Howard, Ninica L.

Howard, Ninica L.

Address: SHARP, Division of Labor and Industries, PO Box 44330, Olympia, WA 98504-4330

Country: United States

Phone: 1 360 902-6557; Fax:

Past position(s): Research Assistant, Work Environment Department, University of Massachusetts, Lowell

Education: MS

 

Monday, 28 March 2011 18:46

Health Problems and Disease Patterns

The domestication of animals occurred independently in a number of areas of the Old and New World over 10,000 years ago. Until domestication, hunting and gathering was the predominant subsistence pattern. The transformation to human control over animal and plant production and reproduction processes resulted in revolutionary changes in the structure of human societies and their relationships to the environment. The change to agriculture marked an increase in labour intensity and work time spent in food procurement-related activities. Small nuclear families, adapted to nomadic hunting and gathering groups, were transformed into large, extended, sedentary social units suited to labour-intensive domesticated food production.

The domestication of animals increased human susceptibility to animal-related injuries and diseases. Larger non-nomadic populations quartered in close proximity to animals provided greater opportunity for transmission of disease between animals and humans. The development of larger herds of more intensely handled livestock also increased the likelihood of injuries. Throughout the world, differing forms of animal agriculture are associated with varying risks for injury and disease. For example, the 50 million inhabitants who practice swidden (cut and burn) agriculture in equatorial regions face different problems from the 35 million pastoral nomads across Scandinavia and through central Asia or the 48 million food producers who practise an industrialized form of agriculture.

In this article, we provide an overview of selected injury patterns, infectious diseases, respiratory diseases and skin diseases associated with livestock production. The treatment is topically and geographically uneven because most research has been conducted in industrialized countries, where intensive forms of livestock production are common.

Overview

Types of human health problems and disease patterns associated with livestock production can be grouped according to the type of contact between animals and people (see table 1). Contact can occur via direct physical interaction, or contact with an organic or inorganic agent. Health problems associated with all types of livestock production can be grouped into each of these areas.


Table 1. Types of human health problems associated with livestock production

Health problems from direct physical contact

Allergic contact dermatitis
Allergic rhinitis
Bites, kicks, crushing
Envenomation and possible hypersensitivity
Asthma
Scratches
Traumatic injury

Health problems from organic agents

Agrochemical poisoning
Antibiotic resistance
Chronic bronchitis
Contact dermatitis
Allergies from drug residue food exposures
Food-borne illnesses
“Farmer’s lung”
Hypersensitivity pneumonitis
Mucous membrane irritation
Occupational asthma
Organic dust toxic syndrome (ODTS)
Allergies from pharmaceutical exposures
Zoonotic diseases

Health problems from physical agents

Hearing loss
Machinery-related trauma
Methane emission and greenhouse effect
Musculoskeletal disorders
Stress


Direct human contact with livestock ranges from the brute force of large animals such as the Chinese buffalo to the undetected skin contact by microscopic hairs of the Japanese oriental tussock moth. A corresponding range of health problems can result, from the temporary irritant to the debilitating physical blow. Notable problems include traumatic injuries from handling large livestock, venom hypersensitivity or toxicosis from venomous arthropod bites and stings, and contact and allergic contact skin dermatitis.

A number of organic agents utilize various pathways from livestock to humans, resulting in a range of health problems. Among the most globally important are zoonotic diseases. Over 150 zoonotic diseases have been identified worldwide, with approximately 40 significant for human health (Donham 1985). The importance of zoonotic diseases depends on regional factors such as agricultural practices, environment and a region’s social and economic status. The health consequences of zoonotic diseases range from the relatively benign flu-like symptoms of brucellosis to debilitating tuberculosis or potentially lethal strains of Escherichia coli or rabies.

Other organic agents include those associated with respiratory disease. Intensive livestock production systems in confined buildings create enclosed environments where dust, including microbes and their by-products, becomes concentrated and aerosolized along with gases that are in turned breathed by people. Approximately 33% of swine confinement workers in the United States suffer from organic dust toxic syndrome (ODTS) (Thorne et al. 1996).

Comparable problems exist in dairy barns, where dust containing endotoxin and/or other biologically active agents in the environment contributes to bronchitis, occupational asthma and inflammation of the mucous membrane. While these problems are most notable in developed countries where industrialized agriculture is widespread, the increasing export of confined livestock production technologies to developing areas such as Southeast Asia and Central America increases the risks for workers there.

