries
3. Types of infections reported in food & drink industries
4. Examples of uses for by-products from the food industry
5. Typical water reuse ratios for different industry sub-sectors

Figures

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68. Forestry

68. Forestry (17)

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68. Forestry

Chapter Editor: Peter Poschen


Table of Contents

Tables and Figures

General Profile
Peter Poschen

Wood Harvesting
Dennis Dykstra and Peter Poschen

Timber Transport
Olli Eeronheimo

Harvesting of Non-wood Forest Products
Rudolf Heinrich

Tree Planting
Denis Giguère

Forest Fire Management and Control
Mike Jurvélius

Physical Safety Hazards
Bengt Pontén

Physical Load
Bengt Pontén

Psychosocial Factors
Peter Poschen and Marja-Liisa Juntunen

Chemical Hazards
Juhani Kangas

Biological Hazards among Forestry Workers
Jörg Augusta

Rules, Legislation, Regulations and Codes of Forest Practices
Othmar Wettmann

Personal Protective Equipment
Eero Korhonen

Working Conditions and Safety in Forestry Work
Lucie Laflamme and Esther Cloutier

Skills and Training
Peter Poschen

Living Conditions
Elías Apud

Environmental Health Issues
Shane McMahon

Tables

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1. Forest area by region (1990)
2. Non-wood forest product categories & examples
3. Non-wood harvesting hazards & examples
4. Typical load carried while planting
5. Grouping of tree-planting accidents by body parts affected
6. Energy expenditure in forestry work
7. Chemicals used in forestry in Europe & North America in the 1980s
8. Selection of infections common in forestry
9. Personal protective equipment appropriate for forestry operations
10. Potential benefits to environmental health

Figures

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69. Hunting

69. Hunting (2)

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69. Hunting

Chapter Editor: George A. Conway


Table of Contents

Tables

A Profile of Hunting and Trapping in the 1990s
John N. Trent

Diseases Associated with Hunting and Trapping
Mary E. Brown

Tables

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1. Examples of diseases potentially significant to hunters & trappers

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70. Livestock Rearing

70. Livestock Rearing (21)

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70. Livestock Rearing

Chapter Editor: Melvin L. Myers


Table of Contents

Tables and Figures

Livestock Rearing: Its Extent and Health Effects
Melvin L. Myers

Health Problems and Disease Patterns
Kendall Thu, Craig Zwerling and Kelley Donham

     Case Study: Arthopod-related Occupational Health Problems
     Donald Barnard

Forage Crops
Lorann Stallones

Livestock Confinement
Kelley Donham

Animal Husbandry
Dean T. Stueland and Paul D. Gunderson

     Case Study: Animal Behaviour
     David L. Hard

Manure and Waste Handling
William Popendorf

     A Checklist for Livestock Rearing Safety Practice
     Melvin L. Myers

Dairy
John May

Cattle, Sheep and Goats
Melvin L. Myers

Pigs
Melvin L. Myers

Poultry and Egg Production
Steven W. Lenhart

     Case Study: Poultry Catching, Live Hauling and Processing
     Tony Ashdown

Horses and Other Equines
Lynn Barroby

     Case Study: Elephants
     Melvin L. Myers

Draught Animals in Asia
D.D. Joshi

Bull Raising
David L. Hard

Pet, Furbearer and Laboratory Animal Production
Christian E. Newcomer

Fish Farming and Aquaculture
George A. Conway and Ray RaLonde

Beekeeping, Insect Raising and Silk Production
Melvin L. Myers and Donald Barnard

Tables

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1. Livestock uses
2. International livestock production (1,000 tonnes)
3. Annual US livestock faeces & urine production
4. Types of human health problems associated with livestock
5. Primary zoonoses by world region
6. Different occupations & health & safety
7. Potential arthropod hazards in the workplace
8. Normal & allergic reactions to insect sting
9. Compounds identified in swine confinement
10. Ambient levels of various gases in swine confinement
11. Respiratory diseases associated with swine production
12. Zoonotic diseases of livestock handlers
13. Physical properties of manure
14. Some important toxicologic benchmarks for hydrogen sulphide
15. Some safety procedures related to manure spreaders
16. Types of ruminants domesticated as livestock
17. Livestock rearing processes & potential hazards
18. Respiratory illnesses from exposures on livestock farms
19. Zoonoses associated with horses
20. Normal draught power of various animals

Figures

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71. Lumber

71. Lumber (4)

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71. Lumber

Chapter Editors: Paul Demers and Kay Teschke


Table of Contents

Tables and Figures

General Profile
Paul Demers

Major Sectors and Processes: Occupational Hazards and Controls
Hugh Davies, Paul Demers, Timo Kauppinen and Kay Teschke

Disease and Injury Patterns
Paul Demers

Environmental and Public Health Issues
Kay Teschke and Anya Keefe

Tables

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1. Estimated wood production in 1990
2. Estimated production of lumber for the 10 largest world producers
3. OHS hazards by lumber industry process area

Figures

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72. Paper and Pulp Industry

72. Paper and Pulp Industry (13)

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72. Paper and Pulp Industry

Chapter Editors: Kay Teschke and Paul Demers


Table of Contents

Tables and Figures

General Profile
Kay Teschke

Major Sectors and Processes

Fibre Sources for Pulp and Paper
Anya Keefe and Kay Teschke

Wood Handling
Anya Keefe and Kay Teschke

Pulping
Anya Keefe, George Astrakianakis and Judith Anderson

Bleaching
George Astrakianakis and Judith Anderson

Recycled Paper Operations
Dick Heederik

Sheet Production and Converting: Market Pulp, Paper, Paperboard
George Astrakianakis and Judith Anderson

Power Generation and Water Treatment
George Astrakianakis and Judith Anderson

Chemical and By-product Production
George Astrakianakis and Judith Anderson

Occupational Hazards and Controls
Kay Teschke, George Astrakianakis, Judith Anderson, Anya Keefe and Dick Heederik

Disease and Injury Patterns

Injuries and Non-malignant Diseases
Susan Kennedy and Kjell Torén

Cancer
Kjell Torén and Kay Teschke

Environmental and Public Health Issues
Anya Keefe and Kay Teschke

Tables

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1. Employment & production in selected countries (1994)
2. Chemical constituents of pulp & paper fibre sources
3. Bleaching agents & their conditions of use
4. Papermaking additives
5. Potential health & safety hazards by process area
6. Studies on lung & stomach cancer, lymphoma & leukaemia
7. Suspensions & biological oxygen demand in pulping

Figures

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Thursday, 10 March 2011 14:37

Floriculture

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Since the early 1990s, in many countries and across several continents, floriculture as an economic activity has been expanding rapidly. Its growing importance in export markets has resulted in an integrated development of several aspects of this field of activity, including production, technology, scientific research, transportation and conservation.

Production

The production of cut flowers has two essential components:

  1. the process of production, which involves all activities directly related to the generation and the development of the product up to the moment of packing
  2. the various activities that aid in the production and promote the marketing and distribution of cut flowers.

 

The production process itself can be divided into three basic parts: germination, cultivation and post-harvest procedures.

Germination is carried out by planting parent plants from which cuttings are obtained for cultivation.

The cuttings of different flowers are planted on beds of a rooting medium. The beds are made from steam-treated dross and treated with chemical products to disinfect the growing medium and to facilitate root development.

Cultivation is done in greenhouses which house the beds of rooting medium where the flowers are planted and grown as discussed in the article “Greenhouse and nursery operations” in this chapter and as shown in figure 1. Cultivation includes preparing the soil, planting the cuttings (figure 2) and harvesting the flowers.

Figure 1. Tending flowers in a greenhouse

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Figure 2. Planting cuttings in a greenhouse

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Planting includes the cycle that begins with placing the cuttings in the rooting medium and ends with the flowering plant. It includes the following activities: planting, normal irrigation, drip irrigation with fertilizer, cultivation and weeding of the soil, pinching the tip of the plants to force branching and obtain more flowers, preparing the props that hold the plants upright, and the growth, branching and flowering of the plant.

Production concludes with the gathering of the flowers and their separation by classification.

At the post-harvest stage—in addition to selection and classification—the flowers are covered with plastic hoods, a sanitary treatment is applied, and they are packed for shipment.

Secondary activities include monitoring the health of the plants to detect pests and to diagnose plant illnesses early, obtaining raw materials from the warehouse, and maintaining the furnaces.

Health Risk Factors

The most important risk factors in each of the different areas of work are:

  • chemical substances
  • extreme temperatures—heat
  • non-ionizing radiation
  • infectious disease
  • ergonomic factors
  • mechanical factors
  • psychosocial factors.

 

Chemical substances

Intoxication and chronic illness due to pesticides

The levels of morbidity/mortality found in workers due to exposure to pesticides are not the consequence of a simple relation between the chemical agent and the person who has suffered exposure to it, but also reflect the interplay of many other factors. Among these are the length of exposure, individual susceptibility, the nutritional state of the person exposed, educational and cultural variables and the socioeconomic conditions under which the workers live.

In addition to the active ingredients of pesticides, the substances that convey the active ingredients and the additives should also be taken into consideration, because sometimes those substances can have adverse effects that are more harmful than those of the active ingredients.

The toxicity of pesticides made with organophosphates is due to their effect on the central nervous system, because they inhibit the activity of the enzyme acetylcholinesterase. The effects are cumulative, and delayed effects have also been noted on the central and the peripheral nervous systems. According to studies carried out in several countries, the prevalence of inhibition of this enzyme among workers who handle these pesticides fluctuates between 3 and 18%.

The long-term effects are pathological processes that develop after a latency period and are due to repeated exposures. Among the long-term effects known to be due to pesticide exposure are skin lesions, nerve damage and mutagenic effects.

Respiratory problems

Decorative plants can irritate the respiratory system and cause coughing and sneezing. In addition, plant scents or odours may exacerbate symptoms of asthma or allergic rhinitis, although they have not been shown to cause allergies. Pollen from the chrysanthemum and the sunflower can cause asthma. Dust from dried plants sometimes causes allergies.

Dermatitis

The cases of occupational dermatitis found in floriculture are about 90% primarily due to contact dermatitis. Of these, about 60% are caused by primary irritants and 40% are due to allergic reactions. The acute form is characterized by reddening (erythema), swelling (oedema), pimples (papules), vesicles or blisters. It is especially localized on the hands, wrists and forearms. The chronic form can have deep fissures, lichenification (thickening and hardening) of the skin, and severe xerosis (dryness). It can be incapacitating and even irreversible.

Floriculture is one of those activities where contact with primary irritants or allergenic substances is high, and for that reason it is important to promote and use preventive measures, such as gloves.

