It is estimated that more than 80% of the world’s population live in the developing countries in Africa, the Middle East, Asia and South and Central America. The developing countries are often financially disadvantaged, and many have largely rural and agricultural economies. However, they are widely different in many ways, with diverse aspirations, political systems and varying stages of industrial growth. The status of health among people in the developing countries is generally lower than in the developed countries, as reflected by higher infant mortality rates and lower life expectancies.

Several factors contribute to the need for occupational safety and health surveillance in developing countries. First, many of these countries are rapidly industrializing. In terms of the size of industrial establishments, many of the new industries are small-scale industries. In such situations, safety and health facilities are often very limited or non-existent. In addition, developing countries are often the recipients of technology transfer from developed countries. Some of the more hazardous industries, which have difficulty in operating in countries with more stringent and better enforced occupational health legislation, may be “exported” to developing countries.

Second, with regard to the workforce, the education level of the workers in developing countries is often lower, and workers may be untrained in safe work practices. Child labour is often more prevalent in developing countries. These groups are relatively more vulnerable to health hazards at work. In addition to these considerations, there is generally a lower pre-existing level of health among workers in developing countries.

These factors would ensure that throughout the world, workers in developing countries are among those who are most vulnerable to and who face the greatest risk from occupational health hazards.

Occupational Health Effects are Different from Those Seen in Developed Countries

It is important to obtain data on health effects for prevention and for prioritization of approaches to solve occupational health problems. However, most of the available morbidity data may not be applicable for developing countries, as they originate from the developed countries.

In developing countries, the nature of the occupational health effects from workplace hazards may be different from those in the developed countries. Overt occupational diseases such as chemical poisonings and the pneumoconioses, which are caused by exposures to high levels of workplace toxins, are still encountered in significant numbers in developing countries, while these problems may have been substantially reduced in the developed countries.

For example, in the case of pesticide poisoning, acute health effects and even deaths from high exposures are a greater immediate concern in developing agricultural countries, as compared to the long-term health effects from low dose exposure to pesticides, which might be a more important issue in the developed countries. In fact, the morbidity burden from acute pesticide poisoning in some developing countries, such as Sri Lanka, may even surpass that of traditional public health problems such as diphtheria, whooping cough and tetanus.

Thus, some surveillance of occupational health morbidity is required from the developing countries. The information would be useful for the assessment of the magnitude of the problem, prioritization of plans to cope with the problems, allocation of resources and for subsequent evaluation of the impact of interventions.

Unfortunately, such surveillance information is often lacking in the developing countries. It should be recognized that surveillance programmes in developed countries may be inappropriate for developing countries, and such systems probably cannot be adopted in their entirety for developing countries because of the various problems which may impede surveillance activities.

Problems of Surveillance in Developing Countries

While the need for surveillance of occupational safety and health problems exists in developing countries, the actual implementation of surveillance is often fraught with difficulties.

The difficulties may arise because of poor control of industrial development, the absence of, or an inadequately developed infrastructure for, occupational health legislation and services, insufficiently trained occupational health professionals, limited health services and poor health reporting systems. Very often the information on the workforce and general population may be lacking or inadequate.

Another major problem is that in many developing countries, occupational health is not accorded a high priority in national development programmes.

Activities in Occupational Health and Safety Surveillance

Surveillance of occupational safety and health may involve activities such as the monitoring of dangerous occurrences at work, work injury and work fatalities. It also includes surveillance of occupational illness and surveillance of the work environment. It is probably easier to collect information on work injury and accidental death at work, since such events are fairly easily defined and recognized. In contrast, surveillance of the health status of the working population, including occupational diseases and the state of the work environment, is more difficult.

The rest of this article will therefore deal mainly with the issue of surveillance of occupational illness. The principles and approaches which are discussed can be applied to the surveillance of work injuries and fatalities, which are also very important causes of morbidity and mortality among workers in developing countries.

Surveillance of workers’ health in developing countries should not be limited only to occupational diseases, but should also be for general diseases of the working population. This is because the main health problems among workers in some developing countries in Africa and Asia may not be occupational, but may include other general diseases such as infectious diseases—for example, tuberculosis or sexually transmitted diseases. The information collected would then be useful for planning and allocation of health care resources for the promotion of health of the working population.

Some Approaches to Overcome the Problems of Surveillance

Which types of occupational health surveillance are appropriate in developing countries? In general, a system with simple mechanisms, employing available and appropriate technology, would be best suited for developing countries. Such a system should also take into account the types of industries and work hazards which are important in the country.

Utilization of existing resources

Such a system may utilize the existing resources such as the primary health care and environmental health services. For example, occupational health surveillance activities can be integrated into the current duties of primary health care personnel, public health inspectors and environmental engineers.

For this to happen, primary health care and public health personnel have first to be trained to recognize illness which may be related to the work, and even to perform simple assessments of unsatisfactory workplaces in terms of occupational safety and health. Such personnel should, of course, receive adequate and appropriate training in order to perform these tasks.

The data on conditions of work and illness arising from work activities can be collated while such persons conduct their routine work in the community. The information collected can be channelled to regional centres, and ultimately to a central agency responsible for the monitoring of conditions of work and occupational health morbidity that is also responsible for acting on these problems.

Registry of factories and work processes

A registry of factories and work processes, as opposed to a disease registry, could be initiated. This registry would obtain information from the registration stage of all factories, including work processes and materials used. The information should be updated periodically when new work processes or materials are introduced. Where, in fact, such registration is required by national legislation, it needs to be enforced in a comprehensive manner.

However, for small-scale industries, such registration is often bypassed. Simple field surveys and assessments of the types of industry and the state of working conditions could provide basic information. The persons who could perform such simple assessments could again be the primary health care and public health personnel.

Where such a registry is in effective operation, there is also a need for periodic update of the data. This could be made compulsory for all registered factories. Alternatively, it may be desirable to request an update from factories in various high-risk industries.

