The modern office may contain several types of reproduction machines. They range from the ubiquitous dry-process photocopier to the rather special-purpose blueprint machine, the fax and mimeograph machines, as well as other types of duplicators. Within this article, the different devices will be grouped according to broad technology classes. Since dry-process photocopiers are so widespread, they will receive the greatest attention.

Photocopiers and Laser Printers

Processing operations

Most steps in conventional electrophotography (xerography) are directly analogous to those in photography. In the exposure step, the printed page or photograph to be copied is illuminated by a flash of bright light, and the reflected image is focused by a lens onto an electrically charged, light-sensitive photoreceptor, which loses its charge wherever the light hits its surface. The light will have hit in the same pattern as on the surface being copied. Next, developer, generally composed of large carrier beads with small, electrostatically charged particles adhering to them, is transported to the photoreceptor by a cascading or magnetic conveying process. The charged, latent image on the photoreceptor is developed when the finely divided powder (known as toner, dry imager or dry ink) is electrostatically attracted, separates out of the developer and remains on the image. Finally, the toner that has adhered to the imaged areas is electrostatically transferred (printed) to a sheet of plain paper and permanently fused to it (fixed) by the application of heat, or heat and pressure. Residual toner is removed from the photoreceptor by a cleaning process and deposited into a waste toner sump. The photoreceptor is then prepared for the next imaging cycle. Since the imaged paper removes only toner from the developer, the carrier that supplied it to the image is recirculated back into the developer housing and mixed with fresh toner that is metered into the system from a replaceable toner supply bottle or cartridge.

Many machines apply both pressure and heat to the toner-on-paper image during a fusing process. The heat is supplied by a fusing roll, which contacts the toned surface. Depending on the characteristics of the toner and fuser materials, some toner may stick to the fuser surface rather than to the paper, resulting in a deletion of part of the image on the copy. In order to prevent this, a fuser lubricant, commonly a silicone-based fluid, is applied to the surface of the fuser roll.

In laser printing, the image is first converted to an electronic format; that is, it is digitized into a series of very small dots (pixels) by a document scanner, or a digital image may be created directly in a computer. The digitized image is then written onto the photoreceptor in the laser printer by a laser beam. The remaining steps are essentially those of conventional xerography, wherein the image on the photoreceptor is transformed to paper or other surfaces.

Some photocopiers use a process known as liquid development. This differs from the conventional, dry process in that the developer is generally a liquid hydrocarbon carrier in which finely divided toner particles are dispersed. Development and transfer are generally analogous to the conventional processes, except that the developer is washed over the photoreceptor and the wet copy is dried by the evaporation of residual liquid upon the application of heat or both heat and pressure.

Materials

The consumables associated with photocopying are toners, developers, fuser lubricants and paper. Although not generally considered as consumables, photoreceptors, fuser and pressure rolls and various other parts routinely wear out and need replacement, especially in high-volume machines. These parts are generally not considered to be customer replaceable, and require special knowledge for their removal and the adjustment. Many new machines incorporate customer replaceable units (CRUs), which contain the photoreceptor and developer in a self-contained unit which the customer can replace. In these machines, the fuser rolls and so on either last the life of the machine or require separate repair. In a move toward reduced service costs and greater customer convenience, some companies are moving towards increased customer reparability, where repair can be made with no mechanical or electrical hazard risk to the customer and will, at most, require a telephone call to a support centre for assistance.

Toners produce the image on the finished copy. Dry toners are fine powders composed of plastics, colourants and small quantities of functional additives. A polymer (plastic) is usually the major component of a dry toner; styrene-acrylic, styrene-butadiene and polyester polymers are common examples. In black toners, different carbon blacks or pigments are used as the colourant, while in colour copying, various dyes or pigments are employed. During the toner manufacturing process, the carbon black or colourant and the polymer are melt mixed and most of the colourant becomes encapsulated by the polymer. Dry toners may also contain internal and/or external additives which help determine the toner’s static charging and/or flow characteristics.

Wet-process toners are similar to dry toners in that they consist of pigments and additives inside a polymer coating. The difference is that those components are purchased as a dispersion in an isoparaffinic hydrocarbon carrier.

Developers are usually mixtures of toner and carrier. Carriers literally carry toner to the surface of the photoreceptor and are frequently made of materials based on special grades of sand, glass, steel or ferrite types of substances. They may be coated with a small amount of polymer to achieve the desired behaviour in a specific application. Carrier/toner mixtures are known as two-component developers. Single-component developers do not use a separate carrier. Rather, they incorporate a compound like iron oxide into the toner and utilize a magnetic device for applying the developer to the photoreceptor.

Fuser lubricants are most often silicone-based fluids which are applied to fuser rolls to prevent toner offset from the developed image to the roll. While many are simple polydimethylsiloxanes (PDMSs), others contain a functional component to enhance their adhesion to the fuser roll. Some fuser lubricants are poured from a bottle into a sump, from which they are pumped and ultimately applied to the fuser roll. In other machines the lubricant may be applied via a saturated fabric web which wipes part of the roll’s surface, while in some smaller machines and printers, an oil-impregnated wick makes the application.

Most, if not all, modern photocopiers are made to perform well with various weights of ordinary, untreated bond paper. Special carbonless forms are made for some high-speed machines, and non-fusing transfer papers are produced for imaging in photocopiers and then applying the image to a T-shirt or other fabric with the application of heat and pressure in a press. Large engineering/architectural drawing copiers often produce their copies on a translucent velum.

Potential hazards and their prevention

Responsible manufacturers have worked hard to minimize the risk from any unique hazards in the photocopying process. However, material safety data sheets (MSDSs) should be obtained for any consumables or service chemicals used with a particular machine.

Perhaps the only unique material to which one may be significantly exposed in the photocopying process is toner. Modern, dry toners should not present a skin or eye hazard to any but perhaps the most sensitive individuals, and recently designed equipment utilizes toner cartridges and CRUs that minimize contact with bulk toner. Liquid toners, as well, should not be directly irritating to the skin. However, their isoparaffinic hydrocarbon carriers are solvents and can defat the skin, leading to dryness and cracking upon repeated exposure. These solvents may also be mildly irritating to the eyes.