Extreme temperatures—heat

When work must be carried out in a hot environment, as in the case of hothouses, the thermal load on the worker is the sum of the heat of the work environment plus the energy expended on the task itself.

Physical effects of excessive exposure to heat include heat rash, cramps and muscle spasms, exhaustion and fainting spells. Heat rash, in addition to being uncomfortable, lowers the worker’s tolerance to heat. If perspiration is abundant and liquids and electrolytes are not replenished adequately, cramps and muscle spasms can set in. Heat exhaustion occurs when vasomotor control and cardiac output are insufficient to compensate for the additional demands placed on these systems by the heat stress. Fainting spells represent a very serious clinical situation that can lead to confusion, delirium and coma.

Precautions include frequent rest breaks in cool areas, availability of beverages to drink, rotating of tasks requiring heavy exertion and wearing of light-coloured clothing.

Non-ionizing radiation

The most important kinds of non-ionizing radiation that floriculture workers are exposed to are ultraviolet (UV) radiation, visible light and infrared radiation. The most serious effects of UV radiation are solar erythema, actinic dermatitis, irritative conjunctivitis and photokeratitis.

Radiation from the visible spectrum of light may cause retinal and macular degeneration. One symptom of exposure to infrared radiation is superficial burn of the cornea, and prolonged exposure can lead to the premature appearance of cataracts.

Precautions include keeping the skin covered, wearing tinted glasses, and medical surveillance.

Ergonomic factors

Workers who maintain a static body posture for long periods of time (see figure 3) can suffer from resulting static muscle contractions and from alterations of the peripheral, vascular and nervous systems. Repetitive movements are more common in tasks that require manual dexterity. For example, clipping shears can require a lot of force and involve repetitive motion. The most frequently observed effects are musculoskeletal impairments, including tendinitis of the elbow and wrist, carpal tunnel syndrome and impairment of movement at the shoulder.

Figure 3. Bending over for extended periods is a common cause of ergonomic problems

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Job rotation and the proper ergonomic design of equipment such as clipping shears are needed precautions. Redesigning the workplace to require less bending is another solution.

Infectious diseases

Floriculture may expose workers to a variety of biological agents. Early signs of an infection are rarely specific, although they are generally well-defined enough to lead to a suspicion of illness. The signs, symptomatology and precautions depend on the agent, which includes tetanus, rabies, hepatitis and so on. Preventive measures include a source of potable water, good sanitary facilities, first aid and medical care for cuts and abrasions.

Other factors

The most common health and safety hazards associated with mechanical factors are cuts, abrasions and single and multiple traumas, which most frequently injure the hands and face. Such injuries must be attended to immediately. Workers should have up-to-date tetanus shots and adequate first-aid facilities must be available.

The psychosocial environment can also endanger worker health. The results of exposure to these factors can have the following consequences: physiological changes (indigestion, constipation, palpitations, difficulty breathing, hyperventilation, insomnia and anxiety); psychological disturbances (tension and depression); and behavioural disturbances (absenteeism, instability, dissatisfaction).

 

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Monday, 28 March 2011 20:15

Recycled Paper Operations

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The use of waste or recycled paper as the raw material for pulp production has increased during the last several decades, and some paper plants depend almost completely on waste paper. In some countries, waste paper is separated from other household waste at the source before it is collected. In other countries separation by grade (e.g., corrugated board, newsprint, high-grade paper, mixed) takes place in special recycling plants.

Recycled paper can be repulped in a relatively mild process which uses water and sometimes NaOH. Small metal pieces and plastics may be separated during and/or after repulping, using a debris rope, cyclones or centrifugation. Filling agents, glues and resins are removed in a cleaning stage by blowing air through the pulp slurry, sometimes with the addition of flocculating agents. The foam contains the unwanted chemicals and is removed. The pulp can be de-inked using a series of washing steps which may or may not include the use of chemicals (i.e., surfactant fatty acid derivatives) to dissolve remaining impurities, and bleaching agents to whiten the pulp. Bleaching has the disadvantage that it may reduce fibre length and therefore lessen final paper quality. The bleaching chemicals used in recycled pulp production are usually similar to those used in brightening operations for mechanical pulps. After the repulping and de-inking operations, sheet production follows in a manner very similar to that using virgin fibre pulp.

 

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At the San Antonio farm, several workers became poisoned when applying the pesticide Lannate. An investigation of the case revealed that the workers had been using backpack sprayers for application without wearing any protective clothing, gloves or boots. Their employer had never provided the necessary equipment, and soap and showers were also unavailable. Following the poisonings, the employer was directed to take the appropriate corrective actions.

When the Ministry of Health made a follow-up inspection, they discovered that many farmers were still not using any protective clothing or equipment. When they were asked why, some said that the equipment was too hot and uncomfortable. Others explained that they had been working this way for years and never had any problems. Several commented that they didn’t need the equipment because they drank a large glass of milk after applying pesticides.

This experience, which took place in Nicaragua, is common to many parts of the world and illustrates the challenge to effective farmworker training. Training must be accompanied by provision of a safe work environment and legislative enforcement, but must also consider the barriers to implementing safe work practices and incorporate them in training programmes. These barriers, such as unsafe work environments, absence of protective equipment and attitudes and beliefs which are not health-promoting, should be directly discussed in training sessions, and strategies to address them should be developed.

This article describes an action-oriented training approach applied in two multidisciplinary pesticide projects that were designed to address the problem of farmworker pesticide poisoning. They were implemented in Nicaragua by CARE, Nicaragua and the American Friends Service Committee (1985 to 1989) and in the Central American region by the International Labour Organization (ILO, 1993 to present). In addition to a strong educational approach, the Nicaraguan project developed improved methods to mix and load pesticides, a medical monitoring plan to screen workers for overexposure to pesticides and a system to collect data for epidemiological investigation (Weinger and Lyons 1992). Within its multifaceted project, the ILO emphasized legislative improvements, training and building a regional network of pesticide educators.

Key elements of both projects were the implementation of a training needs assessment in order to tailor teaching content to the target audience, the use of a variety of participatory teaching approaches (Weinger and Wallerstein 1990) and the production of a teacher’s guide and educational materials to facilitate the learning process. Training topics included the health effects of pesticides, symptoms of pesticide poisoning, rights, resources and a problem-solving component which analysed the obstacles to working safely and how to resolve them.

Although there were many similarities between the two projects, the Nicaraguan project emphasized worker education while the regional project focused on teacher training. This article provides selected guidelines for both worker and teacher training.

Worker Education

Needs assessment

The first step in developing the training programme was the needs assessment or “listening phase”, which identified problems and obstacles to effective change, recognized factors which were conducive to change, defined values and beliefs held by the farmworkers and identified specific hazardous exposures and experiences which needed to be incorporated into the training. Walkthrough inspections were used by the Nicaraguan project team to observe work practices and sources of worker exposure to pesticides. Photographs were taken of the work environment and work practices for documentation, analysis and discussion during the training. The team also listened for emotional issues which might be barriers to action: worker frustration with inadequate personal protection, lack of soap and water or lack of safe alternatives to currently used pesticides.

Training methods and objectives

The next step in the training process was to identify the content areas to be covered utilizing information gained from listening to workers and then to select appropriate training methods based on the learning objectives. The training had four objectives: providing information; identifying and changing attitudes/emotions; promoting healthy behaviours; and developing action/problem-solving skills. What follows are examples of methods grouped under the objective which they best achieve. The following methods were incorporated into a 2-day training session (Wallerstein and Weinger 1992).

Methods for information objectives

Flipchart. In Nicaragua, the project staff needed visual educational tools which were easily portable and independent of electricity for use during field training or with medical screening on the farms. The flipchart included 18 drawings based on real-life situations, which were designed for use as discussion starters. Each picture had specific objectives and key questions that were outlined in an accompanying guide for instructors.

The flipchart could be used both to provide information and to promote problem analysis leading to action planning. For example, a drawing was used to provide information on the routes of entry by asking “How do pesticides enter the body?” To generate analysis of the problem of pesticide poisoning, the instructor would ask participants: “What’s happening here? Is this scene familiar? Why does this occur? What can (he) you do about it?” The introduction of two or more people into a drawing (of two people entering a recently sprayed field) encourages discussion of suspected motivations and feelings. “Why is she reading the sign? Why did he go right in?” With effective visual images, the same picture may trigger a variety of discussions, depending upon the group.

Slides. Slides which portray familiar images or problems were used in the same way as the flipchart. Using photos taken during the needs assessment phase, a slide show was created following the path of pesticide use from selection and purchase to disposal and clean-up at the end of the workday.

Methods for attitude-emotion objectives

Attitudes and emotions may effectively block learning and influence how health and safety practices are implemented back on the job.

Scripted role-play. A scripted role-play was often used to explore attitudes and trigger discussion of the problems of exposure to pesticides. The following script was given to three workers, who read their roles to the entire group.

Jose: What’s the matter?

Rafael: I’m about ready to give up. Two workers were poisoned today, just one week after that big training session. Nothing ever changes around here.

Jose: What did you expect? The managers didn’t even attend the training.

Sara: But at least they scheduled a training for the workers. That’s more than the other farms are doing.

Jose: Setting up a training is one thing, but what about follow-up? Are the managers providing showers and adequate protective equipment?

Sara: Have you ever thought that the workers might have something to do with these poisonings? How do you know they’re working safely?

Rafael: I don’t know. All I know is that two guys are in the hospital today and I have to go back to work.

The role-play was developed to explore the complex problem of pesticide health and safety and the multiple elements involved in resolving it, including training. In the discussion which followed, the facilitator asked the group if they shared any of the attitudes expressed by the farmworkers in the role-play, explored obstacles to resolving the problems portrayed and solicited strategies for overcoming them.

Worksheet questionnaire. In addition to serving as an excellent discussion starter and providing factual information, a questionnaire can also be a vehicle for eliciting attitudes. Sample questions for a farmworker group in Nicaragua were:

1. Drinking milk before work is effective in preventing pesticide poisoning.

Agree            Disagree

2. All pesticides have the same effect on your health.

Agree            Disagree

 

A discussion of attitudes was encouraged by inviting participants with conflicting viewpoints to present and justify their opinions. Rather than affirming the “correct” answer, the instructor acknowledged useful elements in the variety of attitudes that were expressed.

Methods for behavioural skill objectives

Behavioural skills are the desired competencies that workers will acquire as a result of training. The most effective way to achieve objectives for behavioural skill development is to provide participants with opportunities to practise in the class, to see an activity and perform it.

Personal protective equipment demonstration. A display of protective equipment and clothing was laid out on a table in front of the class, including an array of appropriate and inappropriate options. The trainer asked a volunteer from the audience to get dressed for work applying pesticides. The farmworker chose clothing from the display and put it on; the audience was asked to comment. A discussion followed concerning appropriate protective clothing and alternatives to uncomfortable clothing.