Notification of occupational diseases

Legislation for notification of selected occupational health disorders could be introduced. It would be important to publicize and educate people on this matter before implementation of the law. Questions such as what diseases should be reported, and who should be the persons responsible for notification, should first be resolved. For example, in a developing country like Singapore, physicians who suspect the occupational diseases listed in table 1 have to notify the Ministry of Labour. Such a list has to be tailored to the types of industry in a country, and be revised and updated periodically. Furthermore, the persons responsible for notification should be trained to recognize, or at least to suspect, the occurrence of the diseases.

Table 1. Sample list of notifiable occupational diseases

Continuous follow-up and enforcement action is needed to ensure the success of such notification systems. Otherwise, gross underreporting would limit their usefulness. For example, occupational asthma was first made notifiable and compensable in Singapore in 1985. An occupational lung disease clinic was also set up. Despite these efforts, a total of only 17 cases of occupational asthma were confirmed. This can be contrasted with the data from Finland, where there were 179 reported cases of occupational asthma in 1984 alone. Finland’s population of 5 million is only about twice that of Singapore. This gross under-reporting of occupational asthma is probably due to the difficulty in diagnosing the condition. Many doctors are unfamiliar with the causes and features of occupational asthma. Hence, even with the implementation of compulsory notification, it is important to continue to educate the health professionals, employers and employees.

When the notification system is initially implemented, a more accurate assessment of the prevalence of the occupational disease can be made. For example, the number of notifications of noise-induced hearing loss in Singapore increased six-fold after statutory medical examinations were introduced for all noise-exposed workers. Subsequently, if the notification is fairly complete and accurate, and if a satisfactory denominator population could be obtained, it may even be possible to estimate the incidence of the condition and its relative risk.

As in many notification and surveillance systems, the important role of notification is to alert the authorities to index cases at the workplace. Further investigations and workplace interventions, if necessary, are required follow-up activities. Otherwise, the efforts of notification would be wasted.

Other sources of information

Hospital and outpatient health information is often underutilized in the surveillance of occupational health problems in a developing country. Hospitals and outpatient clinics can and should be incorporated into the notification system for specific diseases, such as acute work-related poisonings and injuries. The data from these sources would also provide an idea of the common health problems among workers, and can be used for the planning of workplace health promotion activities.

All this information is usually routinely collected, and few extra resources are required to direct the data to the occupational health and safety authorities in a developing country.

Another possible source of information would be the compensation clinics or tribunals. Finally, if the resources are available, some regional occupational medicine referral clinics might also be initiated. These clinics could be staffed by more qualified occupational health professionals, and would investigate any suspected work-related illness.

Information from existing disease registries should also be utilized. In many larger cities of developing countries, cancer registries are in place. Though the occupational history obtained from these registries may not be complete and accurate, it is useful for preliminary monitoring of broad occupational groups. Data from such registries will be even more valuable if registers of workers exposed to specific hazards are available for cross-matching.

The role of data linkage

While this may sound attractive, and has been employed with some success in some developed countries, this approach may not be appropriate or even possible in developing countries at present. This is because the infrastructure required for such a system is often not available in developing countries. For example, disease registries and workplace registers may not be available or, if they exist, may not be computerized and easily linked.

Help from international agencies

International agencies such as the International Labour Organization, the World Health Organization and bodies such as the International Commission on Occupational Health can contribute their experience and expertise in overcoming common problems of occupational health and safety surveillance in a country. In addition, training courses as well as training opportunities for primary care persons may be developed or offered.

Sharing of information from regional countries with similar industries and occupational health problems is also often useful.

Summary

Occupational safety and health services are important in developing countries. This is especially so in view of the rapid industrialization of the economy, the vulnerable work population and the poorly controlled health hazards faced at work.

In the development and delivery of occupational health services in these countries, it is important to have some type of surveillance of occupational ill health. This is necessary for the justification, planning and prioritization of occupational health legislation and services, and the evaluation of the outcome of these measures.

While surveillance systems are in place in the developed countries, such systems may not always be appropriate for developing countries. Surveillance systems in developing countries should take into account the type of industry and hazards which are important in the country. Simple surveillance mechanisms, employing available and appropriate technology, are often the best options for developing countries.

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Systems of workplace injury and illness surveillance constitute a critical resource for management and reduction of occupational injuries and illnesses. They provide essential data which can be used to identify workplace problems, develop corrective strategies and thus prevent future injuries and illnesses. To accomplish these goals effectively, surveillance systems must be constructed which capture the characteristics of workplace injuries in considerable detail. To be of maximum value, such a system should be able to provide answers to such questions as which workplaces are the most hazardous, which injuries produce the most time lost from work and even what part of the body is injured most frequently.

This article describes the development of an exhaustive classification system by the Bureau of Labor Statistics of the United States Department of Labor (BLS). The system was developed to meet the needs of a variety of constituencies: state and federal policy analysts, safety and health researchers, employers, employee organizations, safety professionals, the insurance industry and others involved in promoting safety and health in the workplace.

Background

For a number of years, the BLS has collected three basic types of information concerning an occupational injury or illness:

• industry, geographic location of the incident and any associated lost workdays

• characteristics of the affected employee, such as age, gender and occupation

• how the incident or exposure occurred, the objects or substances involved, the nature of the injury or illness and part of the body affected.

The previous classification system, though useful, was somewhat limited and did not fully meet the needs described above. In 1989 it was decided that a revision of the existing system was in order that would best suit the needs of the varied users.

The Classification System

A BLS task force was organized in September 1989 to establish requirements for a system that would “accurately describe the nature of the occupational safety and health problem” (OSHA 1970). This team worked in consultation with safety and health specialists from the public and private sectors, with the goal of developing a revamped and expanded classification system.

Several criteria were established governing the individual code structures. The system must have a hierarchical arrangement to allow maximum flexibility for varied users of occupational injury and illness data. The system should be, to the extent possible, compatible with the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) of the WHO (1977). The system should meet the needs of other government agencies involved in the safety and health arena. Finally, the system must be responsive to the differing traits of nonfatal and fatal cases.

Drafts of the case characteristic classification structures were produced and released for comment in 1989 and again in 1990. The system included nature of injury or illness, part of body affected, source of injury or illness, event or exposure structures and secondary source. Comments were received and incorporated from bureau staff, state agencies, Occupational Safety and Health Administration, Employment Standards Administration and NIOSH, after which the system was ready for an onsite test.