Well-designed equipment will not present a bright light hazard, even if the platen is flashed with no original on it, and some illumination systems are interlocked with the platen cover to prevent any operator exposure to the light source. All laser printers are classified as Class I laser products, meaning that, under normal conditions of operation, the laser radiation (beam) is inaccessible, being contained within the printing process, and does not present a biological hazard. Additionally, the laser device should not require maintenance, and in the highly unusual event that access to the beam is required, the manufacturer must provide safe working procedures to be followed by a properly trained service technician.

Finally, properly manufactured hardware will not have sharp edges, pinch points or exposed shock hazards in areas where operators might place their hands.

Skin and eye hazards

In addition to dry toners not presenting a significant skin or eye hazard, one would expect the same with silicon oil-based fuser lubricants. Polydimethylsiloxanes (PDMSs) have been subjected to extensive toxicological evaluations and have generally been found to be benign. While some low-viscosity PDMSs may be eye irritants, those used as fuser lubricants usually are not, nor are they skin irritants. Regardless of actual irritation, any of these materials will be nuisances either on the skin or in the eyes. Affected skin may be washed with soap and water, and eyes should be flooded with water for several minutes.

Individuals frequently working with liquid toners, especially under potential splash conditions, may want to wear protective goggles, safety glasses with side shields, or a face shield if needed. Rubber or vinyl-coated gloves should prevent the dry skin problems mentioned above.

Papers are generally benign as well. However, there have been cases of significant skin irritation when proper care was not taken during processing. Poor manufacturing processes can also cause odour problems when the paper is heated in the fuser of a dry-process copier. Occasionally, the vellum in an engineering copier has not been properly processed and creates a hydrocarbon solvent odour problem.

In addition to the isoparaffinic base of liquid toners, numerous solvents are routinely used in machine upkeep. Included are platen and cover cleaners and film removers, which, typically, are alcohols or alcohol/water solutions containing small amounts of surfactants. Such solutions are eye irritants, but do not directly irritate the skin. However, like the liquid toner dispersants, their solvent action can defat skin and lead to eventual skin-cracking problems. Rubber or vinyl-coated gloves and goggles or safety glasses with side shields should be sufficient to preclude problems.

Inhalation hazards

Ozone is usually the greatest concern of those in the general vicinity of photocopiers. The next most readily identified concerns would be toner, including paper dust, and volatile organic compounds (VOCs). Some situations also give rise to odour complaints.

Ozone is primarily generated by corona discharge from the devices (corotrons/scorotrons) which charge the photoreceptor in preparation for exposure and cleaning. At concentrations most apt to be encountered in photocopying, it can be identified by its pleasant, clover-like odour. Its low odour threshold (0.0076 to 0.036 ppm) gives it good “warning properties”, in that its presence can be detected before it reaches harmful concentrations. As it reaches concentrations which might produce headaches, eye irritation and breathing difficulty, its odour becomes strong and pungent. One should not expect ozone problems from well-maintained machines in properly ventilated areas. However, ozone may be detected when operators work in the machine’s exhaust stream, especially in the case of long copy runs. Odours that are identified as ozone by inexperienced operators are usually found to have arisen from other sources.

Toner has long been considered to be a nuisance particulate, or “particulate not otherwise classified” (PNOC). Studies performed by Xerox Corporation in the 1980s indicated that inhaled toner elicits the pulmonary responses one would expect from exposure to such insoluble particulate materials. They also demonstrated a lack of carcinogenic hazard at exposure concentrations well above those expected to be found in the office environment.

Paper dust consists of paper fibre fragments and sizers and fillers such as clay, titanium dioxide and calcium carbonate. All of these materials are considered to be PNOCs. No reasons for concern have been found for the paper dust exposures expected to occur in the office environment.

The emission of VOCs by photocopiers is a byproduct of their use in plastic toners and parts, rubbers and organic lubricants. Even so, exposures to individual organic chemicals in the environment of an operating photocopier are usually orders of magnitude below any occupational exposure limits.

Odour problems with modern photocopiers are most often an indication of inadequate ventilation. Treated papers, such as carbonless forms or image transfer papers, and occasionally vellums used in engineering copiers, may produce hydrocarbon solvent odours, but exposures will be well below any occupational exposure limits if ventilation is adequate for normal copying. Modern photocopiers are complex electro-mechanical devices which have some parts (fusers) operating at elevated temperatures. In addition to odours that are present during normal operation, odours also occur when a part fails under a heat load and the smoke and emissions from hot plastic and/or rubber are released. Obviously, one should not remain in the presence of such exposures. Common to nearly all odour problems are complaints of nausea and some sort of eye or mucous membrane irritation. These complaints are usually simply indications of exposure to an unknown, and probably unpleasant, odour, and are not necessarily signs of significant acute toxicity. In such cases, the exposed individual should seek fresh air, which nearly always leads to a rapid recovery. Even exposures to smoke and vapours from overheated parts are usually of such short duration that there is no need for concern. Even so, it is only prudent to seek medical advice if symptoms persist or exacerbate.

Installation considerations

As discussed above, copiers produce heat, ozone and VOCs. While the siting and ventilation recommendations should be obtained from the manufacturer and should be followed, it is reasonable to expect that, for all but possibly the largest machines, location in a room having reasonable air circulation, more than two air changes per hour and adequate space around the machine for servicing will be sufficient to prevent ozone and odour issues. Naturally, this recommendation also assumes that all American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) recommendations for room occupants are also met. If more than one photocopier is added to a room, care should be taken to provide added ventilation and cooling capability. Large, high-volume machines may require special heat-control considerations.

Supplies do not require special considerations beyond those for the keeping of any flammable solvents and avoiding excessive heat. Paper should be kept in its box to the extent practical and the wrapper should not be opened until the paper is needed.

Facsimile (Fax) Machines

Processing operations.

In facsimile reproduction, the document is scanned by a light source and the image is converted to an electronic form compatible with telephone communications. At the receiver, electro-optical systems decode and print the transmitted image via direct thermal, thermal transfer, xerographic or ink-jet processes.

Machines using the thermal processes have a linear print array like a printed circuit board, over which the copy paper is stepped during the printing process. There are about 200 contacts per inch across the width of the paper, which are rapidly heated when activated by an electric current. When hot, a contact either causes the contact spot on a treated copy paper to turn black (direct thermal) or the coating on a typewriter ribbon-like donor roll to deposit a black dot onto the copy paper (thermal transfer).