Hands-on practice. Both trainers and farmworkers in Nicaragua learned to interpret pesticide labels by reading them in small groups during the class. In this activity, the class was divided into groups and given the task of reading different labels as a group. For low-literacy groups, volunteer participants were recruited to read the label aloud and lead their group through a worksheet questionnaire on the label, which emphasized visual cues to determine level of toxicity. Back in the large group, volunteer spokespeople introduced their pesticide to the group with instructions for potential users.

Methods for action/problem-solving objectives

A primary goal of the training session is to provide farmworkers with the information and skills to make changes back on the job.

Discussion starters. A discussion starter can be used to pose problems or potential obstacles to change, for analysis by the group. A discussion starter can take a variety of forms: a role-play, a picture in a flipchart or slide, a case study. To lead a dialogue on the discussion starter, there is a 5-step questioning process which invites participants to identify the problem, project themselves into the situation being presented, share their personal reactions, analyse the causes of the problem and suggest action strategies (Weinger and Wallerstein 1990).

Case studies. Cases were drawn from real and familiar situations that occurred in Nicaragua that were identified in the planning process. They most commonly illustrated problems such as employer noncompliance, worker noncompliance with safety precautions within their control and the dilemma of a worker with symptoms that may be related to pesticide exposure. A sample case study was used to introduce this article.

Participants read the case in small groups and responded to a series of questions such as: What are some of the causes of pesticide poisoning in this incident? Who’s benefiting? Who’s being harmed? What steps would you take to prevent a similar problem in the future?

Action planning. Prior to the conclusion of the training session, participants worked independently or in groups to develop a plan of action to increase workplace health and safety when pesticides are used. Using a worksheet, participants identified at least one step they could take to promote safe working conditions and practices.

Evaluation and Teacher Training

Determining the extent to which the sessions met their objectives is a crucial part of training projects. Evaluation tools included a written post-workshop questionnaire and follow-up visits to farms as well as surveys and interviews with participants 6 months following the training session.

Training teachers who would utilize the approach outlined above to provide information and training to farmworkers was an essential component of the ILO-sponsored Central American programmes. The objectives of the teacher training programme were to increase the knowledge on pesticide health and safety and the teaching skill of trainers; to increase the number and quality of training sessions directed toward farmworkers, employers, extension workers and agronomists in project countries; and to initiate a network of educators in pesticide health and safety in the region.

Training topics in the 1-week session included: an overview of the health effects of pesticides, safe work practices and equipment; the principles of adult education; steps in planning an educational programme and how to implement them; demonstration of selected teaching methods; overview of presentation skills; practice teaching by participants using participatory methods, with critique; and development of action plans for future teaching about pesticides and alternatives to their use. A 2-week session allows time to conduct a field visit and training needs assessment during the workshop, to develop educational materials in the classroom and to conduct worker training sessions in the field.

A trainer’s guide and sample curricula were provided during the workshop to facilitate practice teaching both in the classroom and following the workshop. The educators’ network offers another source of support and a vehicle for sharing innovative teaching approaches and materials.

Conclusion

The success of this teaching approach with workers in the cotton fields of Nicaragua, trade unionists in Panama and trainers from the Ministry of Health in Costa Rica, among others, demonstrates its adaptability to a variety of work settings and target groups. Its goals are not only to increase knowledge and skills, but also to provide the tools for problem-solving in the field after the teaching sessions have ended. One must be clear, however, that education alone cannot resolve the problems of pesticide use and abuse. A multidisciplinary approach which includes farmworker organizing, legislative enforcement strategies, engineering controls, medical monitoring and investigation into alternatives to pesticides is essential to effect comprehensive changes in pesticide practices.

 

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End products of pulp and paper mills depend on the pulping process, and may include market pulp and various types of paper or paperboard products. For example, the relatively weak mechanical pulp is converted into single-use products such as newspapers and tissue. Kraft pulp is converted into multi-use paper products such as high-quality writing paper, books and grocery bags. Sulphite pulp, which is primarily cellulose, can be used in a series of diverse end-products including specialty paper, rayon, photographic film, TNT, plastics, adhesives, and even ice cream and cake mixes. Chemi-mechanical pulps are exceptionally stiff, ideal for the structural support needed for corrugated container board. The fibres in pulp from recycled paper are usually shorter, less flexible and less water permeable, and can therefore not be used for high-quality paper products. Recycled paper is therefore mainly used for the production of soft paper products like tissue paper, toilet paper, paper towelling and napkins.

To produce market pulp, the pulp slurry is usually screened once more and its consistency adjusted (4 to 10%) before it is ready for the pulp machine. The pulp is then spread onto a travelling metal screen or plastic mesh (known as the “wire”) at the “wet end” of the pulp machine, where the operator monitors the speed of the moving wire and the water content of the pulp (figure 1; the presses and the cover of the drier can be seen in the upper left; in modern mills, operators spend a great deal of time in control rooms). Water and filtrate are drawn through the wire, leaving a web of fibres. The pulp sheet is passed through a series of rotating rolls (“presses”) that squeeze out water and air until the fibre consistency is 40 to 45%. The sheet is then floated through a multi-storey sequence of hot-air dryers until the consistency is 90 to 95%. Finally, the continuous pulp sheet is cut into pieces and stacked into bales. The pulp bales are compressed, wrapped and packaged into bundles for storage and transport.

Figure 1. Wet end of pulp machine showing fibre mat on the wire.

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Canfor Library

Although similar in principle to making pulp sheets, paper making is considerably more complex. Some mills use a variety of different pulps to optimize paper quality (e.g., a mix of hardwood, softwood, kraft, sulphite, mechanical or recycled pulps). Depending on the type of pulp used, a series of steps is necessary prior to forming the paper sheet. Generally, dried market pulp is rehydrated, while high-consistency pulp from storage is diluted. Pulp fibres may be beaten to increase the fibre-bonding area and thereby improve paper sheet strength. The pulp is then blended with “wet-end” additives (table 1) and passed through a final set of screens and cleaners. The pulp is then ready for the paper machine.

Table 1. Papermaking additives

Additive

Location applied

Purpose and/or examples of specific agents

Most commonly used additives

Talc

Wet end

Pitch control (prevent deposition and accumulation
of pitch)
Filler (make brighter, smoother, more opaque)

Titanium dioxide

Wet end

Pigment (brighten sheet, improve printing)
Filler (make brighter, smoother, more opaque)

“Alum”(Al2(SO4)3)

Wet end

Precipitates rosin sizing onto fibres
Retention aid (fix additives to fibres, improve pulp
fibre retention)

Rosin

Wet end

Internal sizing (resist liquid penetration)

Clay (kaolin)

Wet/dry

Filler (make brighter, smoother, more opaque)
Pigment or surface coating (impart colour)

Starch

Wet/dry

Surface sizing (resist liquid penetration)
Dry strength additive (increase strength, reduce
surface lint)
Retention aid (bind additives to paper, improve
pulp fibre retention)

Dyes and
pigments

Wet/dry

e.g., acid, basic or direct dyes,colour lakes,
CaCO3, may also include solvent vehicles

Latex

Dry end

Adhesive (reinforce sheet, bind additives to paper,
fill pores)
Waterproofing (resist liquid penetration)

Other additives

Slimicides

Wet end

e.g., thiones, thiazoles, thiocyanates, hiocarbamates, thiols, isothiazolinones,
formaldehyde, glutaraldehyde, glycols, naphthol,
chlorinated and brominated organics, organic
mercury compounds

Defoamers

Wet end

e.g., pine oil, fuel oil, recycled oils, silicones, alcohols

Wire treatment
agents

Wet end

e.g., imidazoles, butyl diglycol, acetone, turpentine,
phosphoric acid

Wet and dry
strength additives

Wet end

e.g., formaldehyde resins, epichlorohydrin, glyoxal,
gums, polyamines, phenolics,
polyacrylamides, polyamids, cellulose derivatives

Coatings,
adhesives and
plasticizers

Dry end

e.g., aluminium hydroxide, polyvinyl acetate,
acrylics, linseed oil, gums, protein glues, wax
emulsions, azite, glyoxal, stearates, solvents,
polyethylene, cellulose derivatives, foil, rubber
derivatives, polyamines, polyesters,
butadiene-styrene polymers

Others

Wet/dry

Corrosion inhibitors, dispersants, flameproofing,
antitarnish agents, drainage aids, deflocculants, pH
control agents, preservatives

 

The flow spreader and headbox distribute a thin suspension (1 to 3%) of refined pulp onto a moving wire (similar to a pulp machine, only at a much higher speed, sometimes in excess of 55 km/h) which forms the fibres into a thin felted sheet. The sheet moves through a series of press rolls to the dryer section, where a series of steam-heated rolls evaporate most of the remaining water. Hydrogen bonds between the fibres have fully developed at this stage. Finally, the paper is calendered and reeled. Calendering is the process by which the paper surface is ironed smooth and its thickness reduced. The dried, calendered paper sheet is wound onto a reel, labelled and transported to the warehouse (figure 2; note waste paper under reel, and unenclosed operator control panel). “Dry-end” additives can be added before calendering on the paper machine or in separate “off-machine” coating operations in the converting sector of the industry.

Figure 2. Dry end of a paper machine showing full paper reel and operator using air slitter to cut end.

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George Astrakianakis

A variety of chemicals are used in the papermaking process to provide the paper with specific surface characteristics and sheet properties. The most commonly used additives (table 1) are typically used at the per cent level, though some such as clay and talc may contribute as much as 40% to the dry weight of certain papers. Table 1 also indicates the diversity of chemical additives which may be used for specific production purposes and products; some of these are used at very low concentrations (e.g., slimicides are added to process water in parts per million).

The process of making paperboard is similar to that of making paper or pulp. A suspension of pulp and water is dispersed onto a travelling wire, the water is removed, and the sheet dried and stored as a roll. The process differs in the way that the sheet is formed to give thickness, in the combining of multiple layers, and in the drying process. Board can be made from single or multi-layered sheets with or without a core. The sheets are usually high-quality kraft pulp (or kraft and CTMP blend), while the core is made from either a blend of semi-chemical and low-cost recycled pulp or from entirely recycled pulp and other waste material. Coatings, vapour barriers and multiple layers are added according to the end use to protect the contents from water and physical damage.

 

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Thursday, 10 March 2011 14:44

Planting and Growing Operations

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Modern agriculture is based on highly efficient equipment, especially high-speed, powerful tractors and agricultural machines. Tractors with mounted and trailed implements allow the mechanization of many agricultural operations.

