This article is adapted from the 3rd edition “Encyclopaedia of Occupational Health” articles “Food industries”, by M Malagié; “Frozen food industry”, by G. Jenson; and “Canning and food preserving”, by J.C. Graham, which were revised by Donald L. Smith.

The term food industries covers a series of industrial activities directed at the processing, conversion, preparation, preservation and packaging of foodstuffs (see table 1). The raw materials used are generally of vegetable or animal origin and produced by agriculture, farming, breeding and fishing. This article provides an overview of the complex of food industries. Other articles in this chapter and Encyclopaedia deal with particular food industry sectors and particular hazards.

Table 1. The food industries, their raw materials and processes

The food industry today has become highly diversified, with manufacturing ranging from small, traditional, family-run activities that are highly labour intensive, to large, capital-intensive and highly mechanized industrial processes. Many food industries depend almost entirely on local agriculture or fishing. In the past, this meant seasonal production and hiring of seasonal workers. Improvements in food processing and preservation technologies have taken some of the pressure off workers to process food quickly to prevent spoilage. This has resulted in a decrease in seasonal employment fluctuations. However, certain industries still have seasonal activities, such as fresh fruit and vegetable processing and increases in production of baked goods, chocolate and so forth for holiday seasons. Seasonal workers are often women and foreign workers.

The world’s food product output has been increasing. World exports of food products in 1989 totalled US$290 billion, a 30% increase over 1981. Industrialized market economy countries had a 67% share of this export. Much of this increase can be attributed to an increased demand for processed food and drink, especially in developing countries where the market has not yet been saturated.

This increase in output of food and drink products, however, has not resulted in increased employment because of intensified competition, which has resulted in decreased employment in many food industries, especially in industrialized countries. This is due to increased productivity and mechanization in many of these industries.

Demographic pressure, uneven distribution of agricultural resources and the need to insure preservation of food products to facilitate their better distribution explain the rapid technical evolution in the food industries. Constant economic and marketing pressures drive the industry to provide new and different products for market, while other operations may make the same product in the same way for decades. Even highly industrialized facilities often resort to seemingly archaic techniques when starting new products or processes. In practice, to satisfy population requirements, there is a need not only for a sufficient quantity of foodstuffs, which presupposes an increase of production, but also strict control of sanitation to obtain the quality essential to maintain the health of the community. Only modernization of techniques justified by production volumes in a stable production environment will eliminate manual handling hazards. In spite of the extreme diversity of the food industries, the preparation processes can be divided into handling and storage of raw materials, extraction, processing, preservation and packaging.

Handling and Storage

Manipulation of the raw materials, the ingredients during processing and the finished products is varied and diverse. The current trend is to minimize manual handling by mechanization, through “continuous processing” and automation. Mechanical handling may involve: self-propelled in-plant transport with or without palletization or super or bulk sacks (often containing several thousand pounds of dry powder material); conveyor belts (e.g., with beets, grain and fruit); bucket elevators (e.g., with grain and fish); spiral conveyors (e.g., with confectionery and flour); air fluming (e.g., for unloading grain, sugar or nuts and for transport of flours).

Storage of raw materials is most important in a seasonal industry (e.g., sugar refining, brewing, grain processing and canning). It is usually done in silos, tanks, cellars, bins or cold stores. Storage of the finished products varies according to their nature (liquid or solid), the method of preserving and the method of packaging (loose, in sack or super sack, in bundles, boxes or bottles); and the respective premises must be planned to suit the conditions of handling and preserving (traffic aisles, ease of access, temperature and humidity suited to product, cold-storage installations). Commodities may be held in oxygen-deficient atmospheres or under fumigation while in storage or just before shipment.

Extraction

To extract a specific food product from fruit, cereals or liquids, any of the following methods may be used: crushing, pounding or grinding, extraction by heat (direct or indirect), extraction by solvents, drying and filtration.

Crushing, pounding and grinding are usually preparatory operations—for example, the crushing of cocoa beans and the slicing of sugar beet. In other cases it may be the actual extraction process, as in flour milling.

Heat can be used directly as a means of preparation by extraction, as in roasting (e.g., cocoa, coffee and chicory); in manufacturing it is usually used directly or indirectly in the form of steam (e.g., extraction of edible oils or extraction of sweet juice from thin slices of beet in the sugar industry).

Oils can be extracted equally well by combining and mixing the crushed fruit with solvents that are later eliminated by filtering and reheating. The separation of liquid products is carried out by centrifuging (turbines in a sugar refinery) or by filtering through filter presses in breweries and in oil and fat production.

Production Processes

Operations in processing food products are extremely varied and can be described only after individual study of each industry, but the following general procedures are used: fermentation, cooking, dehydration and distillation.

Fermentation, obtained usually by addition of a micro-organism to the previously prepared product, is practiced in bakeries, breweries, the wine and spirits industry and the cheese products industry. (See also the chapter Beverage industry.)

Cooking occurs in many manufacturing operations: canning and preserving of meat, fish, vegetables and fruits; ready-to-serve meat-processing plants (e.g., chicken nuggets); in bakeries, biscuit making, breweries; and so on. In other cases, cooking is done in a vacuum-sealed container and produces a concentration of the product (e.g., sugar refining and tomato-paste production).

Besides the drying of products by the sun, as with many tropical fruits, dehydration can be carried out in hot air (fixed dryers or drying tunnels), by contact (on a drying drum heated by steam, such as in the instant-coffee industry and the tea industry), vacuum drying (often combined with filtering) and lyophilization (freeze drying), where the product is first frozen solid and then dried by vacuum in a heated chamber.