Fax machines which operate by the xerographic process use the telephone-transmitted signal to activate a laser beam and they then function the same as a laser printer. In a similar fashion, ink-jet machines function the same as ink-jet printers.

Materials.

Paper, either treated or plain, donor rolls, toner and ink are the major materials used in faxing. Direct thermal papers are treated with leuco dyes, which turn from white to black when heated. Donor rolls contain a mixture of carbon black in a wax and polymer base, coated onto a film substrate. The mixture is sufficiently firm that it does not transfer to the skin when rubbed, but when heated it will transfer to the copy paper. Toners and inks are discussed in the photocopying and ink-jet printing sections.

Potential hazards and their prevention.

No unique hazards have been associated with fax machines. There have been odour complaints with some early direct thermal machines; however, as with many odours in the office environment, the problem is more indicative of a low odour threshold, and possibly inadequate ventilation, than a health problem. Thermal transfer machines usually are odour free, and no hazards have been identified with the donor rolls. Xerographic fax machines have the same potential problems as dry photocopiers; however, their low speed normally precludes any inhalation concerns.

Blueprinting (Diazo)

Processing operations.

Modern references to “blueprints” or “blueprint machines” generally mean diazo copies or copiers. These copiers are most often used with large architectural or engineering drawings made on a film, vellum or translucent paper base. Diazo-treated papers are acidic and contain a coupler which yields a colour change upon reaction with the diazo compound; however, the reaction is prevented by the acidity of the paper. The sheet to be copied is placed in contact with the treated paper and exposed to intense ultraviolet (UV) light from a fluorescent or mercury vapour source. The UV light breaks the diazo bond on the areas of the copy paper not protected from exposure by the image on the master, eliminating the possibility of subsequent reaction with the coupler. The master is then removed from contact with the treated paper, which is then exposed to an ammonia atmosphere. The alkalinity of the ammonia developer neutralizes the acidity of the paper, permitting the diazo/coupler colour-change reaction to produce a copy of the image on the parts of the paper which were protected from the UV by the image on the master.

Materials.

Water and ammonia are the only diazo-process materials in addition to the treated paper.

Potential hazards and their prevention.

The obvious concern around diazo-process copiers is the exposure to ammonia, which can cause eye and mucous membrane irritation. Modern machines usually control emissions, and hence exposures are usually considerably less than 10 ppm. However, older equipment may require careful and frequent maintenance and possible local exhaust ventilation. Care should be taken when servicing a machine to avoid spills and prevent eye contact. Manufacturers’ recommendations regarding protective equipment should be followed. One should also be aware that improperly manufactured paper also has the potential for causing skin problems.

Digital Duplicators and Mimeographs

Processing operations.

Digital duplicators and mimeographs share the same basic process in that a master stencil is “burned” or “cut” and placed onto an ink-containing drum, from which ink flows through the master onto the copy paper.

Materials.

Stencils, inks and papers are the supplies used by these machines. The scanned image is digitally burned onto the mylar master of a digital duplicator, while it is electro-cut into a mimeograph’s paper stencil. A further difference is that digital duplicator inks are water based, though containing some petroleum solvent, while mimeograph inks are based on either a naphthenic distillate or a glycol ether/alcohol mixture.

Potential hazards and their prevention.

The primary hazards associated with digital duplicators and mimeographs are due to their inks, although there is a potential hot wax vapour exposure associated with burning the image onto the digital duplicator’s stencil and an ozone exposure during the electro-cutting of stencils. Both types of ink have the potential for eye and skin irritation, while mimeograph ink’s higher petroleum distillate content has a greater potential for causing dermatitis. The use of protective gloves while working with the inks, and adequate ventilation while making copies, should protect against skin and inhalation hazards.

Spirit Duplicators

Processing operations.

Spirit duplicators use a reverse-image stencil which is coated with an alcohol-soluble dye. In processing, the copy paper is lightly coated with a methanol-based duplicating fluid, which removes a small amount of dye upon coming in contact with the stencil, resulting in image transfer to the copy paper. The copies may emit methanol for some time after duplication.

Materials.

Paper, stencils and duplicating fluid are the main supplies for this equipment.

Potential hazards and their prevention.

Spirit duplicating fluids are usually methanol based, and hence are toxic if absorbed through the skin, inhaled or ingested; they are also flammable. Ventilation should be adequate to ensure operator exposures are below current occupational exposure limits and should include providing a ventilated area for drying. Some more recent duplicating fluids used are ethyl alcohol or propylene glycol based, which avoid the toxicity and flammability concerns of methanol. Manufacturers’ recommendations should be followed regarding the use of protective equipment when handling all duplicating fluids.

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Interpreting the human health data in the printing, commercial photographic processing and reproduction industry is no simple matter, since the processes are complex and are continually evolving - sometimes dramatically. While the use of automation has substantially reduced manual work exposures in modernized versions of all three of the disciplines, work volume per employee has increased substantially. Furthermore, dermal exposure represents an important route of exposure for these industries, yet is less well characterized by available industrial hygiene data. Case reporting of the less serious, reversible effects (e.g., headaches, nose and eye irritation) is incomplete and under-reported in the published literature. Despite these challenges and limitations, epidemiological studies, health surveys and case reports provide a substantial amount of information regarding the health status of workers in these industries.

Printing Activities

Agents and exposures

Today there are five categories of printing processes: flexography, gravure, letterpress, lithography and screen printing. The type of exposure that can occur from each process is related to the types of printing inks that are used and to the likelihood of inhalation (mists, solvent fumes and so on) and penetrable skin contact from the process and cleaning activities employed. It should be noted that the inks are composed of organic or inorganic pigments, oil or solvent vehicles (i.e., carriers), and additives applied for special printing purposes. Table 1 outlines some characteristics of different printing processes.