Use of tractors allows farmers to accomplish the main tillage and care of plants in the optimum time without major manual labour. Permanent enlargement of farms, extension of land under cultivation and intensification of crop rotation promotes more efficient agriculture as well. Widespread use of high-speed assemblies is hampered by two factors: existing agricultural methods based mainly on machines and implements with passive tools; and difficulties in ensuring safe working conditions for the high-speed tractor assembly operator.

Mechanization can accomplish approximately 70% of planting and growing operations. It is used at all stages of crop cultivation and harvesting as well. Nevertheless, each stage of planting and growing has its own requisite set of machines, tools and environmental conditions, and this variability of the production and environmental factors has an influence upon the tractor driver.

Cultivation of the Land

Cultivation of the land (ploughing, harrowing, scuffing, disk harrowing, entire cultivation, rolling-down) is important and the most labour-intensive preliminary stage of crop production. These operations involve 30% of planting and growing operations.

As a rule, loosening of the soil results in the formation of dust. The nature of the dust in the air is variable, and depends on meteorological conditions, season, kind of work, type of soil and so on. Dust concentration in tractor cabs can vary from a few mg/m3 to hundreds of mg/m3, depending essentially on the cab enclosure. Approximately 60 to 65% of cases exceed the permissible total dust concentration level; permissible levels of respirable (less than or equal to 5 microns) dust are exceeded 60 to 80% of the time (see figure 1). Silica content in the dust varies from 0.5 to 20% (Kundiev 1983).

Figure 1. Tractor driver exposures to dust during land cultivation

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Cultivation consists of power-consuming operations, especially during ploughing, and it demands a considerable mobilization of the power resources of machines, generating considerable levels of noise where tractor drivers sit. These noise levels amount to 86 to 90 dBA and higher, creating a considerable risk of hearing disorders for these workers.

As a rule, whole-body vibration levels where the tractor driver is seated can be very high, exceeding levels established by the International Organization for Standardization (ISO 1985) for fatigue-decreased proficiency boundary and frequently for exposure limit.

Ground preparation is conducted mainly in early spring and autumn, so the microclimate of cabs in temperate zones for machines without air conditioners is not a health problem except on occasional hot days.

Sowing and Growing

Ensuring that sowing attachments or ploughing implements move in a straight line and that tractors follow marker tracks or the middle of the row are characteristic features of the sowing and care of crops.

In general, these activities require the driver to work in uncomfortable positions and involve considerable nervous and emotional tension due to restricted working-zone visibility, resulting in rapid development of operator fatigue.

The layout of sowing machines and their preparation for use, as well as the necessity of manual auxiliary work, especially materials handling, may involve considerable physical loads.

A wide geographical distribution of grain varieties results in a diversity of meteorological conditions when sowing. Winter crop sowing for different climate zones can be performed, for example, when the outdoor temperature ranges from 3–10 °C to 30–35 °C. Spring crop sowings are performed when the outdoor temperature ranges from 0 °C to 15–20 °C. The temperatures in tractor cabs without air conditioners can be very high in regions where climate is mild and hot.

Microclimate conditions in tractor cabs are favourable as a rule during tilled crops sowing (sugar beet, maize, sunflower) in temperate zones. Cultivation of crops is performed when the outdoor temperature is high and solar radiation is intense. The air temperature in cabs without microclimate control can rise to 40 °C and more. Tractor drivers can work under uncomfortable conditions about 40 to 70% of the total time involved in the care of crops.

Working operations for tilled crops cultivation involve considerable moving of earth, causing formation of dust. Maximum ground dust concentrations in the breathing zone air do not exceed 10 to 20 mg/m3. The dust is 90% inorganic, containing a large amount of free silica. Noise and vibration levels where the driver sits are a little lower than those existing during cultivation.

During sowing and cultivation, workers can be exposed to manures, chemical fertilizers and pesticides. When safety regulations for handling these materials are not followed, and if machines are not working properly, the breathing zone concentration of hazardous materials can exceed permissible values.

Harvesting

As a rule, harvesting lasts from 25 to 40 days. Dust, microclimate conditions and noise can be hazards during harvesting.

Breathing zone dust concentrations depend chiefly on outside concentration and the airtightness of the harvesting machine’s cab. Older machines without cabs leave drivers exposed to the dust. Dust formation is most intensive during the harvesting of dry corn, when the dust concentration at non-enclosed combines’ cabs can be as much as 60 to 90 mg/m3. Dust consists mainly of plant scraps, pollen and mushroom spores, mostly in large, nonrespirable particles (larger than 10 microns). Free silica content is less than 5.5%.

Formation of dust during sugar beet harvesting is lower. Maximum dust concentration at the cab does not exceed 30 mg/m3.

Harvesting of grain is generally performed in the hottest season. Temperature in the cab can rise to 36 to 40 °C. The flux level of direct solar radiation is 500 W/m2 and more when ordinary glass is used for cab windows. Tinted glass lowers the temperature of air in the cab by 1 to 1.6 °C. A mechanical forced ventilation system with a flow rate of 350 m3/h can create a temperature difference between inside and outside air of 5 to 7 °C. If the combine is equipped with adjustable louvers, this difference drops to 4 to 6 °C.

Tilled crops are harvested in the autumn months. As a rule conditions of the microclimate in cabs in this time are not a great health problem.

Experience in developed countries points to the fact that agriculture at small farms can be profitable with the use of small-scale mechanization (minitractors—motorized units with a capacity of up to 18 horsepower, with different kinds of auxiliary equipment).

Use of such equipment gives rise to a number of specific health problems. These problems include: intensification of workload in certain seasons, the use of child labour and the labour of elderly persons, absence of the means of protection against intensive noise, whole-body and local vibration, harmful meteorological conditions, dust, pesticides, and exhaust gases. The effort necessary to move the control levers of motorized units can amount to 60 to 80 N (newtons).

Some kinds of work are performed with the help of draught animals or done manually due to insufficient equipment or because of the impossibility of using machinery for some reason. Manual labour demands as a rule considerable physical effort. Power requirements during ploughing, horse-drawn sowing and manual mowing can amount to 5,000 to 6,000 cal/day and more.

Injuries are common during manual work, especially among inexperienced workers, and cases of plant burns, insect and reptile stings and dermatitis from the sap of some plants are frequent.

Prevention

One of the main trends in tractor construction is the improvement of working conditions of tractor operators. Side by side with perfection of the design of protective cabs is the search for ways of coordinating technical parameters of various tractor units with the functional abilities of operators. The aim of this research consists of ensuring the effectiveness of control and driving functions as well as necessary ergonomic parameters of the workplace environment.

Effectiveness of control and driving of tractor assemblies is ensured by good visibility of the working zone, by optimizing assemblies and control panel design and by proper ergonomic design of tractor seats.

Common ways of increasing visibility are increasing the viewing area of the cab using panoramic glass, improved layout of auxiliary equipment (e.g., fuel tank), rationalization of seat location, use of rear view mirrors and so on.

Optimization of construction control elements is connected with the construction of the control mechanism’s drive. Along with hydraulic and electric drives, a new improvement is suspended control pedals. This allows improved access and increased driving comfort. Functional coding (by means of form, colour and/or symbolic signs) plays an important part in recognition of the control elements.

Rational layout of instrumentation (which comprises 15 to 20 units in modern tractors) requires taking into account further increases in indicators due to remote control of technological process conditions, automation of the driving and operating of the technological equipment.

The operator’s seat is designed to guarantee a comfortable position and effective driving of the machine and tractor assembly. Design of modern tractor seats takes into account anthropometric data of the human body. Seats have adjustable back and arms and can be adjusted according to the operator’s size, in both horizontal and vertical dimensions (figure 2).

Figure 2. Angle parameters of optimal work posture of a tractor driver

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Precautions against harmful working conditions for tractor drivers include means of protection against noise and vibration, microclimate normalization and airtight sealing of cabs.

Besides special engineering of the engine to reduce noise at its source, considerable effect is achieved by mounting the engine on vibration isolators, isolating the cab from the tractor body with the help of shock absorbers and a number of measures designed for absorption of noise in the cab. Flaky, sound-absorbing lagging with a decorative surface is applied for this purpose to cab wall panels, and rugs made of rubber and porolon are laid on the cab floor. Hard perforated panelling with an air gap of 30 to 50 mm is applied to the ceiling. These measures have reduced noise levels in cabs to 80–83 dBA.

The main means of damping low-frequency vibration in the cab is use of an effective seat suspension. Nevertheless, the effect of whole-body vibration damping achieved this way does not exceed 20 to 30%.

Agricultural ground levelling gives considerable opportunities for decreasing vibration.

Improvement of the microclimate conditions in tractor cabs is reached with the help of both standard equipment (e.g., fans with filter elements, thermo-insulating tinted glass, sun-proof cap peaks, adjustable louvers) and special devices (e.g., air conditioners). Modern tractor heating systems are designed as an autonomous assembly attached to the engine’s cooling system and using warmed water to heat the air. Combined air conditioners and air heaters are also available.

Complex solutions of the problem of noise, vibration and heat isolation and sealing of cabs can be reached with the help of sealed cab capsules designed with suspended control pedals and wire rope systems of drives.

Ease of access to tractor engines and assemblies for their maintenance and repairs, as well as obtaining timely information about technical condition of certain units of the assembly, are important indices of the level of tractor operator working conditions. Eliminating the cab bonnet, forward inclination of the cab, detachable panels of the engine’s bonnet and so on are available in certain types of tractors.

In the future, tractor cabs are likely to be equipped with automatic control units, with television screens for observation of implements that are out of the operator’s field of vision and with units for conditioning of microclimate. Cabs will be mounted on outside rotary rods so they can be moved to a required position.

Rational organization of work and rest is of great importance for the prevention of fatigue and diseases of agricultural workers. In the hot season, daily routine ought to provide for working mainly in the morning and evening hours, reserving the hottest time for rest. During exhausting work (moving, hoeing), short regular breaks are necessary. Special attention has to be devoted to the rational, balanced nourishment of workers with due regard for the energy requirements of the tasks. Drinking regularly during the heat is of great importance. As a rule, workers drink traditional beverages (tea, coffee, fruit juices, infusions, broths and so on) in addition to water. Availability of sufficient amounts of wholesome liquids of high quality is very important.

Availability of comfortable overalls and personal protection equipment (PPE) (respirators, hearing protectors), especially during contact with dust and chemicals, is very important as well.

Medical control of the agricultural workers’ health has to be oriented to prevention of common occupational diseases, such as infectious diseases, chemical exposures, injuries, ergonomic problems and so forth. Teaching safe working methods, information about matters of hygiene and sanitation are of great importance.