Distillation is used in the making of spirits. The fermented liquid, treated to separate grain or fruit, is vaporized in a still; the condensed vapour is then collected as liquid ethyl alcohol.

Preservation Processes

It is important to prevent any deterioration of food products, as much for the quality of the products as for the more serious risk of contamination or threat to the consumers’ health.

There are six basic methods of food preservation:

1. radiation sterilization
2. antibiotic sterilization
3. chemical action
4. dehydration
5. refrigeration.

Briefly, the first three methods destroy microbial life; the latter merely inhibit growth. Raw ingredients such as fish and meat, fruit or vegetables are taken fresh and preserved by one of the above methods, or a mixture of different foods are processed to form a product or dish, which is then preserved. Such products include soups, meat dishes and puddings.

Food preservation goes back to the last Ice Age, about 15,000 BC, when Cro-Magnon humans discovered for the first time a way of preserving food by smoking it. The evidence for this lies in the caves at Les Eyzies in the Dordogne in France, where this way of life is well portrayed in carvings, engravings and paintings. From then to the present day, although many methods have been used and still are, heat remains one of the principal cornerstones of food preservation.

High-temperature processes can destroy bacteria, depending on the cooking temperature and duration. Sterilization (mainly used in canneries) involves submitting the already canned product to the action of steam, generally in a closed container such as an autoclave or continuous cooker. Pasteurization—the term is particularly reserved for liquids such as fruit juice, beer, milk or cream—is carried out at a lower temperature and for a short time. Smoking is carried out mainly on fish, ham and bacon, assuring dehydration and giving a distinctive flavor.

Ionizing radiation sterilization is used heavily on spices in some countries to reduce wastage and spoilage. “Radiation pasteurization” using much lower doses enables the refrigerated shelf life of many foods to be considerably extended. However, sterilizing canned foods with radiation requires such high dosage that unacceptable flavours and odours result.

Ionizing radiation has two other well recognized uses in the food industry—the screening of food packs for foreign matter and monitoring to detect underfilling.

Microwave sterilization is another type of electromagnetic emission that is currently finding use in the food industry. It is used for rapidly thawing raw frozen ingredients before further processing, as well as for heating frozen cooked foods in 2 to 3 minutes. Such a method, with its low moisture content loss, preserves the appearance and flavour of the food.

Drying is a common preservation process. Sun drying is the oldest and most widely used method of food preservation. Today foodstuffs may be dried in air, superheated steam, in vacuum, in inert gas and by direct application of heat. Many types of dryers exist, the particular type being dependent on the nature of the material, the desired form of finished product and so on. Dehydration is a process in which heat is transferred into the water in the food, which is vapourized. The water vapour is then removed.

Low-temperature processes involve storage in a cold store (the temperature determined by the nature of the products), freezing and deep-freezing, which allows foodstuffs to be preserved in their naturally fresh state, by various methods of slow or rapid freezing.

With freeze drying, the material to be dried is frozen and placed in a sealed chamber. The chamber pressure is reduced and maintained at a value below 1 mm Hg. Heat is applied to the material, the surface ice heats up and the resultant water vapour is drawn off by the vacuum system. As the ice boundary recedes into the material, the ice sublimes in situ and the water percolates to the surface through the pore structure of the material.

Intermediate-moisture foods are foodstuffs that contain relatively large amounts of water (5 to 30%) and yet do not support microbial growth. The technology, which is difficult, is a spin-off from space travel. Open-shelf stability is achieved by suitable control of acidity, redox potential, humectants and preservatives. Most developments to date have been in foods for pet animals.

Whatever the preservation process, the food to be preserved has first to be prepared. Meat preservation involves a butchery department; fish needs cleaning and gutting, filleting, curing and so on. Before fruit and vegetables can be preserved they have to be washed, cleaned, blanched, perhaps graded, peeled, stalked, shelled and stoned. Many of the ingredients have to be chopped, sliced, minced or pressed.

Packaging

There are many methods of packaging food, including canning, aseptic packaging and frozen packaging.

Canning

The conventional method of canning is based on the original work of Appert in France, for which in 1810 the French government awarded him a prize of 12,000 francs. He preserved food in glass containers. In Dartford, England, in 1812, Donkin and Hall set up the first cannery using tinned iron containers.

Today the world uses several million tonnes of tinplate annually for the canning industry, and a substantial amount of preserved food is packed into glass jars. The process of canning consists of taking cleaned food, raw or partly cooked but not intentionally sterilized, and packing it into a can that is sealed with a lid. The can is then heated, usually by steam under pressure, to a certain temperature for a period of time to allow penetration of the heat to the centre of the can, destroying the microbial life. The can is then cooled in air or chlorinated water, after which it is labelled and packed.

Changes in processing have occurred over the years. Continuous sterilizers cause less damage to cans by impact and allow cooling and drying in a closed atmosphere. Foods can also be heat preserved in retortable pouches. These are bags of small cross-sectional area made from laminates of aluminium and heat-sealable plastics. The process is the same as for conventional canning, but better taste properties are claimed for the products because sterilization times can be reduced. Very careful control of the retorting process is essential to avoid damage to the heat seals with subsequent bacterial spoilage.