Table 1. Some potential exposures in the printing industry

Mortality and chronic risks

Several epidemiological and case-report studies exist on printers. Exposure characterizations are not quantified in much of the older literature. However, respirable-size carbon black particles with potentially carcinogenic polycyclic aromatic hydrocarbons (benzo(a)pyrene) bound to the surface have been reported in rotary letterpress printing machine rooms of newspaper production. Animal studies find the benzo(a)pyrene tightly bound to the surface of the carbon black particle and not easily released to lung or other tissues. This lack of “bioavailability” makes it more difficult to determine whether cancer risks are feasible. Several, but not all, cohort (i.e., populations followed through time) epidemiological studies have found suggestions of increased lung cancer rates in printers (table 2). A more detailed assessment of over 100 lung cancer cases and 300 controls (case-control type study) from a group of over 9,000 printing workers in Manchester, England (Leon, Thomas and Hutchings 1994) found that the duration of work in a machine room was related to lung cancer occurrence in rotary letterpress workers. Since smoking patterns of the workers are not known, direct consideration of the role of occupation in the study is unknown. However, it is suggestive that rotary letterpress work may have presented a lung cancer risk in previous decades. In some areas of the world, however, older technologies, such as rotary letterpress work, may still exist and thus afford opportunities for preventive assessments, as well as installation of appropriate controls where needed.

* Standardized Mortality Ratios (SMR) = number of observed deaths divided by number of expected deaths, adjusted for age effects over the time periods in question. An SMR of 1 indicates no difference between observed and expected. Note: 95% confidence intervals are provided for the SMRs.

NGA = National Graphical Association, UK

NATSOPA = National Society of Operative Printers, Graphical and Media Personnel, UK.

Sources: Paganini-Hill et al. 1980; Bertazzi and Zoccheti 1980; Michaels, Zoloth and Stern 1991; Leon 1994; Svensson et al. 1990; Sinks et al. 1992.

Another group of workers that has been substantially studied are lithographers. Modern lithographers’ exposure to organic solvents (turpentine, toluene and so on), pigments, dyes, hydroquinone, chromates and cyanates has been markedly reduced in recent decades due to the use of computer technologies, automated processes and changes in materials. The International Agency for Research on Cancer (IARC) recently concluded that occupational exposures in printing process are possibly carcinogenic to humans (IARC 1996). At the same time, it may be important to point out that IARC’s conclusion is based on historical exposures which, in most cases, should be significantly different today. Reports of malignant melanoma have suggested risks about twice the expected rate (Dubrow 1986). While some postulate that skin contact with hydroquinone could be related to melanoma (Nielson, Henriksen and Olsen 1996), it has not been confirmed in a hydroquinone manufacturing plant where significant exposure to hydroquinone was reported (Pifer et al. 1995). However, practices which minimize skin contact with solvents, particularly in plate cleaning, should be emphasized.

Photographic Processing Activities

Exposures and agents

Photographic processing of black-and-white or colour film or paper can be done either manually or by essentially fully automated larger-scale processes. The selection of the process, chemicals, working conditions (including ventilation, hygiene and personal protective equipment) and workload can all influence the types of exposures and potential health issues of the occupational environment. The types of jobs (i.e., processor-related tasks) having the greatest potential for exposure to key photographic chemicals, such as formaldehyde, ammonia, hydroquinone, acetic acid and colour developers, are noted in table 3. The typical photographic processing and handling work flow is depicted in figure 1.

Table 3. Tasks in photographic processing with chemical exposure potential

Figure 1. Photographic processing operations

In more recently designed high-volume processing units, some of the steps in the workflow have been combined and automated, making inhalation and skin contact less likely. Formaldehyde, an agent that has been used for decades as a colour image stabilizer, is diminishing in concentration in photographic product. Depending on the specific process and site environmental conditions, its air concentration may range from non-detectable levels in the operator’s breathing zone up to about 0.2 ppm at machine dryer vents. Exposures can also occur during equipment cleaning, making or replenishing stabilizer fluid and unloading processors, as well as in spill situations.

It should be noted that while chemical exposures have been the primary focus of most health studies of photographic processors, other work environmental aspects, such as reduced light, materials handling and the postural demands of the job, are also of preventive health interest.

Mortality risks

The only published mortality surveillance of photographic processors suggests no increased risks of death for the occupation (Friedlander, Hearne and Newman 1982). The study covered nine processing laboratories in the United States, and was updated to cover 15 more years of follow-up (Pifer 1995). It should be noted that this is a study of over 2,000 employees who were actively working at the beginning of 1964, with over 70% of them having had at least 15 years of employment in their profession at that time. The group was followed for 31 years, through 1994. Many exposures relevant earlier in the careers of these employees, such as carbon tetrachloride, n-butylamine, and isopropylamine, were discontinued in the laboratories over thirty years ago. However, many of the key exposures in modern laboratories (i.e., acetic acid, formaldehyde and sulphur dioxide) were also present in previous decades, albeit at much higher concentrations. During the 31-year follow-up time period, the standardized mortality ratio was only 78% of that expected (SMR 0.78), with 677 deaths in the 2,061 workers. No individual causes of death were significantly increased.

The 464 processors in the study also had reduced mortality, whether compared to the general population (SMR 0.73) or to other hourly workers (SMR 0.83) and had no significant increases in any cause of death. Based on available epidemiological information, it does not appear that photographic processing presents an increased mortality risk, even at the higher concentrations of exposure likely to have been present in the 1950s and 1960s.

Pulmonary disease

The literature has very few reports of pulmonary disorders for photographic processors. Two articles, (Kipen and Lerman 1986; Hodgson and Parkinson 1986) describe a total of four potential pulmonary responses to processing workplace exposures; however, neither had quantitative environmental exposure data to assess the measured pulmonary findings. No increases in longer-term illness absence for pulmonary disorders was identified in the only epidemiological review of the subject (Friedlander, Hearne and Newman 1982); however, it is important to note that illness-absences of eight consecutive days were required in order to be captured in that study. It appears that respiratory symptoms can be aggravated or initiated in sensitive individuals by exposure to higher concentrations of acetic acid, sulphur dioxide and other agents in photographic processing, should ventilation be poorly controlled or errors occur during mixing, resulting in the release of undesired concentrations of these agents. However, work-related pulmonary cases have only rarely been reported in this occupation (Hodgson and Parkinson 1986).

Acute and subchronic effects

Contact irritative and allergic dermatitis has been reported in photographic processors for decades, starting with the initial use of colour chemicals in the late 1930s. Many of these cases occurred in the first few months of a processor’s exposure. The use of protective gloves and improved handling processes have substantially reduced photographic dermatitis. Eyesplashes with some photochemicals can present risks of corneal injury. Training on eyewash procedures (flushing eyes with cool water for at least 15 minutes followed by medical attention) and the use of protective eyewear is particularly important for photoprocessors, many of whom may work in isolation and/or in diminished light environments.