Pilot testing of the structures for compiling data for nonfatal injuries and illnesses, as well as the operational application in the Census of Fatal Occupational Injuries, was conducted in four states. Test results were analysed and revisions completed by the fall of 1991.

The final 1992 version of the classification system consists of five case characteristic code structures, an occupational code structure and an industry code structure. The Standard Industrial Classification Manual is used to classify industry (OMB 1987), and the Bureau of the Census Alphabetical Index of Occupations for coding occupation (Bureau of the Census 1992). The BLS Occupational Injury and Illness Classification System (1992) is used to code the following five characteristics:

• nature of injury or illness

• part of body affected

• event or exposure

• source of injury or illness

• secondary source of injury or illness.

Besides numerical codes that represent specific conditions or circumstances, each code structure includes aids to assist in identification and selection of the proper code. These aids include: definitions, rules of selection, descriptive paragraphs, alphabetical listings and edit criteria for each of the structures. The rules of selection offer guidance to choose the appropriate code uniformly when two or more code selections are possible. The descriptive paragraphs provide additional information about the codes such as what is included or excluded in a particular code. For instance, the code for eye includes the eyeball, the lens, the retina and the eyelashes. The alphabetical listings can be used to quickly find the numerical code for a specific characteristic, such as medical terminology or specialized machinery. Finally, edit criteria are quality-assurance tools that can be used to determine which code combinations are incorrect prior to final selection.

Nature of injury or illness codes

The nature of injury or illness code structure describes the principal physical characteristic of the worker’s injury or illness. This code serves as the basis for all other case classifications. Once the nature of injury or illness has been identified, the remaining four classifications represent the circumstances associated with that particular outcome. The classification structure for nature of injury of illness contains seven divisions:

• traumatic injuries and disorders

• systemic diseases or disorders

• infectious and parasitic diseases

• neoplasms, tumours and cancer

• symptoms, signs and ill-defined conditions

• other conditions or disorders

• multiple diseases, conditions or disorders.

Before finalizing this structure, two similar classifications systems were evaluated for possible adoption or emulation. Because the American National Standards Institute (ANSI) Z16.2 standard (ANSI 1963) was developed for use in accident prevention, it does not contain a sufficient number of illness categories for many agencies to accomplish their missions.

The ICD-9-CM, designed for classifying morbidity and mortality information and used by a large portion of the medical community, provides the required detailed codes for illnesses. However, technical knowledge and training requirements for users and compilers of these statistics made this system prohibitive.

The final structure arrived at is a hybrid which combines the application method and rules of selection from the ANSI Z16.2 with the basic divisional organization from the ICD-9-CM. With few exceptions, divisions in the BLS structure can be directly mapped to the ICD-9-CM. For example, the BLS division identifying infectious and parasitic diseases maps directly to Chapter 1, Infectious and Parasitic Diseases, of the ICD-9-CM.

The first division in the BLS nature of injury or illness structure classifies traumatic injuries and disorders, effects of external agents and poisoning, and corresponds to Chapter 17 of the ICD-9-CM. Outcomes in this division are generally the result of a single incident, event or exposure, and include conditions such as fractures, bruises, cuts and burns. In the occupational environment, this division accounts for the great majority of reported cases.

Several situations required careful consideration when establishing rules to select codes in this division. Review of fatality cases revealed difficulties in coding certain types of fatal injuries. For example, fatal fractures usually involve direct or indirect mortal damage to a vital organ, such as the brain or spinal column. Specific coding categories and instructions were required to note the mortal damage associated with these types of injuries.

Gunshot wounds constitute a separate category with special instructions for those instances in which such wounds also resulted in amputations or paralysis. In keeping with an overall philosophy of coding the most serious injury, paralysis and amputations take precedence over less serious damage from a gunshot wound.

Responses to questions on employer reporting forms concerning what happened to the injured or ill worker do not always adequately describe the injury or illness. If the source document indicates only that the employee “hurt his back”, it is not appropriate to assume this is a sprain, strain, dorsopathy or any other specific condition. To solve the problem, individual codes were established for non-specific descriptions of injury or illness like “sore,” “hurt” and “pain”.

Finally, this division has a section of codes to classify the most frequently occurring combinations of conditions that result from the same incident. For example, a worker may suffer both scratches and bruises from a single incident.

Five of the remaining divisions of this classification structure were devoted to identification of occupational diseases and disorders. These sections present codes for specific conditions that are of paramount interest to the safety and health community. In recent years, a growing number of diseases and disorders have been linked to the work environment but were seldom represented in the existing classification structures. The structure has a vastly expanded list of specific diseases and disorders such as carpal tunnel syndrome, Legionnaire’s disease, tendonitis and tuberculosis.

Part of body affected

The part of body affected classification structure specifies the part of the body which was directly affected by the injury or illness. When linked with the nature of injury or illness code, it provides a more complete picture of the damage incurred: amputated finger, lung cancer, fractured jaw. This structure consists of eight divisions:

• head

• neck, including throat

• trunk

• upper extremities

• lower extremities

• body systems

• multiple body parts

• other body parts.

Three issues surfaced during evaluation of redesign options for this theoretically simple and straightforward piece of the classification system. The first was the merit of coding external location (arm, trunk, leg) of the injury or illness versus the affected internal site (heart, lungs, brain).

Test results indicated that coding the internal part of body affected was appropriate for diseases and disorders, but extremely confusing when applied to many traumatic injuries such as cuts or bruises. The BLS developed a policy of coding the external location for most traumatic injuries and coding internal locations, where appropriate, for diseases.

The second issue was how to handle diseases that affect more than one body system simultaneously. For instance, hypothermia, a condition of low body temperature due to exposure to the cold, can affect the nervous and endocrine systems. Because it is difficult for nonmedical personnel to determine which is the appropriate choice, this could lead to a tremendous amount of research time with no clear resolution. Therefore, the BLS system was designed with a single entry, body systems, that categorizes one or more body systems.

Adding detail to identify typical combinations of parts in the upper extremities and the lower extremities was the third major enhancement to this code structure. These combinations, such as hand and wrist, proved to be supportable by the source documents.