Aseptic packaging

There have been recent developments in the aseptic packaging of food. The process is fundamentally different from conventional canning. In the aseptic method the food container and closure are sterilized separately, and the filling and closing are done in a sterile atmosphere. Product quality is optimal because heat treatment of the foodstuff can be controlled precisely and is independent of the size or material of the container. Of concern is employee exposure to the sterilizing agents. It is likely that the method will become more widely used because overall it should result in energy savings. To date most progress has been made with liquids and purées sterilized by the so-called HTST process, in which the product is heated to a high temperature for a few seconds. Developments on particulate foodstuffs will follow. One likely benefit in food factories will be the reduction of noise if rigid metallic containers are replaced. Such containers may also cause problems by contaminating preserved food with lead and tin. These are minimized by new-type two-piece containers drawn from lacquered tinplate and three-piece containers with welded instead of soldered side seams.

Frozen packaging

The frozen food industry utilizes all methods of deep-freezing fresh food at temperatures below their freezing point, thus forming ice crystals in the watery tissues. The food may be frozen raw or partially cooked (e.g., animal carcasses or made-up meat dishes, fish or fish products, vegetables, fruits, poultry, eggs, ready-made meals, bread and cakes). Frozen perishable products can be transported over long distances and stored for processing and/or sale when demand arises, and seasonal products can be available at all times.

Food for freezing must be in prime condition and prepared under strict hygienic control. Packaging materials should be vapour- and aroma-proof and resistant to low temperatures. The quality of the product depends on the rate of freezing: if too slow, the structure of the food may be damaged by large ice crystals and enzymatic and microbiological properties destroyed. Small items, such as shrimps and peas, can be frozen quickly, which makes for an improvement in quality.

The various methods of freezing include: air freezing, blast freezing, fluid-bed freezing, fluid freezing, contact freezing, liqui-freezing and dehydro-freezing.

Air freezing in its simplest form involves placing food in trays on shelves in a cold store at approximately –30 ºC for a time varying from a few hours to 3 days, depending on size. Blast freezing, a more complicated technique, uses a rapidly circulating stream of cold air, sometimes combined with cold spirals, which removes heat by means of radiation. Temperatures range between –40 and –50 ºC, and the maximum air speed is 5 m/s. Blast freezing may be carried out in tunnel freezers, often equipped with conveyors to carry the food through to cold-storage rooms. When the freezer is adjacent to the cold store, the tunnel is often closed with an air curtain instead of doors.

Fluid-bed freezing is used for chopped or sliced vegetables, peas and so on, which are placed on a perforated belt through which a stream of air is blown. Each item is coated with ice and thus retains its shape and separateness. The frozen vegetables may be stored in large containers and repackaged when needed in small units. In fluid freezing (one of the oldest known methods) the food, usually fish, is immersed in a strong solution of brine. Salt may penetrate unwrapped goods and even wrappings, affecting the flavour and hastening rancidity. This method had declined in use but is now gaining ground again as more effective plastic wrapping materials are developed. Poultry is frozen by a combination of the fluid- and air-freezing methods. Each bird, packed in polyethylene or similar material, is first sprayed or immersed in a fluid to freeze its outer layer; the inside is afterwards frozen in a blast freezer.

Contact freezing is the common method for foodstuffs packed in cartons, which are placed between hollow shelves through which a cooling fluid is circulated; the shelves are pressed flat against the cartons, usually by hydraulic pressure.

In liqui-freezing, the product is placed on a conveyor belt which is passed through a tank of liquid nitrogen (or occasionally liquid carbon dioxide) or through a tunnel where liquid nitrogen is sprayed. Freezing occurs at a temperature as low as –196 ºC, and not every type of product or wrapping can withstand this cold. Dehydro-freezing, which removes some of the water before freezing, is used for certain vegetables and fruits. A considerable reduction of weight is achieved, involving lower transport, storage and wrapping costs.

During cold storage, the product must be kept at a temperature of –25 to –30 ºC, and good air circulation must be maintained. Transport of frozen goods has to be in refrigerated wagons, lorries, ships and so on, and during loading and unloading, the goods must be exposed to as little heat as possible. Usually, firms producing frozen food also prepare the raw material, but sometimes this treatment is carried out in separate establishments. In beef and poultry operations, carbon dioxide is often used to cool and preserve product during shipping.

Hazards and Their Prevention

Injury hazards

The most common causes of injuries in the food industry are hand tools, especially knives; operation of machinery; collisions with moving or stationary objects; falls or slips; and burns.

Injuries caused by knives in meat and fish preparation can be minimized by design and maintenance, adequate work areas, selection of the right knife for the job, provision of tough protective gloves and aprons and correct training of workers on both the sharpening and the use of the knife. Mechanical cutting devices also pose a hazard, and good maintenance and adequate training of workers is critical to prevent injuries (see figure 1).

Figure 1. Carving frozen whale meat on a band saw without adequate machine guarding and electrical precautions, Japan, 1989

L. Manderson

Although accidents involving transmission machinery are relatively infrequent, they are likely to be serious. Risks related to machines and handling systems must be studied individually in each industry. Handling problems can be addressed by close examination of injury history for each particular process and by use of appropriate personal protection, such as foot and leg protection, hand and arm protection and eye and face protection. Risks from machinery can be prevented by secure machinery guarding. Mechanical handling equipment, especially conveyors, is widely employed, and particular attention should be paid to in-running nips on such equipment. Filling and closing machines should be totally enclosed except for the intake and discharge openings. The intakes of conveyor belts and drums, as well as pulleys and gearing, should be securely protected. To prevent cuts in canning, for example, effective arrangements for clearing up sharp tin or broken glass are required. Serious injury due to the inadvertent start-up of transmission machinery during cleaning or maintenance can be avoided by strict lockout/tagout procedures.