Some ergonomics concerns exist regarding the operation of rapid-turnaround, high-volume photographic processing units. The mounting and dismounting of large rolls of photographic paper can present a risk of upper back, shoulder and neck disorders. The rolls can weigh 13.6 to 22.7 kg (30 to 50 pounds), and may be awkward to handle, depending partly on access to the machine, which can be compromised in compact work sites.

Injuries and strains to the staff can be prevented by proper staff training, by provision of adequate access to the rolls and by considerations of human factors in the general design of the processing area.

Prevention and methods of early detection of effects

Protection from dermatitis, respiratory irritation, acute injury and ergonomic disorders starts with the recognition that such disorders can occur. With proper worker information (including labels, material safety data sheets, protective equipment and health protection training programmes), periodic health/safety reviews of the worksetting and informed supervision, prevention can be strongly emphasized. In addition, the early identification of disorders can be facilitated by having a medical resource for worker health reporting, coupled with targeted voluntary periodic health assessments, focusing on respiratory and upper extremity symptoms in questionnaires and direct observation of exposed skin areas for signs of work-related dermatitis.

Because formaldehyde is a potential respiratory sensitizer, a strong irritant and a possible carcinogen, it is important that each workplace be assessed to determine where formaldehyde is used (chemical inventory and material safety data sheet reviews), to assess air concentrations (if indicated by materials used), to identify where leaks or spills could occur and to estimate the quantity that could be spilled and the concentration generated in worst-case scenarios. An emergency response plan should be developed, conspicuously posted, communicated and periodically practised. A health and safety specialist should be consulted in the development of such an emergency plan.

Reproduction Activities

Agents and exposures

Modern photocopying machines emit very low levels of ultraviolet radiation through the glass cover (plenum), generate some noise and may emit low concentrations of ozone during the processing activity. These machines use a toner, primarily carbon black (for black-and-white printers), to produce a dark print on the paper or transparent film. Thus, potential routine exposures of health interest for photocopy operators can include ultraviolet radiation, noise, ozone and possibly toner. In older machines, toner could be an issue during replacement, although modern self-contained cartridges have substantially reduced potential respiratory and skin exposure.

The degree of ultraviolet radiation exposure that occurs through the copier machine platen glass is very low. The duration of a photocopier flash is approximately 250 microseconds, with continual copying making about 4,200 flashes per hour - a value that can vary depending upon the copier. With the glass platen in place, the emitted wavelength ranges from 380 to about 396 nm. UVB does not typically result from copier flashes. UVA measurements maximally recorded at the glass paten average about 1.65 microjoule/cm² per flash. Thus, the maximum 8-hour near-UV spectral exposure from a continuously run photocopier making about 33,000 copies per day is approximately 0.05 joules/cm² at the glass surface. This value is only a fraction of the threshold limit value recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) and appears to present no measurable health risk, even in such exaggerated exposure conditions.

It should be noted that certain workers may be at higher risk for UV exposures, including those with photosensitive conditions, people using photosensitizing agents/medicines and people with impaired ocular pupils (aphakics). Such people are usually advised to minimize their UV exposures as a general precautionary measure.

Acute effects.

The literature does not reveal many acute effects meaningfully related to photocopying. Older, insufficiently maintained units could emit detectable ozone concentrations if run in poorly vented settings. While eye and upper respiratory irritation symptoms have been reported from workers in such environments, the minimum manufacturer specifications for space and ventilation, coupled with newer copier technology, have essentially eliminated ozone as an emission issue.

Mortality risks.

No studies were found that described mortality or chronic health risks from long-term photocopying.

Prevention and early detection

By simply following manufacturers’ recommended use, photocopying activity should not present a workplace risk. Individuals experiencing an aggravation of symptoms related to intense use of photocopiers should seek health and safety advice.

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Major Environmental Issues

Solvents

Organic solvents are used for a number of applications in the printing industry. Major uses include cleaning solvents for presses and other equipment, solubilizing agents in inks, and additives in fountain solutions. In addition to general concerns about volatile organic compound (VOC) emissions, some potential solvent components may be persistent in the environment or have high ozone-depleting potential.

Silver

During black-and-white and colour photographic processing, silver is released into some of the processing solutions. It is important to understand the environmental toxicology of silver so that these solutions can be properly handled and disposed of. While free silver ion is highly toxic to aquatic life, its toxicity is much lower in a complexed form as in photoprocessing effluent. Silver chloride, silver thiosulphate and silver sulphide, which are forms of silver commonly observed in photoprocessing, are over four orders of magnitude less toxic than silver nitrate. Silver has a high affinity for organic material, mud, clay and other matter found in natural environments, and this lessens its potential impact in aquatic systems. Given the extremely low level of free silver ion found in photoprocessing effluents or in natural waters, control technology appropriate to complexed silver is sufficiently protective of the environment.

Other photoprocessing effluent characteristics

The composition of photographic effluent varies, depending on the processes being run: black-and-white, colour reversal, colour negative/positive or some combination of these. Water comprises 90 to 99% of the effluent volume, with the majority of the remainder being inorganic salts that function as buffers and fixing (silver halide-solubilizing) agents, iron chelates, such as FeEthylene diamine tetra-acetic acid, and organic molecules that serve as developing agents and anti-oxidants. Iron and silver are the significant metals present.

Solid waste

Every component of the printing, photography and reproduction industries generates solid waste. This can consist of packaging waste such as cardboard and plastics, consumables such as toner cartridges or waste material from operations such as scrap paper or film. Increasing pressure on industrial generators of solid waste has led businesses to examine carefully options to lower solid waste through reduction, reuse or recycling.

Equipment

Equipment plays an obvious role in determining the environmental impact of the processes used in the printing, photography and reproduction industries. Beyond this, scrutiny is increasing on other aspects of equipment. One example is energy efficiency, which relates back to the environmental impact of the energy generation. Another example is “takeback legislation”, which requires the manufacturers to receive equipment back for proper disposal after its useful commercial life.

Control Technologies

The effectiveness of a given control methodology can be quite dependent on the specific operating processes of a facility, the size of that facility and the necessary level of control.

Solvent control technologies

Solvent use can be reduced in several ways. More volatile components, such as isopropyl alcohol, can be replaced with compounds having lower vapour pressure. In some situations, solvent-based inks and washes can be replaced with water-based materials. Many printing applications need improvements in water-based options to compete effectively with solvent-based materials. High-solids ink technology can also result in reduction of organic solvent use.