Event or exposure

The event or exposure code structure describes the manner in which the injury or illness was inflicted or produced. The following eight divisions were created to identify the primary method of injury or exposure to a harmful substance or situation:

• contact with objects and equipment

• falls

• bodily reaction and exertion

• exposure to harmful substances or environments

• transportation accidents

• fires and explosions

• assaults and violent acts

• other events or exposures.

Injury-producing incidents are frequently composed of a series of events. To illustrate, consider what occurs in a traffic accident: A car hits a guard-rail, crosses the median strip and collides with a truck. The driver has several injuries from striking parts of the car and being struck by broken glass. If the micro-events—such as hitting the windshield or being struck by flying glass—were coded, the overall fact that the person was in a traffic accident could be missed.

In these multiple event instances, the BLS designated several occurrences to be considered primary events and to take precedence over other micro-events associated with them. These primary events included:

• assaults and violent acts

• transportation accidents

• fires

• explosions.

An order of precedence was established within these groups as well because they frequently overlap—for example, a highway accident can involve a fire. This order of precedence is the order which they appear in the above list. Assaults and violent acts were assigned first precedence. Codes within this division generally describe the type of violence, while the weapon is addressed in the source code. Transportation accidents are next in precedence, followed by fires and explosions.

These last two events, fires and explosions, are combined in a single division. Because the two often occur simultaneously, an order of precedence between the two had to be established. In accordance with the ICD-9 Supplementary Classification of External Causes, fires were given precedence over explosions (USPHS 1989).

Selection of codes for inclusion in this structure was influenced by the emergence of non-contact disorders that are associated with the activities and ergonomics of the job. These cases typically involve nerve, muscle or ligament damage brought about by exertion, repetitive motion and even simple body motions such as when the worker’s back “goes out” when reaching over to pick up an item. Carpal tunnel syndrome is now widely recognized to be tied to repetitive actions such as key entry, typing, cutting actions and even operating a cash register. The division bodily reaction and exertion identifies these non-contact, or non-impact, incidents.

The event division “exposure to harmful substances or environments” distinguishes the specific method of exposure to toxic or harmful substances: inhalation, skin contact, ingestion or injection. A separate category to identify the transmission of an infectious agent through a needle stick was developed. Also included in this division are other non-impact incidents in which the worker was harmed by electric power or by environmental conditions, such as extreme cold.

Contact with objects and equipment and falls are the divisions that will capture most impact events that injure workers.

Source of injury or illness

The source of injury or illness classification code identifies the object, substance, bodily motion or exposure which directly produced or inflicted the injury or illness. If a worker is cut on the head by a falling brick, the brick is the source of injury. There is a direct relationship between the source and the nature of the injury or illness. If a worker slips on oil and falls to the floor, breaking an elbow, the fracture is produced by hitting the floor, so the floor is source of injury. This code system contains ten divisions:

• chemicals and chemical products

• containers

• furniture and fixtures

• machinery

• parts and materials

• persons, plants, animals and minerals

• structures and surfaces

• tools, instruments and equipment

• vehicles

• other sources.

The general definitions and coding concepts for the new BLS Source Classification Structure were carried over from the ANSI Z16.2 classification system. However, the task of developing a more complete and hierarchical code listing was initially daunting, since virtually any item or substance in the world can qualify as a source of injury or illness. Not only can everything in the world qualify as source, so can pieces or parts of everything in the world. To add to the difficulty, all candidates for inclusion in the source codes had to be grouped into only ten divisional categories.

Examination of historical data on work injuries and illness identified areas where the previous code structure was inadequate or out of date. The machinery and tools sections needed expansion and updating. There was no code for computers. Newer technology had made the list of power tools obsolete, and many items listed as nonpowered tools were now almost always powered: screwdrivers, hammers and so on. There was a demand from users to expand and update the list of chemicals in the new structure. The US Occupational Safety and Health Administration requested expanded detail for a variety of items, including several types of scaffolds, forklifts and construction and logging machines.

The most difficult aspect of developing the source structure was organizing the items required for inclusion into distinct divisions and groups within the division. To add to the difficulty, the source code categories had to be mutually exclusive. But no matter what categories were developed, there were many items that logically fit in two or more divisions. For example, there was general agreement that there should be separate categories for vehicles and for machines. However, reviewers disagreed about whether certain equipment such as road pavers or forklifts, belonged with machines or vehicles.

Another area of debate developed on how to group the machines within the machinery division. The options included associating machines with a process or an industry (for example, agricultural or garden machines), grouping them by function (printing machines, heating and cooling machinery) or by type of object processed (metal working, woodworking machines). Unable to find a single solution which was workable for all types of machines, the BLS compromised with a listing that uses an industry function for some groups (agricultural machines, construction and logging machines), general function for other groups (material handling machines, office machines), and some material-specific functional groupings (metalworking, woodworking). Where the possibility of overlap occurred, such as a woodworking machine used for construction work, the structure defined the category to which it belonged, to keep the codes mutually exclusive.

Special codes were added to capture information on injuries and illnesses occurring in the health care industry, which has emerged as one of the largest employment sectors in the United States, and one with serious safety and health problems. As an example, many of the participating state agencies recommended inclusion of a code for patients and residents of health care facilities, since nurses and health aides can be hurt while trying to lift, move or otherwise care for their patients.

Secondary source of injury or illness

The BLS and other data users recognized that the occupational injury and illness source classification structure captures the object that produced the injury or illness but sometimes fails to identify other important contributors to the event. In the previous system, for example, if a worker was struck by a piece of wood that flew off a jammed saw, the wood was the source of injury; the fact that a power saw was involved was lost. If a worker was burned by fire, the flame was selected as the source of injury; one could not also identify the source of the fire.

To make up for this potential loss of information, the BLS developed a secondary source of injury or illness which “identifies the object, substance, or person that generated the source or injury or illness or that contributed to the event or exposure”. Within the specific rules of selection for this code, the emphasis is on identifying the machines, tools, equipment or other energy-generating substances (such as flammable liquids) that are not identified through source classification. In the first example noted above, the power saw would be the secondary source, since it threw out the piece of wood. In the latter example, the substance that ignited (grease, gasoline and so on) would be named as the secondary source.