Health problems from physical agents typically involve tools or machinery either directly or indirectly involved with livestock production in the agricultural work environment. Tractors are the leading cause of farm fatalities in developed countries. In addition, elevated rates of hearing loss associated with machinery and confined livestock production noises, and musculoskeletal disorders from repetitive motions, are also consequences of industrialized forms of animal agriculture. Agricultural industrialization, characterized by the use of capital-intensive technologies which interface between humans and the physical environment to produce food, is behind the growth of physical agents as significant livestock-related health factors.

Injuries

Direct contact with livestock is a leading cause of injuries in many industrialized regions of the world. In the United States, the national Traumatic Injury Surveillance of Farmers (NIOSH 1993) indicates that livestock is the primary source of injury, with cattle, swine and sheep constituting 18% of all agricultural injuries and accounting for the highest rate of lost workdays. This is consistent with a 1980-81 survey conducted by the US National Safety Council (National Safety Council 1982).

Regional US studies consistently show livestock as a leading cause of injury in agricultural work. Early work on hospital visits by farmers in New York from 1929 to 1948 revealed livestock accounting for 17% of farm-related injuries, second only to machinery (Calandruccio and Powers 1949). Such trends continue, as research indicates livestock account for at least one-third of agricultural injuries among Vermont dairy farmers (Waller 1992), 19% of injuries among a random sample of Alabama farmers (Zhou and Roseman 1995), and 24% of injuries among Iowa farmers (Iowa Department of Public Health 1995). One of the few studies to analyse risk factors for livestock-specific injuries indicates such injuries may be related to the organization of production and specific features of the livestock rearing environment (Layde et al. 1996).

Evidence from other industrialized agricultural areas of the world reveals similar patterns. Research from Australia indicates that livestock workers have the second-highest occupational fatal injury rates in the country (Erlich et al. 1993). A study of accident records and emergency department visits of British farmers in West Wales (Cameron and Bishop 1992) reveals livestock were the leading source of injuries, accounting for 35% of farm-related accidents. In Denmark, a study of 257 hospital-treated agricultural injuries revealed livestock as the second-leading cause of injuries, accounting for 36% of injuries treated (Carstensen, Lauritsen and Rasmussen 1995). Surveillance research is necessary to address the lack of systematic data on livestock-related injury rates in developing areas of the world.

Prevention of livestock-related injuries involves understanding animal behaviour and respecting dangers by acting appropriately and using appropriate control technologies. Understanding animal habits related to feeding behaviours and environmental fluctuations, social relationships such as animals isolated from their herd, nurturing and protective instincts of female animals and the variable territorial nature and feeding patterns of livestock are critical in reducing the risk of injury. Prevention of injury also depends on using and maintaining livestock control equipment such as fences, pens, stalls and cages. Children are at particular risk and should be supervised in designated play areas well away from livestock holding areas.

Infectious Diseases

Zoonotic diseases can be classified according to their modes of transmission, which are in turn linked to forms of agriculture, human social organization and the ecosystem. The four general routes of transmission are:

  1. direct single vertebrate host
  2. cyclical multiple vertebrate host
  3. combination vertebrate-invertebrate host
  4. inanimate intermediary host.

Zoonotic diseases can be generally characterized as follows: they are non-fatal, infrequently diagnosed and sporadic rather than epidemic; they mimic other diseases; and humans are typically the dead-end hosts. Primary zoonotic diseases by region are listed in table 2.

Table 2. Primary zoonoses by world region

Common name

Principal source

Region

Anthrax

Mammals

Eastern Mediterranean, West and Southeast Asia, Latin America

Brucellosis

Goats, sheep, cattle, swine

Europe, Mediterranean area, United States

Encephalitis, arthropod-borne

Birds, sheep, rodents

Africa, Australia, Central Europe, Far East, Latin America, Russia, United States

Hydatidosis

Dogs, ruminants, swine, wild carnivores

Eastern Mediterranean, southern South America, South and East Africa, New Zealand, southern Australia, Siberia

Leptospirosis

Rodents, cattle, swine, wild carnivores, horses

Worldwide, more prevalent in Caribbean

Q fever

Cattle, goats, sheep

Worldwide

Rabies

Dogs, cats, wild carnivores, bats

Worldwide

Salmonellosis

Birds, mammals

Worldwide, most prevalent in regions with industrial agriculture and higher use of antibiotics

Trichinosis

Swine, wild carnivores, Arctic animals

Argentina, Brazil, Central Europe, Chile North America, Spain

Tuberculosis

Cattle, dogs, goats

Worldwide, most prevalent in developing countries

 

Rates of zoonotic diseases among human populations are largely unknown owing to the lack of epidemiological data and to misdiagnoses. Even in industrialized countries such as the United States, zoonotic diseases such as leptospirosis are frequently mistaken for influenza. Symptoms are non-specific, making diagnosis difficult, a characteristic of many zoonoses.