Falling accidents are most often caused by:

• The state of the floor. Accidents are possible when floors are uneven, wet or made slippery by the type of surface; by products; by fatty, oily or dusty waste; or, in cold rooms, from humid air condensing on the floors. Anti-slip floors help to prevent slips. Finding the proper surface and cleaning regimen, along with good housekeeping and proper footwear, will help prevent many falls. Curbs around machines containing water will prevent water flowing onto the floor. Good drainage should be provided to remove rapidly any accumulating liquids or spillage that occurs.

• Uncovered pits or drainage channels. Maintenance of covers or barricading of the hazard is necessary.

• Work at heights. Provision of safe means of access to equipment and storage areas, sound ladders and fall protection (including body harnesses and lifelines) can prevent many hazards.

• Steam or dust. Operations that generate steam or dust may not only make the floor slippery but also prevent good visibility.

• Insufficient or inconsistent lighting. Illumination needs to be bright enough for employees to be able to observe the process. The perception of inadequate lighting occurs when warehouses appear dark compared to production areas and people’s eyes do not adjust when moving from one light level to the other.

Burns and scalds from hot liquors and cooking equipment are common; similar injuries arise from steam and hot water used in equipment cleaning. Even more serious accidents can occur due to explosion of boilers or autoclaves due to lack of regular examination, poor employee training, poor procedures or poor maintenance. All steam equipment needs regular and careful maintenance to prevent major explosion or minor leaks.

Electrical installations, especially in wet or damp places, require proper grounding and good maintenance to control the common hazard of electrical shock. In addition to proper grounds, outlets protected with ground fault interrupters (GFIs) are effective in protecting from electrical shock. Proper electrical classification for hazardous environments is critical. Often flavours, extracts and dusty flammable powders such as grain dust, corn starch or sugar (thought of as foodstuffs rather than hazardous chemicals) may require classified electrical equipment to eliminate ignition during process upsets or excursions. Fires may also occur if welding is done around explosive/combustible organic dusts in grain elevators and mills. Explosions may also occur in gas or oil-fired ovens or cooking processes if they are not installed, operated or maintained correctly; provided with the essential safety devices; or if proper safety procedures are not followed (especially in open flame operations).

Strict product sanitation control is vital at all stages of food processing, including in slaughterhouses. Personal and industrial hygiene practices are most important in guarding against infection or contamination of the products. The premises and equipment should be designed to encourage personal hygiene through good, conveniently situated and sanitary washing facilities, showerbaths when necessary, provision and laundering of suitable protective clothing and provision of barrier creams and lotions, where appropriate.

Strict equipment sanitation is also vital to all stages of food processing. During the regular operation of most facilities, safety standards are effective to control equipment hazards. During the sanitation cycle, equipment must be opened up, guards removed and interlock systems disabled. A frustration is that the equipment is designed to run, but clean-up is often an afterthought. A disproportional share of the most serious injuries happen during this part of the process. Injuries are commonly caused by exposure to in-running nip points, hot water, chemicals and acid or base splashes, or by cleaning moving equipment. Dangerous high-pressure hoses which carry hot water also pose a hazard. Lack of equipment-specific procedures, lack of training and the low experience level of the typical new employee pressed into a cleaning job can add to the problem. The hazard is increased when equipment to be cleaned is located in areas that are not easily accessible. An effective lockout/tagout programme is essential. Current best practice to help control the problem is designing of clean-in-place facilities. Some equipment is designed to be self-cleaning by use of high-pressure spray balls and self-scrubbing systems, but too often manual labour is required to address trouble spots. In the meat and poultry industries, for example, all cleaning is manual.

Health hazards

Infections and infectious or parasitic diseases spread by animals or the waste products of animals used in manufacture are common occupational problems in the food industry. These zoonoses include anthrax, brucellosis, the leptospiroses, tularemia, bovine tuberculosis, glanders, erysipeloid, Q fever, foot-and-mouth disease, rabies and so on. Some food handlers may be subject to a wide variety of skin infections, including anthrax, actinomycosis and erysipeloid. Certain dried fruits are infested with mites; this can affect workers in sorting operations.

Apart from specific prophylactic vaccination against infectious diseases, proper gloves, good personal hygiene and the sanitary facilities to enable this (which are a prerequisite of any food industry as a protection to the product) are the most valuable preventive measures. Good washing facilities, including showers, and appropriate protective clothing are essential. Efficient medical care, especially for treatment of minor injuries, is an equally important requirement.

Contact dermatitis and allergies of the skin or respiratory system caused by organic products, animal or vegetable, are also common. Primary dermatitis can be caused by irritants such as acids, alkalis, detergents and water used in cleaning; friction from fruit picking and packing; and the handling of sugar, which is much used in food manufacture. Secondary sensitization results from the handling of many fruits and vegetables. Organic dusts from grain or flour can also cause respiratory diseases (e.g., “baker’s asthma”) and must be controlled. Too often the food industry considers the ingredients they use to be merely ingredients, rather than chemicals that can have health effects when employees are exposed to either industrial strengths or industrial quantities of “normal” household kitchen ingredients.

Cumulative trauma disorders

Many of the meat, poultry, fish and food processing plants involve highly repetitious and forceful work. The very nature of the products is such that manual labour often is needed to manipulate product when inspecting or loading fragile products into packaging or during the scale-up of a product before high-volume equipment is purchased or installed. Further, handling of boxes for shipping can cause back injuries. Three things to watch for are tasks involving extreme postures, high forces or high levels of repetition. Combinations of more than one factor make the problem more critical. Early detection and treatment of affected workers is desirable. Ergonomic redesign of equipment and other changes discussed in specific articles in this chapter will decrease the incidence of these hazards.