Implementation Requirements: Review, Verification and Validation

Establishing a comprehensive classification system is only one step in assuring that accurate information concerning workplace injuries and illnesses is captured and available for use. It is important that workers in the field understand how to apply the coding system accurately, uniformly and according to the system design.

The first step in quality assurance was to thoroughly train those who will be assigning the classification system codes. Beginning, intermediate and advanced courses were developed to assist in uniform coding techniques. A small group of trainers was charged with delivering these courses to concerned personnel throughout the United States.

Electronic edit checks were devised to assist in the review, verification and validation process for the case characteristic and demographic estimates. Criteria of what can and cannot be combined were identified and an automated system to identify those combinations as errors was put into place. This system has over 550 groups of cross check which verify that the incoming data meet quality checks. For example, a case that identified carpal tunnel syndrome as affecting the knee would be deemed an error. This automated system also identifies invalid codes, that is, codes that do not exist in the classification structure.

Clearly, these edit checks cannot be sufficiently stringent to capture all suspect data. The data should be examined for overall reasonableness. For example, over the years of collecting similar data for the part of body, nearly 25% of the cases named the back as the affected area. This gave review staff a benchmark for validating data. A review of cross tabulations for overall sensibility also gives insight into how well the classification system was applied. Finally, special rare events, such as work-related tuberculosis, should be validated. One important element of a comprehensive validation system could involve recontacting the employer to insure the accuracy of the source document, although this requires additional resources.

Examples

Selected examples from each of the four illness and injury classification coding systems are shown in table 1 in order to illustrate the level of detail and the resulting richness of the final system. The power of the system as a whole is demonstrated in table 2, which shows a variety of characteristics that were tabulated for one set of related injury types—falls. In addition to total falls, the data are further subdivided into falls on the same level, falls to a lower level and jumping to a lower level. It can be seen, for instance, that falls were most likely to occur to workers age 25 to 34 years old, to operators, fabricators and labourers, to workers in the manufacturing industries and to workers with less than five years of service to their current employer (data not shown). The accident was most often associated with work on a floor or ground surface, and the subsequent injury was most likely to be a sprain or strain affecting the back, resulting in the worker spending more than one month away from work.

Table 1. Nature of injury or illness code—Examples

Nature of injury or illness code-Examples

0* Traumatic Injuries and Disorders

08*                                    Multiple traumatic injuries and disorders

080                              Multiple traumatic injuries and disorders, unspecified

081                              Cuts, abrasions, bruises

082                              Sprains and bruises

083                              Fractures and burns

084                              Fractures and other injuries

085                              Burns and other injuries

086                              Intracranial injuries and injuries to internal organs

089                              Other combinations of traumatic injuries and disorders, n.e.c.

Event or exposure code-Examples

1* Falls

11*                                   Fall to lower level

113                              Fall from ladder

114                              Fall from piled or stacked material

115*                            Fall from roof

1150                  Fall from roof, unspecified

1151                  Fall through existing roof opening

1152                  Fall through roof surface

1153                  Fall through skylight

1154                  Fall from roof edge

1159                  Fall from roof, n.e.c.

116                    Fall from scaffold, staging

117                    Fall from building girders or other structural steel

118                    Fall from nonmoving vehicle

119                    Fall to lower level, n.e.c.

Source of injury or illness code-Examples

7*Tools, instruments and equipment

72*                                     Handtools-powered

722*                              Cutting handtools, powered

7220                   Cutting handtools, powered, unspecified

7221                   Chainsaws, powered

7222                   Chisels, powered

7223                    Knives, powered

7224                    Saws, powered, except chainsaws

7229                    Cutting handtools, powered, n.e.c.

723*                               Striking and nailing handtools, powered

7230                    Striking handtools, powered, unspecified

7231                    Hammers, powered

7232                    Jackhammers, powered

7233                    Punches, powered

Part of body affected code-Examples

2* Trunk

23*                                   Back, including spine, spinal cord

230                              Back, including spine, spinal cord, unspecified

231                              Lumbar region

232                              Thoracic region

233                              Sacral region

234                              Coccygeal region

238                              Multiple back regions

239                              Back, including spine, spinal cord, n.e.c.

* = division, major group, or group titles; n.e.c. = not elsewhere classified.

Table 2. Number and percentage of nonfatal occupational injuries and illnesses with days away from work involving falls, by selected worker and case characteristics, US 1993¹

 ¹ Days away from work cases include those which result in days away from work with or without restricted work activity.

² Excludes farms with fewer than 11 employees.

³ Data conforming to OSHA definitions for mining operators in coal, metal, and nonmetal mining and for employers in railroad transportation are provided to BLS by the Mine Safety and Health Administration, U.S. Department of Labor; the Federal Railroad Administration and U.S. Department of Transportation. Independent mining contractors are excluded from the coal, metal, and nonmetal mining industries.

NOTE: Because of rounding and data exclusion of nonclassifiable responses, data may not sum to the totals. Dashes indicate data that do not meet publication guidelines. The survey estimates of occupational injuries and illnesses are based on a scientifically selected sample of employers. The sample used was one of many possible samples, each of which could have produced different estimates. The relative standard error is a measure of the variation in the sample estimates across all possible samples that could have been selected. The percent relative standard errors for the estimates included here range from less than 1 per cent to 58 per cent.
Survey of Occupational Injuries and Illnesses, Bureau of Labor Statistics, US Department of Labor, April 1995.

It is clear that data such as these can have an important impact upon development of programmes for work-related accident and disease prevention. Even so, they do not indicate which occupations or industries are the most hazardous, since some very dangerous occupations may have small numbers of workers. Determination of levels of risk associated with particular occupations and industries is explained in the accompanying article “Risk analysis of nonfatal workplace injuries and illnesses”.

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The United States Bureau of Labor Statistics routinely classifies nonfatal workplace injuries and illnesses by worker and case characteristics, using data from the US Survey of Occupational Injuries and Illnesses. While these counts identify groups of workers who experience large numbers of workplace injuries, they do not measure risk. Thus a particular group may sustain many workplace injuries simply because of the large number of workers in that group, and not because the jobs performed are especially hazardous.