Prevention of zoonotic diseases consists of a combination of disease eradication, animal vaccinations, human vaccinations, work environment sanitation, cleaning and protecting open wounds, appropriate food handling and preparation techniques (such as pasteurization of milk and thorough cooking of meat), use of personal protection equipment (such as boots in rice fields) and prudent use of antibiotics to reduce the growth of resistant strains. Control technologies and preventive behaviours should be conceptualized in terms of pathways, agents and hosts and specifically targeted to the four routes of transmission.

Respiratory Diseases

Given the variety and extent of exposures related to livestock production, respiratory diseases may be the major health problem. Studies in some sectors of livestock production in developed areas of the world reveal that 25% of livestock workers suffer from some form of respiratory disease (Thorne et al. 1996). The kinds of work most commonly associated with respiratory problems include grain production and handling and working in animal confinement units and dairy farming.

Agricultural respiratory diseases may result from exposures to a variety of dusts, gases, agricultural chemicals and infectious agents. Dust exposures may be divided into those primarily consisting of organic components and those consisting mainly of inorganic components. Field dust is the primary source of inorganic dust exposures. Organic dust is the major respiratory exposure to agricultural production workers. Disease results from periodic short-term exposures to agricultural organic dust containing large numbers of microbes.

ODTS is the acute flu-like illness seen following periodic short-term exposure to high concentrations of dust (Donham 1986). This syndrome has features very similar to those of acute farmer’s lung, but does not carry the risk of pulmonary impairment associated with farmer’s lung. Bronchitis affecting agricultural workers has both an acute and chronic form (Rylander 1994). Asthma, as defined by reversible airway obstruction associated with airway inflammation, can also be caused by agricultural exposures. In most cases this type of asthma is related to chronic inflammation of the airways rather than a specific allergy.

A second common exposure pattern is daily exposure to a lower level of organic dust. Typically, total dust levels are 2 to 9 mg/m3, microbe counts are at 103 to 105 organisms/m3 and endotoxin concentration is 50 to 900 EU/m3. Examples of such exposures include work in a swine confinement unit, a dairy barn or a poultry-growing facility. Usual symptoms seen with these exposures include those of acute and chronic bronchitis, an asthma-like syndrome and symptoms of mucous membrane irritation.

Gases play an important role in causing lung disorders in the agricultural setting. In swine confinement buildings and in poultry facilities, ammonia levels often contribute to respiratory problems. Exposure to the fertilizer anhydrous ammonia has both acute and long-term effects on the respiratory tract. Acute poisoning from hydrogen sulphide gas released from manure storage facilities in dairy barns and swine confinement units can cause fatalities. Inhalation of insecticidal fumigants can also lead to death.

Prevention of respiratory illnesses may be aided by controlling the source of dusts and other agents. In livestock buildings, this includes managing a correctly designed ventilation system and frequent cleaning to prevent build-up of dust. However, engineering controls alone are likely insufficient. Correct selection and use of a dust respirator is also needed. Alternatives to confinement operations can also be considered, including pasture-based and partially enclosed production arrangements, which can be as profitable as confined operations, particularly when occupational health costs are considered.

Skin Problems

Skin problems can be categorized as contact dermatitis, sun-related, infectious or insect-induced. Estimates indicate that agricultural workers are at highest occupational risk for certain dermatoses (Mathias 1989). While prevalence rates are lacking, particularly in developing regions, studies in the United States indicate that occupational skin disease may account for up to 70% of all occupational diseases among agricultural workers in certain regions (Hogan and Lane 1986).