Refrigerants such as anhydrous ammonia, methyl chloride and other halogenated aliphatic hydrocarbons used in freezing and cold storage bring risks of poisoning and chemical burns. Emergency planning in addition to the normal fire planning is important. Training of workers in evacuation procedures is also necessary. Escape-type respiratory protection may be needed during evacuation from some areas of the facility. For some chemicals, sensors in the building are used to provide early warning to all employees through a central alarm system to signal the need to evacuate. Worker reactions to increases in ammonia levels must be taken seriously, and affected workers must be evacuated and treated. Ammonia leaks warrant strict attention and contiuous monitoring. Evacuation may be required if levels start to rise, before dangerous levels are reached. A central assembly point should be selected so that those who are evacuated are not in danger of being downwind of the refrigerant leak. Chemical protective clothing will be needed to aggressively approach the system leak to contain the release. Anhydrous ammonia and the less frequently used refrigerants, such as propane, butane, ethane and ethylene, are also flammable and explosive. Leaks from pipes are usually due to inadequate maintenance and can be prevented with adequate attention. Adequate measures should be taken for explosion prevention and firefighting.

Pesticides, fumigants and other hazardous materials must be kept under strict control and used only according to the manufacturer’s guidance. Organophosphate pesticides should only be used when accompanied with biological monitoring to assure the control of exposure.

The traditional tin/lead soldering of the side seam of a food can and the awareness of the problem of lead levels in food products have resulted in studies of environmental lead levels in can-making units and blood lead levels in workers. Evidence has shown both to be raised, but neither the environmental threshold limit value (TLV) nor the currently acceptable blood lead levels have ever been found to be exceeded. Thus, the results are consistent with a “low risk” lead process.

Carbon dioxide, used in cooling refrigerated products that are to be shipped, must also be kept under strict controls. Adequate ventilation must be provided over dry ice bins to prevent the gas from causing ill effects.

Exposure to cold can range from handling and storage of raw materials in winter or in processing and store rooms cooled with “still air”, to extremes of cold in air-blast refrigeration of raw materials, as in the ice cream and frozen foods industry. Cold-store workers may suffer impairment of health through exposure to cold if adequate protective clothing is not supplied. Exposure to cold is most critical for employees with sedentary jobs in very cold environments. Barriers should be used to deflect cold breezes from workers standing near fans used to circulate air. Job rotation to more active or warmer locations is advisable. In large tunnel freezing plants, it may be fatal for workers to stay in the rapidly moving stream of air, even if dressed in polar clothing. It is particularly important to prohibit entry into a tunnel freezer in operation and to make effective interlocking arrangements or use confined-space entry protocol to ensure that freezers cannot be started up while workers are still inside them. Warm lunchrooms and provision of hot drinks will mitigate the effects of cold work.

Heat, often combined with high humidity in cooking and sterilizing, can produce an equally intolerable physical environment, where heat stroke and heat exhaustion are an issue. These conditions are found especially in processing that entails evaporation of solutions, such as tomato paste production, often in countries where hot conditions already prevail. It is also prevalent on kill floors of slaughterhouses. Effective ventilation systems are essential, with special attention to condensation problems. Air conditioning may be necessary in some areas.

A serious health hazard in most modern plants, especially with canning, is exposure to noise. Putting additional high-speed machines in a limited space continues to drive noise levels up, despite best efforts to keep them below 85 dBA. The manufacture, conveying and filling of cans at speeds of up to 1,000 per minute leads to exposure of operators to a noise level of up to 100 dBA at frequencies ranging from 500 to 4,000 Hz, a dose equivalent of about 96 dBA, which if uncontrolled will lead in many cases to noise-induced deafness over a working lifetime. Certain engineering techniques can lead to some noise reduction; these include sound-absorbent mounting, magnetic elevators, nylon-coated cables and speed-matching in can conveyor systems. However, some radical change in the industry, such as the use of plastic containers, is the only hope for the future of producing a reasonably noise-free environment. At present, a hearing conservation programme based on audiometric examinations, hearing-protection equipment and education should be instituted. Noise refuges and personal ear protection should be provided.

Where ionizing radiation is used, the full precautions applicable to such work (e.g., radiation protection, hazard monitoring, health screening and periodic medical examinations) are necessary.

Medical supervision of workers is desirable; many food factories are small and membership in a group medical service may be the most effective way of securing this.

Health and safety committees that effectively involve the entire organization, including production operators, in the development of plant programmes is the key to a safe operation. Too often the food industry is not considered to be particularly hazardous, and a feeling of complacency develops. Often materials used are ones that people are familiar with and hence individuals may not understand the hazards that can arise when industrial strengths or quantities are employed. Plant employees who understand that safety rules and procedures are in place to protect their health and safety and not simply to meet government requirements are key to the development of a quality safety programme. Management must establish practices and policies that will allow employees to develop those beliefs.

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The basic structure of pulp and paper sheets is a felted mat of cellulose fibres held together by hydrogen bonds. Cellulose is a polysaccharide with 600 to 1,500 repeated sugar units. The fibres have high tensile strength, will absorb the additives used to modify pulp into paper and board products, and are supple, chemically stable and white. The purpose of pulping is to separate cellulose fibres from the other components of the fibre source. In the case of wood, these include hemicelluloses (with 15 to 90 repeated sugar units), lignins (highly polymerized and complex, mainly phenyl propane units; they act as the “glue” that cements the fibres together), extractives (fats, waxes, alcohols, phenols, aromatic acids, essential oils, oleoresins, stearols, alkaloids and pigments), and minerals and other inorganics. As shown in table 1, the relative proportions of these components vary according to the fibre source.