 

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Monday, 28 March 2011 20:18

Power Generation and Water Treatment

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In addition to liquor recovery, pulp mills recover a significant portion of energy from burning waste materials and by-products of the process in power boilers. Materials such as bark, wood waste and dried sludge collected from effluent treatment systems may be burned to provide steam to power electrical generators.

Pulp and paper mills consume vast amounts of fresh water. A 1,000 tonne per day bleached kraft pulp mill may use more than 150 million litres of water a day; a paper mill even more. In order to prevent adverse effects on mill equipment and to maintain product quality, the incoming water must be treated to remove contaminants, bacteria and minerals. Several treatments are applied depending on the quality of the incoming water. Sedimentation beds, filters, flocculants, chlorine and ion exchange resins are all used to treat water before it is used in the process. Water that is used in the power and recovery boilers is further treated with oxygen scavengers and corrosion inhibitors such as hydrazine and morpholine to avoid deposits forming in the boiler tubes, to reduce metal corrosion, and to prevent carry-over of water to the steam turbine.

 

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Thursday, 10 March 2011 14:48

Harvesting Operations

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The gathering in of agricultural crops upon maturity, or the practice of harvesting, signals the end of the production cycle prior to storage and processing. The size and quality of the crop removed from the field, orchard or vineyard represents the most significant measure of a farmer’s productivity and success. The value that has been placed on the outcome of the harvest is reflected in the terms used almost universally to measure and compare agricultural productivity, such as kilograms per hectare (kg/ha), bales per hectare, bushels per acre (bu/a) and tons per acre or hectare. From an agronomic perspective, it is actually the inputs that determine the yield; however, it is the harvest that becomes the primary determinant of whether or not there will be sufficient seed and resources to ensure the sustainability of the farm and those it supports. Because of the significance of harvest and all of its related activities, this part of the agricultural cycle has taken on an almost spiritual role in the lives of farmers throughout the world.

Few agricultural practices illustrate more clearly the scope and diversity of technology- and work-related hazards found in agricultural production than harvesting. Crop harvesting is carried out under a wide variety of conditions, over various types of terrain, utilizing machines from simple to complex that must handle a diversity of crops; it involves considerable physical effort from the farmer (Snyder and Bobick 1995). For these reasons, any attempt to briefly generalize the characteristics or nature of harvest practices and harvest-related hazards is extremely difficult. Small grains (rice, wheat, barley, oats and so on), for example, which dominate much of the planted cropland in the world, represent not only some of the most highly mechanized crops, but in large regions of Africa and Asia are harvested in a manner that would be familiar to farmers 2,500 years ago. The use of hand sickles to harvest a few stalks at a time, hard-packed clay threshing floors and simple threshing devices remain the primary tools of harvest for far too many producers.

The primary hazards associated with the more labour-intensive harvesting practices have changed little with time and are often overshadowed by the perceived increased risks associated with greater mechanization. Long hours of exposure to the elements, the physical demands resulting from lifting heavy loads, repetitive motion and awkward or stooped posture, along with natural hazards such as poisonous insects and snakes, have historically taken, and continue to take, a significant toll (see figure 1). Harvesting grain or sugar cane with a sickle or machete, picking fruit or vegetables by hand and manually removing peanuts from the vine are dirty, uncomfortable and exhausting tasks that in many communities frequently are completed by large numbers of children and women. One of the strongest motivating forces that has shaped modern harvesting practices has been the desire to remove the physical drudgery associated with manual harvesting.

Figure 1. Hand-harvesting millet

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Even if the resources were available to mechanize harvesting and reduce its risks (and for many small farmers in many areas of the world, they are not), investments to improve the safety and health aspects of harvesting would likely have smaller returns than would comparable investments to improve housing, water quality or health care. This is especially true if farmers have access to large numbers of unemployed or underemployed workers. High levels of unemployment and limited job opportunities, for example, place large numbers of younger workers at risk of injury during harvest because they are cheaper to use than machines. Even in many countries with highly mechanized agricultural practices, child labour laws frequently exempt children involved in agricultural activities. For example, special provisions of the US Department of Labor child labour laws continue to exempt children under 16 during harvest and allow them to operate agricultural equipment under certain conditions (DOL 1968).

Contrary to a general perception that greater mechanization in agriculture has increased the risks associated with agricultural production, with respect to harvesting, nothing could be further from the truth. Through the introduction of intensive mechanization in major grain- and forage-producing regions, the amount of time required to produce a bushel of grain, for example, has dropped from over an hour to under a minute (Griffin 1973). This accomplishment, though heavily dependent upon fossil fuels, has released tens of millions of people from the drudgery and unsafe working conditions associated with hand harvesting. Mechanization has resulted in not only tremendous increases in productivity and yields, but also the near elimination of the most historically significant harvest-related injuries, such as those involving livestock.

The intensive mechanization of the harvesting process, however, has introduced new hazards, which have required periods of adjustment and in some cases the replacement of machines with improved practices and designs that were either more productive or less hazardous. An example of this technological evolution was experienced with the transition that took place in corn harvesting in North America between the 1930s and 1970s. Up through the 1930s, the corn crop was almost entirely harvested by hand and transported to on-farm storage sites by horse-drawn wagons. The primary cause of harvest-related injuries was related to working with horses (NSC 1942). With the introduction and widespread use of the mechanical, tractor-drawn corn picker in the 1940s, horse- and livestock-related deaths and injuries rapidly declined during the harvest period, and there was a corresponding growth in the number of corn picker-related injuries. This was not because corn pickers were inherently more dangerous, but because the injuries reflected a rapid transition to a new practice that had not been fully refined and that farmers were unfamiliar with. As farmers adjusted to the technology and manufacturers improved the performance of the corn picker, and as more uniform varieties of corn were planted that were better suited to machine harvesting, the number of deaths and injuries quickly declined. In other words, the introduction of the corn picker ultimately resulted in a decline in harvest- related injuries due to exposure to traditional hazards.

With the introduction in the 1960s of the self-propelled combine, which could harvest higher-yielding corn varieties at rates ten or more times faster than the corn picker, corn picker injuries almost disappeared. But, once again, as with the corn picker, the combine introduced a new set of hazards that required a period of adjustment. For example, the ability to gather, cut, separate and clean the grain in the field using one machine changed the handling of grain from a lumpy flow process in the form of ear corn to shelled corn, which was almost fluid-like. Consequently, in the 1970s, there was a dramatic increase in the number of auger-related injuries, and of engulfments and suffocations in flowing grain that took place in storage structures and grain transport vehicles (Kelley 1996). In addition, there were new categories of injuries being reported that were related to the sheer size and weight of the combine, such as falls from the operator platform and ladders, which can place the operator as much as 4 m off the ground, and operators being crushed beneath the multi-row gathering unit.

The mechanization of the corn harvest directly contributed to one of the most dramatic shifts in rural population ever experienced in North America. The farm population, in less than 75 years after the introduction of hybrid varieties of corn and the mechanical corn picker, went from over 50% to less than 5% of the total population. Through this period of increased productivity and greatly reduced labour demands, the overall exposure to agricultural workplace hazards was substantially reduced, contributing to a drop in reported farm-related deaths from over 14,000 in 1942 to fewer than 900 in 1995 (NSC 1995).

Injuries associated with modern harvesting operations typically relate to tractors, machinery, grain-handling equipment and grain-storage structures. Since the 1950s, tractors have contributed to approximately one-half of all farm-related fatalities, with overturns being the single most important contributing factor. The utilization of rollover protective structures (ROPS) has proven to be the single most important intervention strategy in reducing the number of tractor-related fatalities (Deere & Co. 1994). Other design features that improved the safety and health of tractor operators included wider wheel bases and designs that lowered the centre of gravity to improve stability, all-weather operator enclosures to reduce exposure to the elements and dust, ergonomically designed seating and controls and reduced noise levels.

The problem of tractor-related injuries, however, remains significant and is a growing concern in areas that are being rapidly mechanized, such as China and India. In many areas of the world it is more likely to see the tractor being used as a vehicle of highway transport or a stationary power source than being used in the field to produce crops, as it was designed to do. In these areas, tractors are typically introduced with minimal operator training and are used widely as a means of transporting multiple passengers, another use for which the tractor was not designed. The result has been that runovers of extra riders who have fallen from the tractors during operation has become the second leading cause of tractor-related fatalities. If the trend towards greater utilization of ROPS continues, runovers may eventually become the leading cause of tractor-related fatalities worldwide.

Though used fewer hours during the year than tractors, harvesting equipment such as combines are involved in about twice as many injuries per 1,000 machines (Etherton et al. 1991). These injuries often take place during servicing, repairing or adjusting the machine when the power to machine components is still engaged (NSC 1986). Recent design changes have been made to incorporate more passive and active operator warnings and interlocks, such as safety switches in the operator seat to prevent machine operation when no one is in the seat, and to reduce the number of maintenance points to reduce operator exposure to operating machinery. Many of these design concepts, however, remain voluntary, are frequently by-passed by the operator and are not universally found on all harvesting machines.

Hay and forage harvesting equipment exposes workers to hazards similar to those found on combines. This equipment contains components that cut, crush, grind, chop and blow crop material at high speed, leaving little room for human error. As with grain harvesting, hay and forage harvesting must take place in a timely fashion in order to prevent damage to the crop from the elements. This added stress to complete tasks rapidly, in conjunction with machine hazards, frequently leads to injuries (Murphy and Williams 1983).

Traditionally, the hay baler has been identified as a frequent source of serious injuries. These machines are used under some of the most harsh conditions found in any type of harvesting. High temperature, rough terrain, dusty conditions and the need for frequent adjustments contribute to a high rate of injury. The conversion to large packages or bales of hay and mechanical handling systems has improved safety with a few exceptions, as was the case with the introduction of the early designs of the round baler. The aggressive compression rolls on the front of these machines resulted in a large number of hand and arm amputations. This design was later replaced with a less aggressive gathering unit, which nearly eliminated the problem.

Fire is a potential problem for many types of harvesting operations. Crops that are required to be dried to less than 15% moisture content for proper storage make excellent fuel if ignited. Combines and cotton harvesters are especially vulnerable to fires during field operation. Design features such as the use of diesel engines and protected electrical systems, proper equipment maintenance and operator access to fire extinguishers have been shown to reduce the risk of fire-related damage or injury (Shutske et al. 1991).

Noise and dust are two other hazards that are typically intrinsic to harvesting operations. Both pose serious long-term health risks to the operator of harvesting equipment. The inclusion of environmentally controlled operator enclosures in the design of modern harvesting equipment has done much to reduce operator exposure to excessive noise pressures and dust levels. However, most farmers have yet to benefit from this safety feature. The use of PPE such as ear plugs and disposable dust masks provides an alternative, but less effective, means of protection from these hazards.