There are three types of contact dermatoses: irritant dermatitis, allergic dermatitis and photocontact dermatitis. The most common form is irritant contact dermatitis, while allergic contact dermatitis is less common and photocontact reactions are rare (Zuehlke, Mutel and Donham 1980). Common sources of contact dermatitis on the farm include fertilizers, plants and pesticides. Of particular note is dermatitis from contact with livestock feed. Feeds containing additives such as antibiotics may result in allergic dermatitis.

Light-complexioned farmers in developing areas of the world are at particular risk for chronic sun-induced skin problems, including wrinkling, actinic keratoses (scaly non-cancerous lesions) and skin cancer. The two most common types of skin cancer are squamous and basal cell carcinomas. Epidemiological work in Canada indicates that farmers are at higher risk for squamous cell carcinoma than non-farmers (Hogan and Lane 1986). Squamous cell carcinomas often arise from actinic keratoses. Approximately 2 out of 100 squamous cell carcinomas metastasize, and they are most common on the lips. Basal cell carcinomas are more common and occur on the face and ears. While locally destructive, basal cell carcinomas rarely metastasize.

Infectious dermatoses most relevant for livestock workers are ringworm (dermatophytic fungi), orf (contagious ecthyma) and milker’s nodule. Ringworm infections are superficial skin infections that appear as red scaling lesions that result from contact with infected livestock, particularly dairy cattle. A study from India, where cattle generally roam free, revealed over 5% of rural inhabitants suffering from ringworm infections (Chaterjee et al. 1980). Orf, by contrast, is a pox virus usually contracted from infected sheep or goats. The result is typically lesions on the backs of hands or fingers which usually disappear with some scarring in about 6 weeks. Milker’s nodules result from infection with the pseudocowpox poxvirus, typically from contact with infected udders or teats of milk cows. These lesions appear similar to those of orf, though they are more often multiple.

Insect-induced dermatoses result primarily from bites and stings. Infections from mites that parasitize livestock or contaminate grains is particularly notable among livestock handlers. Chigger bites and scabies are typical skin problems from mites that result in various forms of reddened irritations that usually heal spontaneously. More serious are bites and stings from various insects such as bees, wasps, hornets or ants that result in anaphylactic reactions. Anaphylactic shock is a rare hypersensitivity reaction that occurs with an overproduction of chemicals emitted from white blood cells that result in constriction of the airways and can lead to cardiac arrest.

All of these skin problems are largely preventable. Contact dermatitis can be prevented by reducing exposures through use of protective clothing, gloves and appropriate personal hygiene. Additionally, insect-related problems can be prevented by wearing light-coloured and nonflowery clothing and by avoiding scented skin applications. The risk of skin cancer can be dramatically reduced by using appropriate clothing to minimize exposure, such as a wide-brimmed hat. Use of appropriate sunscreen lotions can also be helpful, but should not be relied upon.

Conclusion

The number of livestock worldwide has grown apace with the increase in human population. There are approximately 4 billion cattle, pigs, sheep, goats, horses, buffalo and camels in the world (Durning and Brough 1992). However, there is a notable lack of data on livestock-related human health problems in developing areas of the world such as China and India, where much of the livestock currently reside and where future growth is likely to occur. However, given the emergence of industrialized agriculture worldwide, it can be anticipated that many of the health problems documented in North American and European livestock production will likely accompany the emergence of industrialized livestock production elsewhere. It is also anticipated that health services in these areas will be inadequate to deal with the health and safety consequences of industrialized livestock production generally described here.

The worldwide emergence of industrialized livestock production with its attendant human health consequences will accompany fundamental changes in the social, economic and political order comparable to those that followed from the domestication of animals over 10,000 years ago. Preventing human health problems will require broad understanding and appropriate engagement of these new forms of human adaptation and the place of livestock production within them.

 

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Monday, 21 March 2011 15:29

Health Problems and Disease Patterns

Teachers comprise a large and growing segment of the workforce in many countries. For example, over 4.2 million workers were classified as preschool through high school teachers in the United States in 1992. In addition to classroom teachers, other professional and technical workers are employed by schools, including custodial and maintenance workers, nurses, food service workers and mechanics.

Teaching has not traditionally been regarded as an occupation that entails exposure to hazardous substances. Consequently, few studies of occupationally related health problems have been carried out. Nevertheless, school teachers and other school personnel may be exposed to a wide variety of recognized physical, chemical, biological and other occupational hazards.