Table 1. Chemical constituents of pulp and paper fibre sources (%)

nd = no data available.

Coniferous and deciduous trees are the major fibre sources for pulp and paper. Secondary sources include straws from wheat, rye and rice; canes, such as bagasse; woody stalks from bamboo, flax and hemp; and seed, leaf or bast fibres, such as cotton, abaca and sisal. The majority of pulp is made from virgin fibre, but recycled paper accounts for an increasing proportion of production, up from 20% in 1970 to 33% in 1991. Wood-based production accounted for 88% of worldwide pulp capacity in 1994 (176 million tonnes, figure 1); therefore, the description of pulp and paper processes in the following article focuses on wood-based production. The basic principles apply to other fibres as well.

Figure 1. Worldwide pulp capacities, by pulp type

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It is thought that the word coffee derives from Kaffa, a village in Ethiopia where the plant is thought to have its origin. Some, however, consider that the word stems from qahwa, meaning wine in Arabic. Coffee cultivation spread the world over, starting in Arabia (one species is called Coffea arabica, and a variety is Moka, named after an Arab village), passing through many countries, such as Ceylon, Java, India, the Philippines, Hawaii and Viet Nam, among others, some of which are important producers to this day. In America, coffee was introduced from plants previously adapted to the climate in Amsterdam and Paris, planted in Martinique, Surinam and French Guyana, from where it was brought to Brazil, the largest producing country in the world.

World production may be estimated from figure 1. The 1995–96 crop generated wealth estimated at approximately US$27 million, indicating the economic significance of this product worldwide.

Figure 1. World coffee production for 1995 - 96

The trend towards a global economy, growing competition and the search for technologies with higher productivity also have effects upon coffee cultivation. Mechanization is being disseminated and updated. Moreover, new methods of cultivation are introduced, among them high-density cultivation, in which the distance between plants is being reduced. This modern method increases the number of coffee trees from 3,000 or 4,000 to 100,000 plants per hectare, with an increase in productivity of around 50% over the traditional method. This procedure is important for workers’ health, since lower risks are involved and less herbicide is applied, especially after the third year. On the other hand, there is an increase in the frequency of tree cutting and higher demand for control of fungus disease in the plants.

Coffee is highly sensitive to fluctuations in international commerce; many countries tend to replace coffee with other crops in which financial return is more predictable. In Brazil, for instance, coffee represented 68% of the total volume of exports in 1920; in the 1990s it is only 4%. Coffee is being replaced by                                                                                                                         soy bean, citric fruits, corn, latex and especially sugar cane.

It is extremely difficult to obtain a reliable estimate of the total labour force involved in coffee cultivation because the number of employed workers is quite variable. During harvest, a large number of seasonal workers are hired, to be dismissed soon after the crop is over. Moreover, in small properties, very often workers are not legally registered, and therefore are not shown in official reports. In Brazil in 1993, for a production of 28.5 million coffee bags, the number of workers was estimated at 1.1 million in direct and 4 to 5 million in indirect jobs. If the same parameters are applied to world production for the same year, coffee workers around the world could be estimated at approximately 3.6 million.

It is equally difficult to know the average figure of workers per rural property. In general, small or medium-sized properties are predominant. The sex and age distribution of the working population is equally unknown, even though female population among workers is increasing and children are known to be employed in coffee plantations. Figures for unionized workers vary according to the labour policies in each country, but they are known to be generally scarce.

Operations

Coffee cultivation and treatment involve the following steps: tree abatement; soil preparation; planting (small plants are usually grown in nurseries in the same or in external properties); treatment (soil correction, fertilizing, pest control and terrain cleaning manually or with herbicides); fruit picking (ripe fruit is usually red and therefore called a berry—see figure 2; sieving to get rid of impurities; transportation; washing to remove pulp and membranes; sun drying, revolving grains with a rake, or mechanical drying through hot air blasting; hand separation of grains; storing in silos; and bagging.

Figure 2. High-density coffee cultivation showing berries

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Potential Risks

Risk factors that may affect workers’ health in coffee cultivation are the same as for agricultural workers in general.

From tree abatement and terrain preparation to the final storage of coffee bags, each step may involve several risk factors for workers’ health and safety. Injury risks are present mainly in mechanized processes, tree abatement, terrain preparation, mechanical picking, transportation of coffee and workers as well, fruit treatment (including the risk of boiler explosion) and use of hand tools (very often improvised or without maintenance).

Potential risks of occupational diseases due to physical conditions are related to heat exposure in drying operations, solar radiation, machine noise, ergonomic problems from hand tools, vibration from machinery and tractors, and cold and humidity from outdoor exposure.

The main chemical agents present as potential risks for workers’ health are pesticides and herbicides. Those most often used are gliphosate as an herbicide, copper salts as fungicides and organophosphorus compounds for other pests commonly found on coffee trees. The number of pesticide applications varies according to tree age, soil composition, climatic conditions, vegetation species or variety, cultivation system (e.g., high or low density) and other factors. Spraying is usually done individually with backpack equipment, or from tractors. Large amounts are usually required, and it is said that “without spraying no crop is available”.