In order to quantify actual risk, data on workplace injuries must be related to a measure of exposure to risk, such as number of hours worked, a labour supply measure which may be available from other surveys. The rate of nonfatal workplace injuries for a group of workers may be calculated by dividing the number of injuries recorded for that group by the number of hours worked during the same time period. The rate obtained this way represents the risk of injury per hour of work:

A convenient way of comparing the risk of injury among various groups of workers is to compute the relative risk:

The reference group may be a special group of workers, such as all managerial and professional specialty workers. Alternatively, it might consist of all workers. In any case, the relative risk (RR) corresponds to the rate ratio commonly used in epidemiological studies (Rothman 1986). It is algebraically equivalent to the percentage of all injuries which occur to the special group divided by the percentage of hours accounted for by the special group. When the RR is greater than 1.0, it indicates that members of the selected group are more likely to sustain injuries than members of the reference group; when the RR is less than 1.0, it indicates that, on the average, members of this group experience fewer injuries per hour.

The following tables show how indexes of relative risk for different groups of workers can identify those at greatest risk of workplace injury. The injury data are from the 1993 Survey of Occupational Injuries and Illnesses (BLS 1993b) and measure the number of injuries and illnesses with days away from work. The calculation relies upon estimates of annual hours worked taken from the microdata files of the US Bureau of the Census Current Population Surveys for 1993, which is obtained from household surveys (Bureau of the Census 1993).

Table 1 presents data by occupation on the share of workplace injuries, the share of hours worked and their ratio, which is the RR for injuries and illnesses with days away from work. The reference group is taken to be “All nonfarm private industry occupations” with workers of age 15 and older, which comprises 100%. As an example, the group “Operators, fabricators and labourers” experienced 41.64% of all injuries and illnesses, but contributed only 18.37% of the total hours worked by the reference population. Therefore, the RR for “Operators, fabricators and labourers” is 41.64/18.37 = 2.3. In other words, workers in this group of occupations have on average 2.3 times the injury/illness rate of all nonfarm private industry workers combined. Furthermore, they are about 11 times as likely to sustain a serious injury as employees in a managerial or professional specialty.

Table 1. Risk of occupational injuries and illnesses

¹ Percentage of injuries and illnesses, hours worked and index of relative risk for occupational injuries and illnesses with days away from work, by occupation, US nonfarm private industry employees 15 years and over, 1993.
² Excludes private household workers and protective service workers in the public sector
³ Excludes protective service workers in the public sector
⁴ Excludes workers in agricultural production industries
Sources: BLS Survey of Occupational Injuries and Illnesses, 1993; Current Population Survey, 1993.

The various occupational groups may be ranked according to degree of risk simply by comparing their RR indices. The highest RR in the table (3.6) is associated with “handlers, equipment cleaners, helpers and labourers”, while the group at lowest risk is managerial and professional specialty workers (RR = 0.2). More refined interpretations may be made. While the table suggests that workers with lower levels of skills are in jobs with higher risks of injury and illness, even among blue-collar occupations the injury and illness rate is higher for less-skilled operators, fabricators and labourers compared to precision production, craft and repair workers.

In the above discussion, the RRs have been based upon all injuries and illnesses with days away from work, since these data have long been readily available and understood. Using the extensive and newly developed coding structure of the Survey of Occupational Injuries and Illnesses, researchers may now examine specific injuries and illnesses in detail.

As an example, table 2 shows the RR for the same set of occupation groupings, but restricted to the single outcome “Repetitive Motion Conditions” (event code 23) with days away from work, by occupation and gender. Repetitive motion conditions include carpal tunnel syndrome, tendonitis and certain strains and sprains. The group most severely affected by this type of injury is quite clearly female machine operators, assemblers and inspectors (RR = 7.3), followed by female handlers, equipment cleaners, helpers and labourers (RR = 7.1).

Table 2. Index of relative risk for repetitive motion conditions with days away from work, by occupation and gender, US nonfarm private industry employees 15 years and over, 1993

¹ Excludes private household workers and protective service workers in the public sector
² Excludes protective service workers in the public sector
³ Excludes workers in agricultural production industries
Note: Long dashes — indicate that data do not meet publication guidelines.
Source: Calculated from the BLS Survey of Occupational Injuries and Illnesses, 1993, and Current Population Survey, 1993.

The table shows striking differences in the risk of repetitive motion conditions that depend on the gender of the worker. Overall, a woman is 2.5 times as likely as a man to lose work due to repetitive motion illness (2.5 = 1.5/0.6). However, this difference does not simply reflect a difference in the occupations of men and women. Women are at higher risk in all of the major occupational groups, as well as the less aggregated occupational groupings reported in the table. Their risk relative to men is especially high in sales and blue-collar occupations. Women are six times as likely as men to lose work time from repetitive motion injuries in sales and in precision production, craft and repair occupations.

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The German Berufsgenossenschaften (BG)

Under the social insurance system in Germany, statutory accident insurance covers the results of accidents at work and accidents on the way to and from work, as well as occupational diseases. This statutory accident insurance is organized into three areas:

• industrial accident insurance (represented by the BGs)

• agricultural accident insurance

• public sector’s own accident insurance scheme.

The 35 Berufsgenossenschaften (BG) cover the various branches of the industrial economy in Germany. They are responsible for 39 million employees insured in 2.6 million enterprises. Every person in a work, service or training position is insured, regardless of age, sex or income level. Their umbrella organization is the Central Federation of the Berufsgenossenschaften (HVBG).

By law, the BG is responsible for using all appropriate means to prevent workplace accidents and occupational diseases, to provide effective first aid and optimal medical, occupational and social rehabilitation, and to pay benefits to the injured and sick, and to survivors. Thus prevention, rehabilitation and compensation are all under one roof.

The premiums to finance these benefits are paid exclusively by the employers. In 1993 all industrial employers paid on average DM 1.44 to the BG for every DM 100 wages, or 1.44%. In all, the premiums came to DM 16 billion (US billion used—one thousand million), of which about 80% was spent for rehabilitation and pensions. The remainder was used primarily for prevention programmes.