Indoor air pollution is an important cause of acute illnesses in teachers. A major source of indoor air pollution is inadequate maintenance of heating, ventilation and air conditioning systems (HVAC). Contamination of HVAC systems can cause acute respiratory and dermatological illnesses. Newly constructed or renovated school buildings release chemicals, dusts and vapours into the air. Other sources of indoor air pollution are roofing, insulation, carpets, drapes and furniture, paint, caulk and other chemicals. Unrepaired water damage, as from roof leakage, can lead to the growth of micro-organisms in building materials and ventilation systems and the release of bioaerosols that affect the respiratory systems of teachers and students alike. Contamination of school buildings by micro-organisms can cause severe health conditions such as pneumonia, upper respiratory infections, asthma and allergic rhinitis.

Teachers who specialize in certain technical fields may be exposed to specific occupational hazards. For example, arts and craft teachers frequently encounter a variety of chemicals, including organic solvents, pigments and dyes, metals and metal compounds, minerals and plastics (Rossol 1990). Other art materials cause allergic reactions. Exposure to many of these materials is strictly regulated in the industrial workplace but not in the classroom. Chemistry and biology teachers work with toxic chemicals such as formaldehyde and other biohazards in school laboratories. Shop teachers work in dusty environments and may be exposed to high levels of wood dust and cleaning materials, as well as high noise levels.

Teaching is an occupation that is often characterized by a high degree of stress, absenteeism and burnout. There are many sources of teacher stress, which may vary with grade level. They include administrative and curriculum concerns, career advancement, student motivation, class size, role conflict and job security. Stress may also arise from dealing with children’s misbehaviours and possibly violence and weapons in schools, in addition to physical or environmental hazards such as noise. For example, desirable classroom sound levels are 40 to 50 decibels (dB) (Silverstone 1981), whereas in one survey of several schools, classroom sound levels averaged between 59 and 65 dB (Orloske and Leddo 1981). Teachers who are employed in second jobs after work or during the summer may be exposed to additional workplace hazards that can affect performance and health. The fact that the majority of teachers are women (three-fourths of all teachers in the United States are women) raises the question of how the dual role of worker and mother may affect women’s health. However, despite perceived high levels of stress, the rate of cardiovascular disease mortality in teachers was lower than in other occupations in several studies (Herloff and Jarvholm 1989), which could be due to lower prevalence of smoking and less consumption of alcohol.

There is a growing concern that some school environments may include cancer-causing materials such as asbestos, electromagnetic fields (EMF), lead, pesticides, radon and indoor air pollution (Regents Advisory Committee on Environmental Quality in Schools 1994). Asbestos exposure is a special concern among custodial and maintenance workers. A high prevalence of abnormalities associated with asbestos-related diseases has been documented in school custodians and maintenance employees (Anderson et al. 1992). The airborne concentration of asbestos has been reported higher in certain schools than in other buildings (Lee et al. 1992).

Some school buildings were built near high-voltage transmission power lines, which are sources of EMF. Exposure to EMF also comes from video display units or exposed wiring. Excess exposure to EMF has been linked to the incidence of leukaemia as well as breast and brain cancers in some studies (Savitz 1993). Another source of concern is exposure to pesticides that are applied to control the spread of insect and vermin populations in schools. It has been hypothesized that pesticide residues measured in adipose tissue and serum of breast cancer patients may be related to the development of this disease (Wolff et al. 1993).

The large proportion of teachers who are women has led to concerns about possible breast cancer risks. Unexplained increased breast cancer rates have been found in several studies. Using death certificates collected in 23 states in the United States between 1979 and 1987, the proportionate mortality ratios (PMRs) for breast cancer were 162 for White teachers and 214 for Black teachers (Rubin et al. 1993). Increased PMRs for breast cancer were also reported among teachers in New Jersey and in the Portland-Vancouver area (Rosenman 1994; Morton 1995). While these increases in observed rates have so far not been linked either to specific environmental factors or to other known risk factors for breast cancer, they have given rise to heightened breast cancer awareness among some teachers’ organizations, resulting in screening and early detection campaigns.

 

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Thursday, 10 March 2011 16:57

Health Problems and Disease Patterns

Work in the fishing and fish-processing industry shows a clear differentiation according to gender, with the men traditionally doing the actual fishing while the women work at fish processing on shore. Many of the persons working on fishing vessels may be looked upon as unskilled; the deckhands, for instance, receive their training in the work on board. The navigators (captain, skipper and mate), the machine room personnel (engineer, machinist and stoker), the radio operators and the cooks all have different educational backgrounds. The main assignment is to fish; other tasks include loading of the vessel, which is done on the open sea, followed by the fish processing, which takes place to various stages of completion. The only common exposure of these groups occurs during their stay on board the vessel, which is in constant motion both while they are working and resting. Fish processing on shore will be dealt with later.