Chemical fertilizers may also present a health risk. Often used are compounds derived from boron, zinc, nitrogen, sodium, potassium, calcium, magnesium and sulphur. The release of particles from fertilizer handling should be kept under control.

Biological agents may represent important risks for workers’ health. They may include, for instance, bites or stings from snakes, spiders, bees, mosquitoes and acarids, some of them important as disease vectors. In certain areas, endemic diseases may be serious risks for coffee workers.

Ergonomic, psychosocial and organizational factors are discussed below.

Health Effects

Examples of injuries related to work are cuts from hand tools, sprains and fractures from machines and injuries from tractors. Fatal injuries, even if unusual, have occurred as a result of overturning of tractors or inadequate vehicles used in transportation of workers. When artificial drying is employed, heat sources may cause burns and explosions.

Occupational diseases may result from exposure to solar ultraviolet radiation; cutaneous conditions may range from a simple erythema to skin cancer. Hearing loss among machine operators, pulmonary allergic conditions, poisoning from herbicides and pesticides, callosities, lung diseases, bone and circulatory conditions due to vibration, and muscular and skeletal trouble due to poor ergonomic positions or excessive weight (one coffee bag can weigh 60 kg) are other occupational conditions that may occur among coffee cultivation workers. Although primarily a problem among workers processing coffee beans, green bean handlers have complained of respiratory and eye problems. Coffee bean dust has been associated with occupational dust diseases.

Tropical diseases such as malaria, yellow fever, filariasis, trypanossomiasis, leishmaniasis and onchocercosis are prevalent in certain cultivating areas. Tetanus is still prevalent in many rural areas.

More complex health problems related to psychosocial and organizational factors may also affect coffee workers. Since large numbers of workers are required during harvest, and very few during the rest of the year, seasonal contracts are usually practised, often resulting in difficult health problems.

In many cases, workers leave their families and remain during the harvest season in precarious lodgings under inadequate sanitary conditions. If the planting area is close to town, the farmer will contract only one man in the family. However, to increase the profit, the worker himself may bring his whole family to help, including women and children. In some areas, the number of children at work is so high that schools will be closed during the whole harvest season.

In this type of seasonal activity, workers will turn from one type of cultivation to another, according to each harvest period. Since men leave their families, women are called “widows with living husbands”. Very often, a man will raise another family, away from his original town.

Proper compliance with labour legislation and social security is usually restricted to large plantations, and labour inspection in rural areas is generally ineffective. Health care is usually very limited. Duration of work is extended to many hours daily; weekends and normal vacations are seldom respected.

These psychosocial and organizational factors result in marked deterioration in workers’ health, manifested through early ageing, low life expectancy, increase in prevalence and longer duration of diseases, malnutrition (eating the food taken to the field in cans without heating it has led to workers being given a nickname—boias frias in Portuguese), anaemia and hypovitaminoses leading to loss of disposition to work, mental trouble and other manifestations.

Prevention

Preventive measures concerning coffee are the same that apply to rural work in general. Collective protection includes machine guarding, care in application of pesticides and herbicides, mechanizing operations that require undue effort and energy consumption, and adequate transportation of workers. In high-density plantations, regular cutting will not allow the trees to grow, which will eliminate the use of dangerous and uncomfortable ladders for hand picking. When drying requires the use of boilers, careful periodic preventive maintenance is of utmost importance. Biological pest control and proper selection of species resistant to plagues are important preventive measures concerning pesticides, avoiding workers’ disease and environmental protection as well.

Implementation of the use of recommended PPE is difficult because such equipment is usually not adapted to climatic conditions or to the biotype of workers. Moreover, there is usually no educational orientation to facilitate the use, and the selection of equipment is not always correct. Equipment in general use is restricted to boots, hats and clothing to protect from the weather, even though hand, lung, eye and ear protection may be required.

Prevention to control psychosocial and organizational factors may bring up many difficulties. Workers’ awareness should be raised through educational activities, especially in unions and other workers’ organizations, increasing perceptions about workers’ rights to better living and working conditions; moreover, employers should develop their perceptions concerning their social responsibilities towards the labour force. The State should exercise an effective and constant orientation and enforcement wherever legal action is required. Some countries have developed rules and regulations specifically applicable to rural workers. In Brazil, for example, Rural Regulatory Standards establish general directives concerning safety in rural activities, the organization of occupational health services and safety committees in plantations, use of personal protective equipment and handling of chemicals (pesticides, fertilizers and soil-correcting products).

Health control through occupational medicine should cover the evaluation of health effects due to exposure to pesticides, ultraviolet radiation, excessive noise and many other hazards. It may, in many circumstances, be more necessary to control worm diseases, anaemia, hypertension, behavioural problems, eye defects and similar problems, due to their high prevalence in rural areas. Health education should be stressed, as well as tetanus immunization, including for pregnant workers to prevent neonatal tetanus. In some regions, immunization against yellow fever is necessary. Chemoprophylaxis is recommended in areas where malaria is endemic, together with the use of repellents and a preventive orientation against mosquitoes, until sanitation is adequate to control or suppress vectors of the aetiological agent. Serum against snake poison should be available.

Acknowledgement: The authors are obliged to the cooperation received from Professor Nelson Batista Martin, from the Institute of Rural Economy, State Secretary of Agriculture, Sao Paulo; Andre Nasser and Ricardo Luiz Zucas, from the Brazilian Rural Society; and Monica Levy Costa, from the School Health Center, School of Public Health, Sao Paulo University.