As harvesting operations around the world become increasingly mechanized, there will be a continuing shift from environmental-, animal- and hand tool-related injuries to those caused by machines. Drawing upon the experiences of farmers and manufacturers of harvesting equipment who have completed this transition should prove useful in reducing the adjustment period and preventing injuries caused by lack of familiarity and poor design. The experience of farmers with even the most highly mechanized harvesting operations, however, suggests that the injury problem will not be totally eliminated. Contributions of operator error and machine design will continue to play a significant role in injury causation. But there is no question that in addition to greater productivity, the process of mechanization has significantly reduced the risks associated with harvesting.

 

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Monday, 28 March 2011 20:19

Chemical and By-product Production

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Because many bleaching chemicals are reactive and hazardous to transport, they are produced on-site or nearby. Chlorine dioxide (ClO2), sodium hypochlorite (NaOCl) and peracids are always produced on-site, while chlorine (Cl2) and sodium hydroxide or caustic (NaOH) are usually produced off-site. Tall oil, a product derived from the resin and fatty acids that are extracted during kraft cooking, may be refined on- or off-site. Turpentine, a lighter fraction kraft by-product, is often collected and concentrated on-site, and refined elsewhere.

Chlorine Dioxide

Chlorine dioxide (ClO2) is a highly reactive greenish-yellow gas. It is toxic and corrosive, explodes at high concentrations (10%) and is quickly reduced to Cl2 and O2 in the presence of ultraviolet light. It must be prepared as a dilute gas and stored as a dilute liquid, making bulk transport impossible.

ClO2 is generated by reducing sodium chlorate (Na2ClO3) with either SO2, methanol, salt or hydrochloric acid. The gas leaving the reactor is condensed and stored as a 10% liquid solution. Modern ClO2 generators operate at 95% efficiency or greater, and the small amount of Cl2 that is produced will be collected or scrubbed out of the vent gas. Side reactions may occur depending on the purity of the feed chemicals, the temperature and other process variables. By-products are returned to the process and spent chemicals are neutralized and sewered.

Sodium Hypochlorite

Sodium hypochlorite (NaOCl) is produced by combining Cl2 with a dilute solution of NaOH. It is a simple, automated process that requires almost no intervention. The process is controlled by maintaining the caustic concentration such that the residual Cl2 in the process vessel is minimized.

Chlorine and Caustic

Chlorine (Cl2), used as a bleaching agent since the early 1800s, is a highly reactive, toxic, green-coloured gas which becomes corrosive when moisture is present. Chlorine is usually manufactured by the electrolysis of brine (NaCl) into Cl2 and NaOH at regional installations, and transported to the customer as a pure liquid. Three methods are used to produce Cl2 on an industrial scale: the mercury cell, the diaphragm cell, and the most recent development, the membrane cell. Cl2 is always produced at the anode. It is then cooled, purified, dried, liquefied and transported to the mill. At large or remote pulp mills, local facilities may be constructed, and the Cl2 can be transported as a gas.

The quality of NaOH depends on which of the three processes is used. In the older mercury cell method, the sodium and mercury combine to form an amalgam that is decomposed with water. The resulting NaOH is nearly pure. One of the shortcomings of this process is that mercury contaminates the workplace and has resulted in serious environmental problems. The NaOH produced from the diaphragm cell is removed with the spent brine and concentrated to allow the salt to crystallize and separate. Asbestos is used as the diaphragm. The purest NaOH is produced in membrane cells. A semi-permeable resin-based membrane allows sodium ions to pass through without the brine or chlorine ions, and combine with water added to the cathode chamber to form pure NaOH. Hydrogen gas is a by-product of each process. It is usually treated and used either in other processes or as fuel.

Tall Oil Production

Kraft pulping of highly-resinous species such as pine produces sodium soaps of resin and fatty acids. The soap is collected from black liquor storage tanks and from soap skimming tanks that are located in the evaporator train of the chemical recovery process. Refined soap or tall oil can be used as a fuel additive, dust control agent, road stabilizer, pavement binder and roofing flux.

At the processing plant, soap is stored in primary tanks to allow the black liquor to settle to the bottom. The soap rises and overflows into a second storage tank. Sulphuric acid and the decanted soap are fed into a reactor, heated to 100°C, agitated and then allowed to settle. After settling overnight, the crude tall oil is decanted into a storage vessel and allowed to sit for another day. The top fraction is considered dry crude tall oil and is pumped to storage, ready for shipment. The cooked lignin in the bottom fraction will become part of the subsequent batch. The spent sulphuric acid is pumped to a storage tank, and any entrained lignin is allowed to settle to the bottom. The lignin left in the reactor is concentrated for several cooks, dissolved in 20% caustic and returned to the primary soap tank. Periodically, the collected black liquor and the residual lignin from all sources are concentrated and burned as fuel.

Turpentine Recovery

Gases from the digesters and condensate from black liquor evaporators may be collected for recovery of turpentine. The gases are condensed, combined, then stripped of turpentine, which is recondensed, collected and sent to a decanter. The top fraction of the decanter is drawn off and sent to storage, while the bottom fraction is recycled to the stripper. Raw turpentine is stored separately from the rest of the collection system because it is noxious and flammable, and is usually processed off-site. All the non-condensable gases are collected and incinerated either in the power boilers, the lime kiln or a dedicated furnace. The turpentine can be processed for use in camphor, synthetic resins, solvents, flotation agents and insecticides.

 

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Thursday, 10 March 2011 14:49

Storing and Transportation Operations

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Storing

The growing and gathering of crops and production of livestock has long been recognized as one of the world’s oldest and most important occupations. Farming and ranching today is as diverse as the many crops, fibres and livestock which are produced. At one extreme, the farming unit may consist of a single family that cultivates the soil and plants and harvests the crop, all by hand over a limited area. The opposite extreme includes large corporate farms spanning vast areas that are highly mechanized, using sophisticated machinery, equipment and facilities. The same is true for the storage of food and fibre. Storage of agricultural products may be as rudimentary as simple huts and hand-dug pits, and as complex as towering silos, bunkers, bins and refrigerated units.

Hazards and their prevention

Agricultural products such as grains, hays, fruit, nuts, vegetables and plant fibre are often stored for later human and livestock consumption or sale to the general populace or to manufacturers. The storage of agricultural products prior to shipment to market may occur in a variety of structures—pits, bunkers, bins, silos, refrigerated units, carts, wagons, barns and railroad cars, to mention a few. Despite the diversity of products being stored and of storage facilities, there are hazards which are common to the storage process:

Falls and falling objects

Falls may occur from heights or at the same level. In the case of bins, silos, barns and other storage structures, falls from heights most often occur from and in storage structures. Most often the cause is unguarded roofs, floor openings, stairways, lofts and shafts, and climbing ladders or standing on raised work areas such as an unprotected platform. Falls from height may also result from climbing on or off the transportation unit (e.g., wagons, carts and tractors). Falls from the same level occur from slippery surfaces, tripping over objects or being pushed by a moving object. Protection against falls includes such measures as:

  • provision of safety belts, harnesses, lifelines and safety boots
  • installation of guard rails, toeboards, cat-ladders or crawling boards on sloped roofs
  • guarded floor openings, lofts and shafts
  • use of the standard rise and run of stairways, provision of handrails on both sides, and application non-skid strips where necessary
  • maintaining floors in good condition, free from uneven surfaces, holes and accumulations of waste or slippery substances
  • provision of handholds on permanent ladders, guard platforms and landings
  • maintaining extension or step ladders in good condition and training employees on their use.

 

Agricultural products may be stored loose in a facility or bundled, bagged, crated or bailed. Loose storage is often associated with grains such as wheat, corn or soybeans. Bundled, bagged, crated or bailed products include hay, straw, vegetables, grains and feeds. Falls of materials occur in all types of storage. Collapse of unsecured stacked foodstuffs, overhead materials and piles of goods are often causes of injury. Employees should be trained in the correct stacking of goods to prevent their collapse. Employers and managers must monitor the workplace for compliance.

Confined spaces

Agricultural products may be stored in two types of facilities—those that contain enough oxygen to sustain life, such as barns, open carts and wagons, and those that do not, such as some silos, tanks and refrigeration units. The latter are confined spaces, and should be treated with appropriate precautions. The oxygen level should be monitored prior to entry and a supplied air or self-contained breathing unit used if necessary; someone else should be on hand. Suffocation may also occur in either type of facility if the goods which it contains have the characteristics of a fluid. This is commonly associated with grains and similar foodstuffs. The worker dies as a result of drowning. In grain bins it is a common practice for an agricultural worker to enter the bin due to difficulties in loading or unloading, often caused by a condition of the grain resulting in bridging. Workers attempting to alleviate the situation by unbridging the grain may voluntarily walk on the bridged grain. They may fall in and be covered with the grain or be sucked under if the loading or unloading equipment is operational. Bridging also may occur to the sides of such structures, in which case a worker may enter to knock down the material sticking to the sides and become engulfed when the material fails. A lockout/tagout system and fall protection such as a safety belt and rope are essential if workers are to enter this type of structure. Children’s safety is of special concern. Often inquisitive, playful and wanting to do adult chores, they are attracted to such structures, and the results are all-too-often fatal.

Fruit and vegetables are often kept in cold storage prior to shipping to market. As indicated in the above paragraph, depending on the type of unit, cold storage may be considered a confined space and should be monitored for oxygen content. Other hazards include frostbite and cold-induced injury or death from body temperature loss following prolonged exposure to cold. Personal protective clothing should be worn appropriate to the temperature within the cold-storage unit.

Gases and poisons

Depending on the moisture content of the product when it is placed in storage and atmospheric and other conditions, feeds, grains and fibres may produce dangerous gases. Such gases include carbon monoxide (CO), carbon dioxide (CO2) and oxides of nitrogen (NOx), some of which may cause death in a matter of minutes. This is also especially important if the goods are stored in a facility in which nonlethal gases may be allowed to accumulate to dangerous levels, displacing oxygen. If the potential for gas production exists, then monitoring for gases should be done. In addition, foods and feeds may have been sprayed or treated with a pesticide during the growing period to kill weeds, insects or disease, or during the storage process to reduce spoilage or mould, spore or insect damage. This may add to the hazards of gas production, inhalation of dusts and handling of the product. Special care should be taken by workers to wear PPE depending on the nature and longevity of the treatment, the product used and the label directions.