Solvent emissions can be lowered by reducing the temperature of dampening or fountain solutions. In limited applications, solvents can be captured on adsorptive materials such as activated carbon, and reused. In other instances, windows of operation are too strict to allow captured solvents to be reused directly, but they may be recaptured for recycling offsite. Solvent emissions may be concentrated in condenser systems. These systems consist of heat exchangers followed by a filter or electrostatic precipitator. The condensate passes through an oil-water separator before ultimate disposal.

In larger operations, incinerators (sometimes called afterburners) can be used to destroy emitted solvents. Platinum or other precious metal materials may be used to catalyze the thermal process. Non-catalyzed systems must operate at higher temperatures but are not sensitive to processes that can poison catalysts. Heat recovery is generally necessary to make non-catalyzed systems cost effective.

Silver recovery technologies

The level of silver recovery from photoeffluent is controlled by the economics of recovery and/or by solution discharge regulations. Major silver recovery techniques include electrolysis, precipitation, metallic replacement and ion exchange.

In electrolytic recovery, current is passed through the silver-bearing solution and silver metal is plated on the cathode, usually a stainless steel plate. The silver flake is harvested by flexing, chipping or scraping and sent to a refiner for reuse. Attempting to lower the residual solution silver level significantly below 200 mg/l is inefficient and can result in formation of undesired silver sulphide or noxious sulphurous byproducts. Packed-bed cells are capable of reducing silver to lower levels but are more complex and expensive than cells with two-dimensional electrodes.

Silver may be recovered from solution by precipitation with some material that forms an insoluble silver salt. The most common precipitating agents are trisodium trimercaptotriazine (TMT) and various sulphide salts. If a sulphide salt is used, care must be taken to avoid generation of highly toxic hydrogen sulphide. TMT is an inherently safer alternative recently introduced to the photoprocessing industry. Precipitation has a recovery efficiency of greater than 99%.

Metallic replacement cartridges (MRCs) allow the flow of the silver-bearing solution over a filamentous deposit of iron metal. Silver ion is reduced to silver metal as iron is oxidized to ionic soluble species. The metallic silver sludge settles to the bottom of the cartridge. MRCs are not appropriate in areas where iron in the effluent is a concern. This method has a recovery efficiency of greater than 95%.

In ion exchange, anionic silver thiosulphate complexes exchange with other anions on a resin bed. When the capacity of the resin bed is exhausted, additional capacity is regenerated by stripping the silver with a concentrated thiosulphate solution or converting the silver to silver sulphide under acidic conditions. Under well-controlled conditions, this technique can lower silver below 1 mg/l. However, ion-exchange can be used only on solutions dilute in silver and thiosulphate. The column is extremely sensitive to stripping if the thiosulphate concentration of the influent is too high. Also, the technique is very labour- and equipment-intensive, making it expensive in practice.

Other photoeffluent control technologies

The most cost-efficient method to handle photographic effluent is via biological treatment at a secondary waste treatment plant (often referred to as a publicly owned treatment works, or POTW). Several constituents or parameters of photographic effluent may be regulated by sewer discharge permits. In addition to silver, other common regulated parameters include pH, chemical oxygen demand, biological oxygen demand and total dissolved solids. Multiple studies have demonstrated that photoprocessing wastes (including the small amount of silver remaining after reasonable silver recovery) following biological treatment are not expected to have an adverse effect on the receiving waters.

Other technologies have been applied to photoprocessing wastes. Haul-away for treatment in incinerators, cement kilns or other ultimate disposal is practised in some regions of the world. Some laboratories reduce the volume of solution to be hauled away through evaporation or distillation. Other oxidative techniques such as ozonation, electrolysis, chemical oxidation and wet air oxidation have been applied to photoprocessing effluents.

Another major source of reduced environmental burden is through source reduction. The level of silver coated per square metre in sensitized goods is steadily decreasing as new generations of products enter the marketplace. As the silver levels in media decrease, the amount of chemicals necessary to process a given area of film or paper has also decreased. Regeneration and reuse of solution overflows have also resulted in less environmental burden per image. For example, the amount of colour developing agent required to process a square metre of colour paper in 1996 is less than 20% of that required in 1980.

Solid-waste minimization

The desire to minimize solid waste is encouraging efforts to recycle and reuse materials rather than dispose of them in landfills. Recycling programmes exist for toner cartridges, film cassettes, single-use cameras and so on. Recycling and reuse of packaging is becoming more prevalent as well. More packaging and equipment parts are being labelled appropriately to allow more efficient material recycling programmes.

Life cycle analysis design for the environment

All of the issues discussed above have resulted in increasing consideration of the entire life cycle of a product, from procuring of natural resources to creating the products, to dealing with end-of-life issues for these products. Two related analytic tools, life cycle analysis and design for the environment, are being used to incorporate environmental issues into the decision-making process in product design, development and sales. Life cycle analysis takes into consideration all of the inputs and material flows for a product or process and attempts to quantitatively measure the impact on the environment of different options. Design for the environment brings into consideration various aspects of product design such as recyclability, reworkability and so on to minimize the impact on the environment of the production or disposal of the equipment in question.

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Materials and Processing Operations

Black-and-white processing

In black-and-white photographic processing, exposed film or paper is removed from a light-tight container in a darkroom and sequentially immersed in water solutions of developer, stop bath and fixer. After a water washing, the film or paper is dried and ready for use. The developer reduces the light-exposed silver halide to metallic silver. The stop bath is a weakly acidic solution that neutralizes the alkaline developer and stops further reduction of the silver halide. The fixer solution forms a soluble complex with the unexposed silver halide, which is subsequently removed from the emulsion in the washing process together with various water-soluble salts, buffers and halide ions.

Colour processing

Colour processing is more complex than black-and-white processing, with additional steps required for processing most types of colour film, transparencies and paper. In short, instead of one silver halide layer, as in black-and-white films, there are three superimposed silver negatives; that is, a silver negative is produced for each of three sensitized layers. On contact with the colour developer, the exposed silver halide is converted to metallic silver while the oxidized developer reacts with a specific coupler in each layer to form the dye image.