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Migrant and seasonal farmworkers represent a large, global population with the double hazard of occupational health hazards of farming superimposed on a foundation of poverty and migrancy, with its associated health and safety problems. In the United States, for example, there are as many as 5 million migrant and seasonal farmworkers, although precise numbers are not known. As the total farm population has decreased in the United States, the proportion of hired farmworkers has increased. Globally, workers migrate in every region of the world for work, with movement generally from poorer to wealthier countries. In general, migrants are given more hazardous and difficult jobs and have increased rates of illness and injury. Poverty and lack of adequate legal protection exacerbate the risks of occupational and non-occupational disease.

Studies of hazardous exposures and health problems in this population have been limited because of the general paucity of occupational health studies in agriculture and the specific difficulties in studying farmworkers, due to their migratory residence patterns, language and cultural barriers, and limited economic and political resources.

Migrant and seasonal agricultural workers in the United States are predominantly young, Hispanic males, although farmworkers also include whites, blacks, Southeast Asians and other ethnic groups. Almost two-thirds are foreign born; most have low levels of education and do not speak or read English. Poverty is a hallmark of agricultural workers, with over half having family incomes below the poverty level. Substandard working conditions prevail, salaries are low and there are few benefits. For example, less than one-fourth have health insurance. Seasonal and migrant agricultural workers in the United States work about half the year on the farm. Most work is in labour-intensive crops such as harvesting of fruits, nuts or vegetables.

The general health status of agricultural workers directly derives from their working conditions and low income. Deficiencies exist in nutrition, housing, sanitation, education and access to medical care. Crowded living conditions and inadequate nutrition may also contribute to the increased risks of acute, infectious illnesses. Farmworkers see a physician less often than non-farmworking populations, and their visits are overwhelmingly for treatment of acute illnesses and injuries. Preventive care is deficient in farmworker populations, and surveys of farmworker communities find a high prevalence of individuals with medical problems requiring attention. Preventive services such as vision and dental care are seriously deficient, and other preventive services such as immunizations are below the population averages. Anaemia is common, probably reflecting poor nutritional status.

The poverty and other barriers for migrant and seasonal farmworkers generally result in substandard living and working conditions. Many workers still lack access to basic sanitary facilities at the worksite. Living conditions vary from adequate government-maintained housing to substandard shacks and camps used while work exists in a particular area. Poor sanitation and crowding may be particular problems, increasing the risks of infectious diseases in the population. These problems are exacerbated among workers who migrate to follow agricultural work, reducing community resources and interactions at each living site.

Various studies have shown a greater burden of infectious diseases on morbidity and mortality in this population. Parasitic diseases are significantly increased among migrant workers. Increased deaths have been found for tuberculosis, as well as many other chronic diseases such as those of the cardiovascular, respiratory and urinary tracts. The greatest increase in mortality rates is for traumatic injuries, similar to the increase seen for this cause among farmers.

The health status of children of farmworkers is of particular concern. In addition to the stresses of poverty, poor nutrition and poor living conditions, the relative deficiency of preventive health services has a particularly serious impact on children. They also are exposed to the hazards of farming at a young age, both by living in the farming environment and by doing agricultural work. Children under 5 years of age are most at risk of unintentional injury from agricultural hazards such as machinery and farm animals. Above 10 years of age, many children begin working, particularly at times of acute labour need such as during harvesting. Working children may not have the necessary physical strength and coordination for farm labour, nor do they have adequate judgement for many situations. Exposure to agrochemicals is a particular problem, since children may not be aware of recent field application or be able to read warnings on chemical containers.

Farmworkers are at increased risk of pesticide illness during work in the fields. Exposures most commonly occur from direct contact with the spray of application equipment, from prolonged contact with recently sprayed foliage or from drift of pesticide applied by aircraft or other spray equipment. Re-entry intervals exist in some countries to prevent foliar contact while the pesticide on foliage is still toxic, but many places have no re-entry intervals, or they may not be obeyed to hasten the harvest. Mass poisonings from pesticide exposure continue to occur among agricultural workers.

The greatest workplace hazard to farmworkers is from sprains, strains and traumatic injuries. The risk of these outcomes is increased by the repetitive nature of much labour-intensive agricultural work, which often involves workers bending or stooping to reach crops. Some harvesting tasks may require the worker to carry heavy bags full of the harvested commodity, often while balancing on a ladder. There is substantial risk of traumatic injuries and musculoskeletal strains in this situation.

In the United States, one of the most serious causes of fatal injuries to farmworkers is motor vehicle accidents. These often occur when farmworkers are driving or being driven to or from the fields very early or late in the day on unsafe rural roads. Collisions may also occur with slow-moving farm equipment.

Dust and chemical exposures result in an increased risk of respiratory symptoms and disease in farmworkers. The specific hazard will vary with the local conditions and commodities. For example, in dry-climate farming, inorganic dust exposure may result in chronic bronchitis and dust-borne diseases of the lung.

Skin disease is the most common work-related health problem among agricultural workers. There are numerous causes of skin disease in this population, including trauma from using hand equipment such as clippers, irritants and allergens in agrochemicals, allergenic plant and animal materials (including poison ivy and poison oak), nettles and other irritant plants, skin infections caused or exacerbated by heat or prolonged water contact, and sun exposure (which can cause skin cancer).

Many other chronic diseases may be more common among migrant and seasonal farmworkers, but data on actual risks are limited. These include cancer; adverse reproductive outcomes, including miscarriage, infertility and birth defects; and chronic neurologic disorders. All of these outcomes have been observed in other farming populations, or those with high-level exposure to various agricultural toxins, but little is known about actual risk in farmworkers.

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