Occupational Safety and Health Protection

The employer is responsible for the health and safety of the employee at work. The legal scope of this responsibility is set by government in laws and ordinances, and in the protective labour regulations of the industrial BGs, which complete and concretize governmental protective labour law for each branch of industry. The system of prevention of the BGs is notable for its orientation to actual practice, its constant adaptation to the needs of the industry and to the state of technology, as well as for its effective support of the employer and the employee.

The BGs’ tasks of prevention, which are primarily carried out by the Technical Inspection Service (TAD) of the BG and the Occupational Medical Service (AMD), include:

• advising and motivating the employer

• supervising industrial occupational protective measures

• occupational medical care

• informing and training company staff

• safety checking on appliances and equipment

• initiating, carrying out and financing research.

Responsibility for implementing industrial occupational protection lies with the employer, who is legally obliged to hire appropriately qualified personnel to assist in occupational protection. These are specialists in work safety (safety officers, safety technicians and safety engineers) and company doctors. In companies with more than 20 employees, one or more safety representatives must be hired. The scope of the responsibility of the company for occupational safety specialists and company doctors is set by trade association regulations that are specific to the branch of industry and degree of hazard. In companies where an occupational safety specialist or a company doctor is employed, the employer must organize an occupational safety committee, made up of one company representative, two workers’ representatives, the company doctor, and occupational safety specialists and safety representatives. First-aid personnel, whose training is directed by the BG, also belong to the company occupational safety organization.

Occupational medical care has a special significance. Every employee who is at risk for a specific type of health threat at the workplace is examined in a uniform manner, and the results of the examination are assessed according to stated guidelines. In 1993 approximately four million occupational preventive medical examinations were carried out by specially authorized doctors. Lasting health concerns were ascertained in less than 1% of the examinations.

Employees who work with hazardous/carcinogenic materials also have a right to be medically examined even after the hazardous activity has been completed. The BGs have established services to be able to examine these employees. There are now three such services:

• Organizational Service for On-going Examinations (ODIN)

• Central Registration Service for Asbestos Dust-Endangered Employees (ZAs)

• Wismut Central Care Office (ZeBWis).

The three services cared for approximately 600,000 people in 1993. Collecting examination data assists in individual care and also helps improve scientific research for early detection of cancer cases.

Statistics on Workplace Accidents

Goal. The primary goal of collecting statistics on workplace accidents is to improve workplace safety by assessing and interpreting data on accident occurrences. These data are compiled from reports on workplace accidents; 5% to 10% of the accidents (approximately 100,000 accidents) are investigated each year by the Technical Inspection Services of the BGs.

Employers’ reporting responsibility. Every employer is obliged to report a workplace accident to his responsible BG within three days if the accident results in an incapacity to work for three calendar days or causes the death of the insured (“legally reportable workplace accident”). This includes accidents going to or from work. Accidents that cause only property damage or prevent the injured person from working for less than three days do not have to be reported. For reportable workplace accidents, a form “Accident Notification” (figure 1) is submitted by the employer. The time away from work is the significant factor for reporting purposes, regardless of the seriousness of the injury. Accidents that appear harmless must be reported if the injured person cannot work for longer than three days. This three-day requirement facilitates pursuing later claims. Failure to file an accident report, or filing one late, constitutes a violation of regulations that can be punished by the BG with a monetary fine of up to DM 5,000.

Figure 1. An example of an accident notification form

Notification by the attending physician. To optimize medical rehabilitation and to determine how long the employee is unable to work, the injured person receives treatment from a medical specialist selected for this work. The doctor is paid by the responsible industrial BG. Thus, the BG also receives notification of reportable workplace injuries from the doctor if the employer has failed to (promptly) file an accident report. The BG can then request the employer to file a workplace accident notification. This dual reporting system (employer and doctor) assures the BG of receiving knowledge of practically all reportable workplace accidents.

Using the information on the accident notification report and the medical report, the BG checks whether the accident is, in the legal sense, a workplace accident within its jurisdictional competence. On the basis of the medical diagnosis, the BG can, if needed, proceed immediately to ensuring optimal treatment.

A correct and complete description of the circumstances of the accident is especially important for prevention. This enables the BG’s Technical Inspection Service to draw conclusions about defective machinery and equipment that require immediate action to avoid further similar accidents. In the case of serious or fatal workplace accidents, regulations require the employer to immediately notify the BG. These occurrences are immediately investigated by the BG’s occupational safety experts.

In calculating a company’s premium, the BG takes into account the number and cost of workplace accidents that have taken place at this company. A bonus/malus procedure set by law is used in the calculation, and a portion of the company’s premium is determined by the company’s accident trend. This can lead to a higher or lower premium, thus creating financial incentives for employers to maintain safe workplaces.

Collaboration of the employees’ representatives and the safety representatives. Any accident report must also be signed by the workers’ council (Betriebsrat) and by the safety representatives (if these exist). The purpose of this rule is to inform the workers’ council and the safety representatives of the company’s overall accident situation, so that they can effectively exercise their collaborative rights in questions of workplace safety.

Compiling workplace accident statistics. On the basis of the information that the BG receives on a workplace accident from the accident report and the doctor’s report, the accounts are translated into statistical code numbers. The coding covers three areas, among others:

• description of the injured (age, sex, job)

• description of the injury (location of injury, type of injury)

• description of the accident (location, object causing the accident and circumstances of the accident).

Coding is performed by highly trained data specialists who are familiar with the organization of BG industries, utilizing a list of accident and injury codes which contains over 10,000 entries. In order to achieve the highest quality statistics, the classifications are regularly reworked, in order, for example, to adapt them to new technological developments. Furthermore, coding personnel are periodically retrained, and the data are subject to formal-logical and content-sensitive tests.

Uses of workplace accident statistics

An important task of these statistics is to describe the circumstances of the accident at the workplace. Table 1 portrays trends in reportable workplace accidents, new accident pension cases and fatal workplace accidents between 1981 and 1993. Column 3 (“New pension cases”) shows cases for which, because of the seriousness of the accident, a pension payment was first made by the industrial BGs in the given year.