Another difference in colour processing is the use of a bleach to remove the unwanted metallic silver from the emulsion by converting metallic silver to silver halide by means of an oxidizing agent. Subsequently, the silver halide is converted to a soluble silver complex, which is then removed by washing as in the case of black-and-white processing. In addition, colour processing procedures and materials vary depending on whether a colour transparency is being formed or whether colour negatives and colour prints are being processed.

General processing design

The essential steps in photoprocessing thus consist of passing the exposed film or paper through a series of processing tanks either by hand or in machine processors. Although the individual processes may be different, there are similarities in the types of procedures and equipment used in photoprocessing. For example, there will be a storage area for chemicals and raw materials and facilities for handling and sorting incoming exposed photographic materials. Facilities and equipment are necessary for measuring, weighing and mixing processing chemicals, and for supplying these solutions to the various processing tanks. In addition, a variety of pumping and metering devices are used to deliver processing solutions to tanks. A professional or photofinishing laboratory will typically utilize larger, more automated equipment that will process either film or paper. To produce a consistent product, the processors are temperature controlled and, in most cases, are replenished with fresh chemicals as sensitized product is run through the processor.

Larger operations may have quality-control laboratories for chemical determinations and measurement of photographic quality of materials being produced. Although the use of packaged chemical formulations may eliminate the need for measuring, weighing and maintaining a quality-control laboratory, many large photoprocessing facilities prefer to mix their own processing solutions from bulk quantities of the constituent chemicals.

Following the processing and drying of materials, protective lacquers or coatings may be applied to the finished product, and film-cleaning operations may take place. Finally, materials are inspected, packaged and prepared for shipment to the customer.

Potential Hazards and their Prevention

Unique darkroom hazards

The potential hazards in commercial photographic processing are similar to those in other types of chemical operations; however, a unique feature is the requirement that certain portions of the processing operations be conducted in darkness. Consequently, the processing operator must have a good understanding of the equipment and its potential hazards, and of precautionary measures in case of accidents. Safelights or infrared goggles are available and can be used to provide sufficient illumination for operator safety. All mechanical elements and live electrical parts must be enclosed and projecting machine parts must be covered. Safety locks should be installed to ensure that light does not enter the darkroom and should be designed so that they allow free passage of personnel.

Skin and eye hazards

Because of the wide variety of formulae used by various suppliers and different methods of packaging and mixing photoprocessing chemicals, only a few generalizations can be made regarding the types of chemical hazards present. A variety of strong acids and caustic materials may be encountered, especially in storage and mixing areas. Many photoprocessing chemicals are skin and eye irritants and, in some cases, may cause skin or eye burns following direct contact. The most frequent health issue in photoprocessing is the potential for contact dermatitis, which most commonly arises from skin contact with alkaline developer solutions. The dermatitis may be due to irritation caused by alkaline or acidic solutions, or, in some cases, to skin allergy.

Colour developers are aqueous solutions that usually contain derivatives of p-phenylenediamine, whereas black-and-white developers usually contain p-methyl-aminophenolsulphate (also known as Metol or KODAK ELON Developing Agent) and/or hydroquinone. Colour developers are more potent skin sensitizers and irritants than black-and-white developers and may also cause lichenoid reactions. In addition, other skin sensitizers such as formaldehyde, hydroxylamine sulphate and S-(2-(dimethylamino)-ethyl)-isothiouronium dihydrochloride are found in some photoprocessing solutions. The development of skin allergy is more likely to occur after repeated and prolonged contact with processing solutions. Persons with pre-existing skin diseases or skin irritation are often more susceptible to the effects of chemicals on the skin.

Avoiding skin contact is an important goal in photoprocessing areas. Neoprene gloves are recommended for reducing skin contact, especially in the mixing areas, where more concentrated solutions are encountered. Alternatively, nitrile gloves may be used when prolonged contact with photochemicals is not required. Gloves should be of sufficient thickness to prevent tears and leaks, and should be inspected and cleaned frequently, preferably by thorough washing of the outer and inner surfaces with a non-alkaline hand cleaner. It is particularly important that maintenance personnel be provided with protective gloves during repair or cleaning of the tanks and rack assemblies, and so on, since these may become coated with deposits of chemicals. Barrier creams are not appropriate for use with photochemicals because they are not impervious to all photochemicals and may contaminate processing solutions. A protective apron or lab coat should be worn in the darkroom, and frequent laundering of work clothing is desirable. For all reusable protective clothing, users should look for signs of permeation or degradation after each use and replace clothing as appropriate. Protective goggles and a face shield also should be used, especially in areas where concentrated photochemicals are handled.

If photoprocessing chemicals contact the skin, the affected area should be flushed quickly with copious amounts of water. Because materials such as developers are alkaline, washing with a non-alkaline hand cleaner (pH of 5.0 to 5.5) reduces the potential to develop dermatitis. Clothing should be changed immediately if there is any contamination with chemicals, and spills or splashes should be immediately cleaned up. Hand-washing facilities and provisions for rinsing the eyes are particularly important in the mixing and processing areas. Emergency shower facilities should also be available.

Inhalation hazards

In addition to potential skin and eye hazards, gases or vapours emitted from some photoprocessing solutions may present an inhalation hazard, as well as contribute to unpleasant odours, especially in poorly ventilated areas. Some colour processing solutions may release vapours such as acetic acid, triethanolamine and benzyl alcohol, or gases such as ammonia, formaldehyde and sulphur dioxide. These gases or vapours may be irritating to the respiratory tract and eyes, or, in some cases, may cause other health-related effects. The potential health-related effects of these gases or vapours is concentration dependent and is usually observed only at concentrations that exceed occupational exposure limits. However, because of a wide variation in individual susceptibility, some individuals—for example, persons with pre-existing medical conditions such as asthma—may experience effects at concentrations below occupational exposure limits.

Some photochemicals may be detectable by odour because of the chemical’s low odour threshold. Although the odour of a chemical is not necessarily indicative of a health hazard, strong odours or odours that are increasing in intensity may indicate that the ventilation system is inadequate and should be reviewed.

Appropriate photoprocessing ventilation incorporates both general dilution and local exhaust to exchange air at an acceptable rate per hour. Good ventilation offers the added benefit of making the working environment more comfortable. The amount of ventilation required varies according to room conditions, processing output, specific processors and processing chemicals. A ventilation engineer may be consulted to ensure optimum operation of room and local exhaust ventilation systems. High-temperature processing and nitrogen-burst agitation of tank solutions may increase the release of some chemicals to the ambient air. Processor speed, solution temperatures and solution agitation should be set at minimum suitable performance levels to reduce the potential release of gases or vapours from processing tanks.