Accidents

The most dangerous work tasks for the individual fishers are related to the setting out and hauling in of the fishing gear. In trawler fishing, for example, the trawl is laid out in a sequence of tasks involving the complicated coordination of different types of winches (see “Major sectors and processes” in this chapter). All operations take place at great speed, and teamwork is absolutely essential. While setting the trawl, the connecting of the trawl doors to the warp (wire ropes) is one of the most dangerous moments, as these doors weigh several hundred kilograms. Other parts of the fishing gear are also too heavy to be handled without the use of derricks and winches while shooting the trawl (i.e., heavy gear and bobbings move freely around before being hoisted overboard).

The whole procedure of setting and hauling aboard the trawl, purse seine and nets is carried out using wire cables which pass across the working area often. The cables are at high tension, as there is often an extremely heavy pull from the fishing gear in a direction opposite of the forward motion of the fishing vessel itself. There is a great risk of getting entangled by or falling onto the fishing gear and thus being drawn overboard, or of falling overboard when laying out the fishing gear. There is a risk of crushing and trapping injuries to fingers, hands and arms, and the heavy gear may fall or roll and thus injure legs and feet.

Bleeding and gutting the fish are often done manually and take place on the deck or on a shelterdeck. The pitching and rolling of the vessels make injuries to the hands and fingers common from knife cuts or from pricks of fish bones and spines. Infections in wounds are frequent. Long-line and hand-line fishing involve the risk of wounds to fingers and hands from the hooks. As this type of fishing is becoming more and more automated it is becoming associated with dangers from line haulers and winches.

The method of managing fishing by limiting the amount caught from a restricted natural resource area also influences the injury rate. In some places pursuit quotas allocate to the vessels certain days when they are allowed to fish, and the fishers feel they have to go fishing at these times whatever the weather.

Fatal accidents

Fatal accidents at sea are easily studied through mortality registers, as accidents at sea are coded on the death certificates as water transport accidents according to the International Classification of Diseases, with an indication as to whether the injury was sustained while employed on board. Death rates from work-related fatal accidents among workers in the fishing industry are high, and higher than for many other occupational groups on shore. Table 1 shows the mortality rate per 100,000 for fatal accidents in different countries. The fatal injuries are traditionally classified as (1) individual accidents (i.e., individuals falling overboard, being swept overboard by heavy seas or being fatally injured by machinery) or (2) individuals lost as a result of vessel casualties (e.g., because of foundering, capsizing, missing vessels, explosions and fires). Both categories are related to the weather conditions. Accidents to individual crew members outnumber the others.

Table 1. Mortality figures on fatal injuries among fishermen as reported in studies from various countries

Country

Study period

Rates per 100,000

United Kingdom

1958–67

140–230

United Kingdom

1969

180

United Kingdom

1971–80

93

Canada

1975–83

45.8

New Zealand

1975–84

260

Australia

1982–84

143

Alaska

1980–88

414.6

Alaska

1991–92

200

California

1983

84.4

Denmark

1982–85

156

Iceland

1966–86

89.4

 

The safety of a vessel depends on its design, size and type, and on factors such as stability, freeboard, weather-tight integrity and structural protection against fire. Negligent navigation or errors of judgement may result in casualties to vessels, and the fatigue which follows long spells of duty may also play a role, as well as being an important cause of personal accidents.

Better safety records of more modern vessels may be due to the combined effects of improved human and technical efficiency. Training of personnel, proper use of flotation support apparatus, suitable clothing and the use of buoyant overalls may all increase the probability of rescue of persons in the event of an accident. More widespread use of other safety measures, including safety lines, helmets and safety shoes, may be needed in the fishing industry in general, as discussed elsewhere in this Encyclopaedia.