Machine hazards

Storage facilities may contain a variety of machinery for conveying the product. These range from belt and roller conveyors to blowers, augers, slides and other such product-handling devices, each with its own power source. Hazards and suitable precautions include:

  • Nip points formed by belts, pulleys and gears. Agricultural workers should be protected from nip and shear points by an appropriate guarding around the point of potential contact.
  • Protruding belt fasteners, setscrews, keys, bolts and grooves. Protruding setscrews, keys or bolts on revolving shafts should be countersunk, encased or shrouded. Belt fasteners should be inspected and repaired.
  • Shear points caused by flywheel arms, augers and their housing, pulley spokes, crank and lever mechanisms. These should be guarded or enclosed.
  • Contact with moving transmission or electrical elements. These should be guarded or enclosed.
  • Inadvertent starting of machinery or equipment. A system for locking out or tagging out equipment prior to maintenance or repair should be implemented and enforced.
  • Loose clothing or hair getting wound on or caught by shafts. Clothing that is loose, frayed or that has hanging threads should never be worn. Other personal protective apparel and shoes appropriate to the job task should be worn.
  • Excessive noise. Noise exposure should be monitored and administrative, engineering and/or personal protective controls should be taken if necessary.

 

Employees should be trained and aware of the hazards, basic safety rules and safe working methods.

Health outcomes

Agricultural workers who are involved in the handling of agricultural products for storage are at risk for respiratory disorders. Exposures to a variety of dusts, gases, chemicals, silica, fungal spores and endotoxins can result in damage to the lungs. Recent studies link lung disorders caused by these substances to workers who handle grain, cotton, flax, hemp, hay and tobacco. Therefore the populations at risk are worldwide. Agricultural lung disorders have many common names, some of which include: occupational asthma, farmer’s lung, green tobacco sickness, brown lung, organic dust toxic syndrome, silo filler’s or unloader’s disease, bronchitis and airway obstruction. Symptoms may first manifest themselves as being characteristic of influenza (chills, fever, coughing, headaches, myalgias and breathing difficulty). This is especially true for organic dusts. Prevention of lung dysfunction should include an assessment of the worker’s environment, health promotion programmes targeted at primary prevention and the use of personal protective respirators and other protective devices based on the environmental assessment.

Transportation Operations

Although it may seem simple, the transportation of goods to market is often as complex and hazardous as growing and storing the crop. The transportation of products to market is as diversified as the types of farming operations. Transportation may range from goods being carried by humans and livestock, to being transported by simple mechanical devices such as bicycles and animal-drawn carts, being hauled by complex mechanical equipment such as large carts and wagons pulled by tractors, to the use of commercial transportation systems, which include large trucks, buses, trains and airplanes. As the world’s population increases and urban areas grow, road travel of agricultural equipment and implements of husbandry has increased. In the US, according to the National Safety Council (NSC), 8,000 farm tractors and other agricultural vehicles were involved in highway accidents in 1992 (NSC 1993). Many farming operations are consolidating and expanding by acquiring or renting a number of smaller farms which are typically scattered and not adjoining. A 1991 study in Ohio showed that 79% of the farms surveyed operated in multiple locations (Bean and Lawrence 1992).

Hazards and their prevention

Although each of the modes of transportation mentioned above will have its own unique hazards, it is the intermix of civilian traffic with agricultural transport machinery and equipment that is of major concern. The increase in road travel of agricultural equipment has resulted in a greater number of collisions between motor vehicles and slower moving agricultural equipment. Farm equipment and implements of husbandry may be wider than the width of the road. Due to pressure of planting at the right time to assure a crop or harvesting and getting the crop to a market or storage location as quickly as possible, agricultural machinery must often travel on the roadways during periods of darkness, early morning or evening.

An in-depth study of all 50 states’ codes in the United States revealed that the lighting and marking requirements vary greatly from state to state. This diversity in requirements does not communicate a consistent message to motor vehicle drivers (Eicher 1993). Faster speeds of other vehicles combined with inadequate lighting or marking of agricultural equipment is often a deadly combination. A recent study in the United States found that the common accident types are rear end, sideswipe-meeting, sideswipe-passing, angle, head-on, backing and other. In 20% of the 803 two-vehicle crashes studied, the farm vehicle was struck from an angle. In 28% of the crashes, the farm vehicle was sideswiped (15% meeting and 13% passing). Twenty-two per cent of the accidents consisted of rear-end (15%), head-on (4%) and backing (3%) collisions. The remaining 25% were crashes which were caused by something other than a moving vehicle (i.e., a parked vehicle, pedestrian, animal and so on) (Glascock et al. 1993).

Livestock are used in many parts of the world as the “horsepower” to transport agricultural products. Although beasts of burden are generally reliable, most are colourblind, have territorial and maternal instincts, react independently and unexpectedly, and are of great strength. Such animals have caused vehicle crashes. Falls from agricultural machinery and implements of husbandry are common.

The following general safety principles apply to transportation operations:

  • Local traffic rules, regulations or laws should be learned and obeyed.
  • No riders or passengers other than those that are necessary to accomplish the transport and unloading duties should be permitted.
  • Vehicles should stay as close to the shoulder of the road as road conditions will allow.
  • Passing other vehicles (moving or parked) and pedestrians must be done with caution.
  • Broken-down vehicles should be moved off the road if possible.
  • All marking and lighting on machinery and equipment should be maintained and clean.
  • Driving should never be done under the influence of alcohol or drugs.

 

Laws and regulations may dictate the state of acceptable lighting and marking. However, many such regulations only describe the minimal acceptable standards. Unless such regulations specifically prohibit retrofitting and adding additional lighting and marking, farmers should consider adding such devices. It is important that such lighting and marking devices be installed not only on self-propelled implements but also on pieces of equipment that they may be pulling or trailing.

Lights are especially critical for dusk, dawn and night-time movement of agricultural equipment. If the agricultural vehicle has a power source, consideration should be given to having, at a minimum: two headlights, two tail-lights, two turn signals and two brake lights.

Tail-lights, turn signals and brake lights may be incorporated into single units or can be attached as separate entities. Standards for such devices may be found through standard-setting organizations such as the American Society of Agricultural Engineers (ASAE), the American National Standards Institute (ANSI), the European Committee for Standardization (CEN) and the International Organization for Standardization (ISO).

If the agricultural vehicle does not have a power source, battery-powered lights, although not as effective, may be used. Many such lights are commercially available in a variety of types (flood, blinking, rotating and strobe) and sizes. If it is impossible to obtain these devices, then reflectors, flags and other alternative materials discussed below may be used.

Many new retroreflective fluorescent materials are available today to aid in marking agricultural vehicles for enhanced visibility. They are manufactured in patches or strips in a variety of colours. Local regulations should be consulted for acceptable colours or colour combinations.

Fluorescent materials provide excellent daytime visibility by relying on solar radiation for their light-emitting properties. A complex photochemical reaction takes place when the fluorescent pigments absorb non-visible solar radiation and re-emit the energy as a longer wavelength of light. In a sense, fluorescent materials appear to “glow” in the daytime and appear brighter than the conventional colours in the same light conditions. The primary disadvantage of fluorescent materials is their deterioration with prolonged exposure to solar radiation.

Reflection is an element of sight. Wavelengths of light strike an object and are either absorbed or bounced back in all directions (diffused reflection) or at an angle exactly opposite to the angle at which the light struck the object (specular reflection). Retroreflectivity is very similar to specular reflection; however, the light is reflected directly back toward the light source. There are three primary forms of retroreflective materials, each having a different degree of retroreflectivity based on how they were manufactured. They are presented here in increasing order of retroreflectivity: enclosed lens (often called engineering grade or Type ID), encapsulated lens (high intensity) and cube corner (diamond grade, prismatic, DOT C2 or Type IIIB). These retroreflective materials are excellent for night-time visual identification. These materials are also of great assistance in defining the extremities of agricultural implements. In this application, strips of retroreflective and fluorescent material across the width of the machinery, front and back, best communicate to drivers of other, nonagricultural vehicles the actual width of the equipment.

The distinctive red triangle with a yellow-orange centre is used in the United States, Canada and many other parts of the world to designate a class of vehicles as “slow moving”. This means the vehicle travels less than 40 km per hour on the roadway. Typically, other vehicles travel much faster, and the difference in speed may result in a misjudgement on the part of the faster vehicle driver, affecting the driver’s ability to stop in time to avoid an accident. This emblem or an acceptable substitute should always be used.

Health outcomes

Agricultural workers who are involved in the transportation of agricultural products may be at risk for respiratory disorders. Exposures to a variety of dusts, chemicals, silica, fungal spores and endotoxins may result in damage to the lungs. This is somewhat dependent on whether the transport vehicle has an enclosed cab and whether the operator engages in the loading and unloading process. If the transport vehicle has been used in the process of pesticide application, pesticides could be present and trapped inside the cab unless it has an air filtration system. Nevertheless, symptoms may first manifest themselves as being characteristic of influenza. This is especially true for organic dusts. Prevention of lung dysfunction should include an assessment of the worker’s environment, health promotion programmes targeted at primary prevention and the use of personal protective masks, respirators and other protective devices.

 

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Monday, 28 March 2011 20:20

Occupational Hazards and Controls

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Table 1 provides an overview of the types of exposures which may be expected in each area of pulp and paper operations. Although exposures may be listed as specific to certain production processes, exposures to employees from other areas may also occur depending on weather conditions, proximity to sources of exposure, and whether they work in more than one process area (e.g., quality control, general labour pool and maintenance personnel).