General room ventilation—for example, 4.25 m³/min supply and 4.8 m³/min exhaust (equivalent to 10 air changes per hour in a 3 x 3 x 3-metre room), with a minimum outside air replenishment rate of 0.15 m³/min per m² floor area—is usually adequate for photographers who undertake basic photoprocessing. An exhaust rate higher than a supply rate produces a negative pressure in the room and reduces the opportunity for gases or vapours to escape to adjoining areas. The exhaust air should be discharged outside the building to avoid redistributing potential air contaminants within the building. If the processor tanks are enclosed and have an exhaust (see figure 1), the minimum air supply and exhaust rate can probably be reduced.

Figure 1. Enclosed-machine ventilation

Some operations (e.g., toning, film cleaning, mixing operations and special processing procedures) may require supplementary local exhaust ventilation or respiratory protection. Local exhaust is important because it reduces the concentration of airborne contaminants that might otherwise be recirculated by the general dilution ventilation system.

A lateral slot-type ventilation system for extracting vapours or gases at the surface of a tank may be used for some tanks. When designed and operated correctly, lateral slot-type exhausts draw clean air across the tank and remove contaminated air from the operator’s breathing zone and the surface of the processing tanks. Push-pull lateral slot-type exhausts are the most effective systems (see figure 2).

Figure 2. Open-tank with "push-pull" ventilation

A hooded or canopy exhaust system (see figure 3) is not recommended because operators often lean over tanks with their heads under the hood. In this position, the hood draws vapours or gases into the operator’s breathing zone.

Figure 3. Overhead canopy exhaust

Split-tank covers with local exhaust attached to the stationary portion on mixing tanks may be used to supplement general room ventilation in mixing areas. Tank covers (tight-fitting covers or floating lids) should be used to prevent the release of potential air contaminants from storage and other tanks. A flexible exhaust may be attached to tank covers to facilitate the removal of volatile chemicals (see figure 4). As appropriate, automixers, which allow individual parts of multicomponent products to be added directly to and subsequently mixed in processors, should be used because they decrease the potential for operator exposure to photochemicals.

Figure 4. Chemical mixing tank exhaust

When mixing dry chemicals, the containers should be emptied gently to minimize chemical dust from becoming airborne. Tables, benches, shelves and ledges should be wiped with a water-dampened cloth frequently to keep residual chemical dust from accumulating and later becoming airborne.

Facility and operations design

Surfaces that may be contaminated with chemicals should be constructed to permit flushing with water. Adequate provisions should be made for floor drains, particularly in storage, mixing and processing areas. Because of the potential for leaks or spills, arrangements should be made for containment, neutralization and proper disposal of photochemicals. Since floors may be wet at times, flooring around potentially wet areas should be covered with non-skid tape or paint for safety purposes. Consideration should also be given to potential electrical hazards. For electrical devices used in or near water, ground-fault circuit interrupters and appropriate grounding should be used.

As a general rule, photochemicals should be stored in a cool (at temperatures no lower than 4.4 °C), dry (relative humidity between 35 and 50%), well-ventilated area, where they can be easily inventoried and retrieved. Chemical inventories should be actively managed so that the quantities of hazardous chemicals stored can be minimized and so that materials are not stored beyond their expiration dates. All containers should be properly labelled.

Chemicals should be stored to minimize the likelihood of container breakage during storage and retrieval. Chemical containers should not be stored where they can fall over, above eye level or where personnel have to stretch to reach them. Most hazardous materials should be stored at a low level and on a firm base in order to avoid possible breakage and spilling on the skin or eyes. Chemicals that, if accidentally mixed, might lead to fire, explosion or toxic chemical release should be segregated. For example, strong acids, strong bases, reducers, oxidizers and organic chemicals should be stored separately.

Flammable and combustible liquids should be stored in approved containers and storage cabinets. Storage areas should be kept cool, and smoking, open flames, heaters or anything else that might cause accidental ignition should be prohibited. During transfer operations, it should be ensured that containers are properly bonded and grounded. The design and operation of storage and handling areas for flammable and combustible materials should comply with applicable fire and electrical codes.

Whenever possible, solvents and liquids should be dispensed by metering pumps rather than by pouring. Pipetting of concentrated solutions and establishing siphons by mouth should not be permitted. The use of pre-weighed or pre-measured preparations may simplify operations and reduce the opportunities for accidents. Careful maintenance of all pumps and lines is necessary to avoid leakage.

Good personal hygiene should always be practiced in photoprocessing areas. Chemicals should never be placed in beverage or food containers or vice versa; only containers intended for chemicals should be used. Food or drink should never be brought into areas where chemicals are used, and chemicals should not be stored in refrigerators used for food. After handling chemicals, hands should be washed thoroughly, especially before eating or drinking.

Training and education

All personnel, including maintenance and housekeeping, should be trained in safety procedures relevant to their job tasks. An education programme for all personnel is essential in promoting safe work practices and preventing accidents. The educational programme should be carried out before personnel are allowed to work, at regular intervals thereafter and whenever new potential hazards are introduced into the workplace.

Summary

The key to working safely with photoprocessing chemicals is to understand the potential hazards of exposure and to manage the risk to an acceptable level. Risk management strategies for controlling potential occupational hazards in photoprocessing should include:

• providing personnel with training on potential hazards and safety procedures in the workplace,

• encouraging personnel to read and understand hazard communication vehicles (e.g., safety data sheets and product labels),

• maintaining workplace cleanliness and good personal hygiene,

• making certain that processors and other equipment are installed, operated and maintained to manufacturers’ specifications,

• substituting with less hazardous or less odorous chemicals, where possible,

• using engineering controls (e.g., general and local exhaust ventilation systems) where applicable,

• using protective equipment (e.g., protective gloves, goggles or face shield) when necessary,

• establishing procedures to ensure prompt medical attention for anyone with evidence of injury, and

• consideration of environmental exposure monitoring and health monitoring of employees as a verification of effective risk management strategies.

Additional information on black-and-white processing is discussed in the Entertainment and the arts chapter.

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