Non-fatal injuries

Non-fatal injuries are also quite common in the fishing industry (see table 2). The body regions of injured workers most frequently mentioned are the hands, lower limbs, head and neck and upper limbs, followed by the chest, spine and abdomen, in decreasing order of frequency. The most common types of traumas are open wounds, fractures, strains, sprains and contusions. Many non-fatal injuries may be serious, involving, for instance, amputation of fingers, hands, arms and legs as well as injuries to the head and neck. Infections, lacerations and minor traumas of the hands and fingers are quite frequent, and treatment with antibiotics is often recommended by the ship’s doctors in all cases.

Table 2. The most important jobs or places related to risk of injuries

Job or tasks

On board vessels injury

On shore injury

Setting and hauling trawl, purse seine and other fishing gear

Entangled in the fishing gear or wire cables, crushing injuries, fall overboard

 

Connecting trawl doors

Crushing injuries, fall overboard

 

Bleeding and gutting

Cuts from knives or machines,
musculoskeletal disorders

Cuts from knives or machines,
musculoskeletal disorders

Long-line and hand-line

Wounds from hooks, entangled in the line

 

Heavy lifts

Musculoskeletal disorders

Musculoskeletal disorders

Filleting

Cuts, amputations using knives or machines, musculoskeletal disorders

Cuts, amputations using knives or machines, musculoskeletal disorders

Trimming fillets

Cuts from knives, musculoskeletal disorders

Cuts from knives, musculoskeletal disorders

Work in confined spaces, loading and landing

Intoxication, asphyxia

Intoxication, asphyxia

 

Morbidity

Information on the general health of fishers and overviews of their illnesses are mainly obtained from two types of reports. One source is the case series compiled by ships’ doctors, and the other is the medical advice reports, which report on evacuations, hospitalizations and repatriations. Unfortunately, most if not all of these reports give only the numbers of patients and percentages.

The most frequently reported non-traumatic conditions leading to consultations and hospitalization arise as a result of dental conditions, gastro-intestinal illness, musculoskeletal conditions, psychiatric/neurological conditions, respiratory conditions, cardiological conditions and dermatological complaints. In one series reported by a ship’s doctor, psychiatric conditions were the most common reason for evacuating workers from trawlers on long-term fishing voyages, with injuries only coming in second place as a reason for rescuing fishers. In another series the most common illnesses which necessitated repatriation were cardiological and psychiatric conditions.

Occupational asthma

Occupational asthma is frequently found among workers in the fish industry. It is associated with several types of fish, but most commonly it is related to exposure to crustaceans and molluscs—for example, shrimp, crabs, shellfish and so on. The processing of fishmeal is also often related to asthma, as are similar processes, such as grinding shells (shrimp shells in particular).

Hearing loss

Excessive noise as a cause of decreased hearing acuity is well recognized among workers in the fish-processing industry. The machine room personnel on the vessels are at extreme risk, but so are those working with the older equipment in fish processing. Organized hearing conservation programmes are widely needed.

Suicide

In some studies on fishers and sailors from the merchant fleet, high death rates because of suicide have been reported. There is also an excess of deaths in the category where the doctors were not able to decide whether the injury was accidental or self- inflicted. There is a widespread belief that suicides in general are underreported, and this is rumoured to be even greater in the fishing industry. Psychiatric literature gives descriptions of calenture, a behavioural phenomenon where the predominant symptom is an irresistible impulse for sailors to jump into the sea from their vessels. The underlying causes for the risk for suicide have not been studied among fishermen particularly; however, consideration of the psychosocial situation of the workforce at sea, as discussed in another article in this chapter, seems a not unlikely place to start. There are indications that the suicide risk increases when the workers stop fishing and go ashore both for a short while or definitely.

Fatal poisoning and asphyxia

Fatal poisoning occurs in incidents of fire on board fishing vessels, and is related to inhalation of toxic smoke. There are also reports of fatal and non-fatal intoxication resulting from the leak of refrigerants or the use of chemicals for preserving shrimp or fish, and from toxic gases from the anaerobic decay of organic material in unventilated holds. The refrigerants concerned range from the highly toxic methyl chloride to ammonia. Some deaths have been attributed to exposure to sulphur dioxide in confined spaces, which is reminiscent of the incidents of silo-filler’s disease, where there is exposure to nitrogen oxides. Research has similarly shown that there are mixtures of toxic gases (i.e., carbon dioxide, ammonia, hydrogen sulphide and carbon monoxide), along with low partial pressure of oxygen in holds on board ship and on shore, which have resulted in casualties, both fatal and non-fatal, often related to industrial fish such as herring and capelin. In commercial fishing, there are some reports of intoxication when landing fish that have been related to trimethylamine and endotoxins causing symptoms resembling influenza, which may, however, lead to death. Attempts could be made to reduce these risks through improved education and alterations to equipment.

Skin diseases

Skin diseases affecting hands are common. These may be related to contact with fish proteins or to the use of rubber gloves. If gloves are not used, the hands are constantly wet and some workers may become sensitized. Thus most of the skin diseases are contact eczema, either allergic or non-allergic, and the conditions are often constantly present. Boils and abscesses are recurrent problems also affecting hands and fingers.

Mortality

Some studies, although not all, show low mortality from all causes among fishermen as compared to the general male population. This phenomenon of low mortality in a group of workers is called the “healthy worker effect”, referring to the consistent tendency for actively employed people to have more favourable mortality experience than the population at large. However, due to high mortality from accidents at sea, the results from many mortality studies on fishermen show high death rates for all causes.

The mortality from ischemic heart diseases is either elevated or decreased in studies on fishermen. Mortality from cerebrovascular diseases and respiratory diseases is average among fishermen.

Unknown causes

Mortality from unknown causes is higher among fishermen than other men in several studies. Unknown causes are special numbers in the International Classification of Diseases used when the doctor who issues the death certificate is not able to state any specific disease or injury as the cause of death. Sometimes deaths registered under the category of unknown causes are due to accidents in which the body was never found, and are most likely water transport accidents or suicides when the death occurs at sea. In any case an excess of deaths from unknown causes can be an indication, not only of a dangerous job, but also of a dangerous lifestyle.

Accidents occurring other than at sea

An excess of fatal traffic accidents, various poisonings and other accidents, suicide and homicide have been found among fishermen (Rafnsson and Gunnarsdóttir 1993). In this connection the hypothesis has been suggested that seamen are influenced by their dangerous occupation towards hazardous behaviour or a hazardous lifestyle. The fishermen themselves have suggested that they become unaccustomed to traffic, which could provide an explanation for the traffic accidents. Other suggestions have focused on the attempts of fishermen, returning from long voyages during which they have been away from family and friends, to catch up on their social life. Sometimes fishermen spend only a short time ashore (a day or two) between long voyages. The excess of deaths from accidents other than those at sea points to an unusual lifestyle.

Cancer

The International Agency for Research on Cancer (IARC), which among other things has a role in evaluating industries in respect to the potential cancer risks for their workers, has not included fishing or the fish-processing industry among those industrial branches showing clear signs of cancer risk. Several mortality and cancer morbidity studies discuss the cancer risk among fishermen (Hagmar et al. 1992; Rafnsson and Gunnarsdóttir 1994, 1995). Some of them have found an increased risk for different cancers among fishermen, and suggestions are often given as to possible causes for the cancer risks which involve both occupational and lifestyle factors. The cancers which will be discussed here are cancer of the lip, lung and stomach.

Cancer of the lip

Fishing has traditionally been related to lip cancer. Previously this was thought to be related to exposure to tars used to preserve the nets, since the workers had used their mouths as “third hands” when handling the nets. Currently the aetiology of lip cancer among fishermen is considered to be the joint effect of exposure to ultraviolet radiation during outdoor work and smoking.

Cancer of the lung

The studies on lung cancer are not in accord. Some studies have not found increased risk of lung cancer among fishermen. Studies of fishermen from Sweden showed less lung cancer than the reference population (Hagmar et al. 1992). In an Italian study the lung cancer risk was thought to be related to smoking and not to the occupation. Other studies on fishermen have found increased risk of lung cancer, and still others have not confirmed this. Without information on smoking habits it has been difficult to evaluate the role of smoking versus the occupational factors in the possible cases. There are indications of the need to study separately the different occupational groups on the fishing vessels, as engine room personnel have elevated risk for lung cancer, thought to be due to exposure to asbestos or polycyclic aromatic hydrocarbons. Further studies are thus needed to clarify the relation of lung cancer and fishing.

Cancer of the stomach

Many studies have found elevated risk of stomach cancer in fishermen. In the Swedish studies the risk of stomach cancer was thought to be related to high consumption of fatty fish contaminated with organochlorine compounds (Svenson et al. 1995). At present it is uncertain what role dietary, lifestyle and occupational factors play in the association of stomach cancer with fishing.

 

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