Table 1. Occurrences of workplace accidents, Germany, 1981-93

Source: Central Federation of Berufsgenossenschaften (HVBG), Germany.

To judge the average accident risk of an insured, the number of workplace accidents is divided by the actual time worked, to produce an accident rate. The rate per one million hours worked is used for comparison internationally and across years. Figure 2 shows how this rate varied between 1981 and 1993.

Figure 2. Frequency of workplace accidents

Industry-specific accident statistics. In addition to describing general trends, workplace statistics can be broken down by industry. For example, one might ask, “How many workplace accidents with portable grinders in the metalworking trade were there in the last few years; how and where did they take place; and what injuries resulted?” Such analyses may be useful to many people and institutions, such as government ministries, supervisory officials, research institutes, universities, businesses and workplace safety experts (table 2).

Table 2. Workplace accidents with portable grinders in metalworking, Germany, 1984-93

Source: Central Federation of Berufsgenossenschaften (HVBG), Germany.

For example, table 2 shows that reportable workplace accidents with portable grinders in metalworking rose continuously from the middle of the 1980s to 1990. From 1990 to 1991 a considerable increase in the accident figures is to be noted. This is an artefact resulting from the inclusion, beginning in 1991, of figures encompassing the new borders of reunited Germany. (The earlier figures cover only the Federal Republic of Germany.)

Other data compiled from accident reports reveal that not all accidents with metalworking portable grinders take place primarily in companies in the metalworking industry. Portable grinders, which of course are often used as angle grinders to cut pipes, iron bars and other objects, are frequently employed on construction sites. Accordingly, nearly one-third of the accidents are concentrated in companies in the construction industry. Working with portable grinders in metalworking results mainly in head and hand injuries. The most common head injuries affect the eyes and the area surrounding the eyes, which are injured by broken pieces, splinters and flying sparks. The tool has a fast-spinning grinding wheel, and hand injuries result when the person using the portable machine loses control of it. The high number of eye injuries proves that the importance and obligation of wearing safety glasses while grinding metal with this portable machine must be emphasized within companies.

Comparison of accident rates within and between industries. Although in 1993 there were nearly 18,000 workplace accidents with portable grinders in metalworking, compared to only 2,800 workplace accidents with hand-held power saws in woodworking, one cannot automatically conclude that this machinery poses a greater risk to metalworkers. To assess accident risk for specific industries, the number of accidents must first be related to a measure of exposure to danger, such as hours worked (see “Risk analysis of nonfatal workplace injuries and illnesses” [REC05AE]). However, this information is not always available. Therefore, a surrogate rate is derived as the proportion which serious accidents make of all reportable accidents. Comparing the serious-injury proportions for portable grinders in metalworking and portable circular saws in woodworking demonstrates that portable circular saws have an accident seriousness rate ten times higher than portable grinders. For prioritizing workplace safety measures, this is an important finding. This type of comparative risk analysis is an important component of an overall industrial accident prevention strategy.

Occupational Disease Statistics

Definition and reporting

In Germany an occupational disease is legally defined as a disease whose cause can be traced to the occupational activity of the affected person. An official list of occupational diseases exists. Therefore, assessing whether a sickness constitutes an occupational disease is both a medical and legal question and is referred by public law to the BG. If an occupational disease is suspected, it is not sufficient to prove that the employee suffers from, for example, an eczema. Additional knowledge is required about substances used at work and their potential for harming the skin.

Compiling occupational disease statistics. Because the BGs are responsible for compensating workers with occupational diseases as well as for providing rehabilitation and prevention, they have a considerable interest in application of statistics derived from occupational disease reports. These applications include targeting preventive measures on the basis of identified high-risk industries and occupations, and also providing their findings to the public, the scientific community and political authorities.

To support these activities, the BGs introduced in 1975 a set of occupational disease statistics, which contain data on every occupational disease report and its final determination—whether recognized or denied—including the reasons for the decision at the level of the individual case. This data base contains anonymous data on:

• the person, such as sex, year of birth, nationality

• diagnosis

• hazardous exposures

• the legal decision, including outcome of claim, determination of disability and any further actions taken by the BGs.

Results of the occupational disease statistics. An important function of the occupational disease statistics is to track the occurrence of occupational diseases over time. Table 3 charts the notifications of suspected occupational disease, the number of recognized occupational disease cases overall and the payment of pensions, as well as the number of fatal cases between 1980 and 1993. It should be cautioned that these data are not easy to interpret, since definitions and criteria differ widely. Furthermore, during this time period the number of officially designated occupational diseases rose from 55 to 64. Also, the figures from 1991 encompass the new borders of reunited Germany, whereas the earlier ones cover the Federal Republic of Germany alone.

Table 3. Occurrences of occupational disease, Germany, 1980-93

Source: Central Federation of Berufsgenossenschaften (HVBG), Germany.

Example: infectious diseases. Table 4 shows the decline in the number of recognized cases of infectious diseases during the period 1980 to 1993. It specifically singles out viral hepatitis, for which one can clearly see that a strongly declining trend developed from approximately the mid-1980s in Germany, when employees at risk in the health service were given preventive inoculations. Thus occupational disease statistics can serve not only to find high rates of illnesses, but can also document the successes of protective measures. Declines in disease rates may of course have other explanations. In Germany, for example, the reduction in the number of cases of silicosis during the past two decades is chiefly a result of the decline in the number of jobs in mining.

Table 4. Infectious diseases recognized as occupational diseases, Germany, 1980-93

Source: Central Federation of Berufsgenossenschaften (HVBG), Germany.

Sources of Information

The HVBG, as umbrella organization for the BGs, centralizes the common statistics and produces analyses and brochures. Furthermore, the HVBG sees statistical information as an aspect of the overall information that must be available to carry out the broad range of mandated responsibilities of the accident insurance system. For this reason, the Central Information System of the BGs (ZIGUV) was formed in 1978. It prepares relevant literature and makes it available to the BGs.

Workplace safety as an interdisciplinary, comprehensive approach requires optimum access to information. The BGs in Germany have resolutely taken this path and thereby made a considerable contribution to the efficient workplace safety system in Germany.

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