Table 1. Potential health and safety hazards in pulp and paper production, by process area

Process area

Safety hazards

Physical hazards

Chemical hazards

Biological hazards

Wood preparation

       

Log pond

Drowning; mobile equipment;
slipping, falling

Noise; vibration; cold; heat

Engine exhaust

 

Wood room

Nip points; slipping, falling

Noise; vibration

Terpenes and other wood extracts; wood dust

Bacteria; fungi

Chip screening

Nip points; slipping, falling

Noise; vibration

Terpenes and other wood extracts; wood dust

Bacteria; fungi

Chip yard

Nip points; mobile equipment

Noise; vibration; cold; heat

Engine exhaust; terpenes and other wood extracts; wood dust

Bacteria; fungi

Pulping

       

Stone groundwood
pulping

Slipping, falling

Noise; electric and magnetic fields; high humidity

   

RMP, CMP, CTMP

Slipping, falling

Noise; electric and magnetic fields; high humidity

Cooking chemicals and by-products; terpenes and other wood extracts; wood dust

 

Sulphate pulping

Slipping, falling

Noise; high humidity; heat

Acids and alkalis; cooking chemicals and by-products; reduced sulphur gases; terpenes
and other wood extracts; wood dust

 

Sulphate recovery

Explosions; nip points; slipping,
falling

Noise; heat; steam

Acids and alkalis; asbestos; ash; cooking chemicals and by-products; fuels; reduced
sulphur gases; sulphur dioxide

 

Sulphite pulping

Slipping, falling

Noise; high humidity; heat

Acids and alkalis; cooking chemicals and by-products; sulphur dioxide; terpenes and other wood extracts; wood dust

 

Sulphite recovery

Explosions; nip points; slipping,
falling

Noise; heat; steam

Acids and alkalis; asbestos; ash; cooking chemicals and by-products; fuels; sulphur dioxide

 

Repulping/de-inking

Slipping, falling

 

Acids and alkalis; bleaching chemicals and by- products; dyes and inks; pulp/paper dust; slimicides; solvents

Bacteria

Bleaching

Slipping, falling

Noise; high humidity; heat

Bleaching chemicals and by-products; slimicides; terpenes and other wood extracts

 

Sheet forming and
converting

       

Pulp machine

Nip points; slipping, falling

Noise; vibration; high
humidity; heat; steam

Acids and alkalis; bleaching chemicals and by-products; flocculant; pulp/paper dust; slimicides; solvents

Bacteria

Paper machine

Nip points; slipping, falling

Noise; vibration; high
humidity; heat; steam

Acids and alkalis; bleaching chemicals and by-products; dyes and inks; flocculant; pulp/paper
dust; paper additives; slimicides; solvents

Bacteria

Finishing

Nip points; mobile equipment

Noise

Acids and alkalis; dyes and inks; flocculant;
pulp/paper dust; paper additives; slimicides; solvents

 

Warehouse

Mobile equipment

 

Fuels; engine exhaust; pulp/paper dust

 

Other operations

       

Power generation

Nip points; slipping, falling

Noise; vibration; electric and
magnetic fields; heat; steam

Asbestos; ash; fuels; terpenes and other wood extracts; wood dust

Bacteria; fungi

Water treatment

Drowning

 

Bleaching chemicals and by-products

Bacteria

Effluent treatment

Drowning

 

Bleaching chemicals and by-products; flocculant; reduced sulphur gases

Bacteria

Chlorine dioxide
generation

Explosions; slipping, falling

 

Bleaching chemicals and by-products

Bacteria

Turpentine recovery

Slipping, falling

 

Cooking chemicals and by-products; reduced sulphur gases; terpenes and other wood extracts

 

Tall oil production

   

Acids and alkalis; cooking chemicals and by-products; reduced sulphur gases; terpenes and other wood extracts

 

RMP = refining mechanical pulping; CMP = chemi-mechanical pulping; CTMP = chemi-thermomechanical pulping.

 

Exposure to the potential hazards listed in table 1 is likely to depend on the extent of automation of the plant. Historically, industrial pulp and paper production was a semi-automatic process which required a great deal of manual intervention. In such facilities, operators would sit at open panels adjacent to the processes to view the effects of their actions. The valves at the top and bottom of a batch digester would be manually opened, and during the filling stages, gases in the digester would be displaced by the incoming chips (figure 1). Chemical levels would be adjusted based on experience rather than sampling, and process adjustments would be dependent on the skill and knowledge of the operator, which at times led to upsets. For example, over-chlorination of pulp would expose workers downstream to increased levels of bleaching agents. In most modern mills, progress from manually controlled to electronically controlled pumps and valves allows for remote operation. The demand for process control within narrow tolerances has required computers and sophisticated engineering strategies. Separate control rooms are used to isolate the electronic equipment from the pulp and paper production environment. Consequently, operators usually work in air-conditioned control rooms which offer refuge from the noise, vibration, temperature, humidity and chemical exposures inherent to mill operations. Other controls which have improved the working environment are described below.

Figure 1. Worker opening cap on manually controlled batch digester.

PPI100F1

MacMillan Bloedel archives

Safety hazards including nip points, wet walking surfaces, moving equipment and heights are common throughout pulp and paper operations. Guards around moving conveyors and machinery parts, quick clean-up of spills, walking surfaces which allow drainage, and guard-rails on walkways adjacent to production lines or at height are all essential. Lock-out procedures must be followed for maintenance of chip conveyors, paper machine rolls and all other machinery with moving parts. Mobile equipment used in chip storage, dock and shipping areas, warehousing and other operations should have roll-over protection, good visibility and horns; traffic lanes for vehicles and pedestrians should be clearly marked and signed.

Noise and heat are also ubiquitous hazards. The major engineering control is operator enclosures, as described above, usually available in wood preparation, pulping, bleaching and sheet-forming areas. Air-conditioned enclosed cabs for mobile equipment used in chip pile and other yard operations are also available. Outside these enclosures, workers usually require hearing protection. Work in hot process or outdoor areas and in vessel maintenance operations requires workers to be trained to recognize symptoms of heat stress; in such areas, work scheduling should allow acclimatization and rest periods. Cold weather may create frostbite hazards in outdoor jobs, as well as foggy conditions near chip piles, which remain warm.

Wood, its extracts and associated micro-organisms are specific to wood preparation operations and the initial stages of pulping. Control of exposures will depend on the particular operation, and may include operator booths, enclosure and ventilation of saws and conveyors, as well as enclosed chip storage and low chip inventory. Use of compressed air to clear wood dust creates high exposures and should be avoided.

Chemical pulping operations present the opportunity for exposures to digestion chemicals as well as gaseous by-products of the cooking process, including reduced (kraft pulping) and oxidized (sulphite pulping) sulphur compounds and volatile organics. Gas formation may be influenced by a number of operating conditions: the wood species used; the quantity of wood pulped; the amount and concentration of white liquor applied; the amount of time required for pulping; and maximum temperature attained. In addition to automatic digester capping valves and operator control rooms, other controls for these areas include local exhaust ventilation at batch digesters and blow tanks, capable of venting at the rate the vessel’s gases are released; negative pressure in recovery boilers and sulphite-SO2 acid towers to prevent gas leaks; ventilated full or partial enclosures over post-digestion washers; continuous gas monitors with alarms where leaks may occur; and emergency response planning and training. Operators taking samples and conducting tests should be aware of the potential for acid and caustic exposure in process and waste streams, and the possibility of side reactions such as hydrogen sulphide gas (H2S) production if black liquor from kraft pulping comes into contact with acids (e.g., in sewers).

In chemical recovery areas, acidic and alkaline process chemicals and their by-products may be present at temperatures in excess of 800°C. Job responsibilities may require workers to come into direct contact with these chemicals, making heavy duty clothing a necessity. For example, workers rake the spattering molten smelt that collects at the base of the boilers, thereby risking chemical and thermal burns. Workers may be exposed to dust when sodium sulphate is added to concentrated black liquor, and any leak or opening will release noxious (and potentially fatal) reduced sulphur gases. The potential for a smelt water explosion always exists around the recovery boiler. Water leaks in the tube walls of the boiler have resulted in several fatal explosions. Recovery boilers should be shut down at any indication of a leak, and special procedures should be implemented for transferring the smelt. Loading of lime and other caustic materials should be done with enclosed and ventilated conveyors, elevators and storage bins.

In bleach plants, field operators may be exposed to the bleaching agents as well as chlorinated organics and other by-products. Process variables such as bleaching chemical strength, lignin content, temperature and pulp consistency are constantly monitored, with operators collecting samples and performing laboratory tests. Because of the hazards of many of the bleaching agents used, continuous alarm monitors should be in place, escape respirators should be issued to all employees, and operators should be trained in emergency response procedures. Canopy enclosures with dedicated exhaust ventilation are standard engineering controls found at the top of each bleaching tower and washing stage.

Chemical exposures in the machine room of a pulp or paper mill include chemical carry-over from the bleach plant, the papermaking additives and the chemical mixture in the waste water. Dusts (cellulose, fillers, coatings) and exhaust fumes from mobile equipment are present in the dry-end and the finishing operations. Cleaning between product runs may be done with solvents, acids and alkalis. Controls in this area may include complete enclosure over the sheet drier; ventilated enclosure of the areas where additives are unloaded, weighed and mixed; use of additives in liquid rather than powder form; use of water-based rather than solvent-based inks and dyes; and eliminating the use of compressed air to clean up trimmed and waste paper.

Paper production in recycled paper plants is generally dustier than conventional paper production using newly produced pulp. Exposure to micro-organisms can occur from the beginning (paper collection and separation) to the end (paper production) of the production chain, but exposure to chemicals is less important than in conventional paper production.

Pulp and paper mills employ an extensive maintenance group to service their process equipment, including carpenters, electricians, instrument mechanics, insulators, machinists, masons, mechanics, millwrights, painters, pipefitters, refrigeration mechanics, tinsmiths and welders. Along with their trade-specific exposures (see the Metal processing and metal working and Occupations chapters), these tradespeople may be exposed to any of the process-related hazards. As mill operations have become more automated and enclosed, the maintenance, cleaning and quality assurance operations have become the most highly exposed. Plant shutdowns to clean vessels and machines are of special concern. Depending on mill organization, these operations may be carried out by in-house maintenance or production personnel, although subcontracting to non-mill personnel, who may have less occupational health and safety support services, is common.

In addition to process exposures, pulp and paper mill operations entail some noteworthy exposures for maintenance personnel. Because pulping, recovery and boiler operations involve high heat, asbestos was used extensively to insulate pipes and vessels. Stainless steel is often used in vessels and pipes throughout pulping, recovery and bleaching operations, and to some extent in papermaking. Welding this metal is known to generate chromium and nickel fumes. During maintenance shut-downs, chromium-based sprays may be applied to protect the floor and walls of recovery boilers from corrosion during start-up operations. Process quality measurements in the production line are often made using infrared and radio-isotope gauges. Although the gauges are usually well shielded, instrument mechanics who service them may be exposed to radiation.

Some special exposures may also occur among employees in other mill-support operations. Power boiler workers handle bark, waste wood and sludge from the effluent treatment system. In older mills, workers remove ash from the bottom of the boilers and then reseal the boilers by applying a mixture of asbestos and cement around the boiler grate. In modern power boilers, this process is automated. When material is fed into the boiler at too high a moisture level, workers may be exposed to blow-backs of incomplete combustion products. Workers responsible for water treatment may be exposed to chemicals such as chlorine, hydrazine and various resins. Because of the reactivity of ClO2, the ClO2 generator is usually located in a restricted area and the operator is stationed in a remote control room with excursions to collect samples and service the saltcake filter. Sodium chlorate (a strong oxidizer) used to generate ClO2 can become dangerously flammable if it is allowed to spill on any organic or combustible material and then dry. All spills should be wetted down before any maintenance work may proceed, and all equipment should be thoroughly cleaned afterward. Wet clothing should be kept wet and separate from street clothing, until washed.

 

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Contents

Preface
Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides