Occupational Safety and Health

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As long as humans have existed they have had to work. Initially, there was a need to hunt to catch food and have materials to make clothing. Generally, males would do the hunting and women would do the processing of the materials. Food would be preserved by drying, salting, or other methods for use over time; clothing would be made; and shelter would be fashioned from the hides of animals. When societies became more complex and humans changed into settled creatures, agriculture became a dominant force in their existence. As crops became cultivated and animals domesticated, there was still a need for essentially year-round labor, with both cultivation and processing activities being divided among the males and females of families, and this would generally include children as well. Only as societies became more complex did nonagricultural activities become possible, such as work from artisans fashioning useful household products, religious goods, and goods used for war or hunting. Eventually, societies were able to sustain other artisans who pursued writing, music, and visual arts such as painting.

Throughout recorded history, there have been references to work under a variety of conditions. The Old Testament includes rules about safe practices with regards to agriculture and how to treat workers. The Greeks and Romans used slaves, generally those captured in battle, to do both domestic work and to work in especially hazardous conditions, such as in mining. The writings of the ancients even discuss some early preventive measures, such as using inflated pig bladders to breathe into to avoid dusty atmospheres.

The first written discussions specifically directed toward matters of occupational safety and health were those of Paracelsus, in the fifteenth century. In the early eighteenth century, Bernadino Ramazzini wrote the first text on occupational medicine, De morbis artificium diatriba, and he is generally regarded as the "father of occupational medicine." Ramazzini wrote about the health hazards for dozens of occupations ranging from ditch diggers to tailors, from religious activities to those quite secular. In the United States, in the early twentieth century, Dr. Alice Hamilton became the first woman physician appointed to a faculty position at Harvard University, where she worked at the School of Public Health promoting safe and healthful work practices in the United States. She has been recognized as the leader of the occupational medicine movement in the United States, which came relatively late compared with that in Europe.

Except for hunting, agriculture is the most longstanding work activity. Even today, some 70 percent of the world's working population is engaged in agriculture. In sharp contrast, less than 2 percent of Americans continue to be engaged in agriculture; however, these small numbers, utilizing modern equipment, can feed and help clothe much of the rest of the population of the United States, and much of the world. By contrast, much of the agricultural work done in the rest of the world is still tied to direct human labor, sometimes assisted by animals, and somewhat more rarely by modern equipment. Farming continues to be an occupation associated with great risk.

Beginning in earnest in the eighteenth century, the Industrial Revolution of Europe led to large numbers of individuals settling in cities and working in factories. As more and more people worked in factories, and the hazards of factory work became known, regulations came into place regarding who could work, and under what conditions. Initially, there were no restrictions on ages or hours of work, but gradually child-labor laws, laws regulating the work of women, and mandated maximum hours of work were put in place. Today, in the United States, laws such as the Fair Labor Standards Act control child labor, to some extent.


Until about 1970, there were few federal regulations in the United States with regard to workplace safety and health issues. Each state had its own set of laws with regards to what were considered fair labor practices for workers, as well as a workers' compensation system for individuals that were injured. There was state-by-state enforcement of such regulations. In 1970, laws were passed establishing two government agencies: the National Institute for Occupational Safety and Health (NIOSH) within the U.S. Department of Health and Human Services (USDHHS), which was mandated to undertake research and prevention activities related to work; and the Occupational Safety and Health Administration (OSHA) within the Department of Labor, which was mandated to set national standards for workplace safety and health and to enforce such standards. Workers' compensation, however, has been left on a state-by-state basis, despite efforts toward federal standardization. Compared with Europe, workers' compensation legislation came much later in America, and is more varied.

Other regulations have to do with such issues as workplace drug testing and how such testing must be done. The Americans with Disabilities Act prohibits discrimination for those with handicaps and also requires that certain accommodations be made in the workplace for those who develop disabilities. There are no international standards that are universally utilized with regards to workplace safety and health, but such standards do exist for manufacturing production and quality-control issues regarding manufactured goods. One federal law specifically compensates for coalworker's pneumoconiosis, which is caused by the inhalation of coal dust.

The oversight of occupational safety and health is delegated to OSHA, but other agencies regulate what can leave workplaces by way of emissions (the Environmental Protection Agency), or as products (the Food and Drug Administration or the Consumer Product Safety Commission).

NIOSH once maintained a list of the "top ten" issues considered the most serious in the area of occupational safety and health. Included were occupational cancers, occupational lung disease, skin disorders, and similar problems. In 1996 a major overhaul of this approach was undertaken, and currently the governing construct for research carried out by NIOSH is the National Occupational Research Agenda, or NORA. Replacing the traditional top-ten list are twenty-one areas covering basic toxicology, human interactions in the workplace, emerging technologies, and psychological aspects of work in ways that are much more comprehensive than what had existed previously. It also evaluates combinations of exposures in the workplace, since workers are rarely exposed only to one material at a time, and it includes issues such as workplace organization to see how this impacts on occupational safety and health.

In regulating workplace-related issues, one must note the interactions with normal life events and exposures; and care must be taken to fully understand what is truly workplace-related, what is not, and where and when workplace exposures may have some role in the development of injuries or illnesses. Common life events such as stress, smoking, drug use, and other factors such as noise may interact with what goes on in the workplace.

Substance abuse is another serious workplace issue. There are rules regarding the testing of employees, either at the time of hire and/or during their employment. Certain federal regulations mandate that specific workers, like those in transportation, are required to be tested if there is an accident. Special certification is required as one aspect of drug-testing activities.

Those best equipped to understand occupationally related problems are physicians trained in occupational medicine, a branch of the field of preventive medicine, but in which there are few specialists. Although there are approximately 800,000 physicians in the United States, only about 10,000 practice occupational medicine on a fulltime or part-time basis, and of these, only about 20 percent have ever had formal training and certification as specialists in occupational medicine. Most occupational medicine is practiced by primarycare physicians who generally have little training in this field. Medical schools spend virtually no time, if any, on occupational medicine. NIOSH provides some small level of funding to train occupational physicians as well as occupational health nurses, safety specialists, and other related health personnel.


As the term "occupational safety and health" implies, there are two aspects to this field. One is the area of safety, which seeks to make workplaces safe for workers so that they do not suffer injuries. Poorly designed or laid-out workplaces or equipment may pose a serious hazard to workers, and more than 400,000 injuries occur at work each year. Separate from the concept of safety is that of occupational health, where the goal is to prevent the occurrence of illnesses among workers because of exposures at their place of work.

With regards to safety issues, the greatest number of injuries seen at work, most of which are preventable, involve hearing loss, musculoskeletal disorders, and cumulative trauma problems such as carpal tunnel syndrome.

Equipment-related injuries are a major source of difficulty, and motor-vehicle injuries, specifically, make up the largest number of fatalities related to the workplace. In addition, there are always thousands of cases of broken bones, materials getting into the eyes, burns, and similar injuries that occur each year. The nature of these problems will vary by work sector, age, gender, and other factors, but hundreds of thousands of individuals suffer from workplace-related injuries each year. Many of the injured go on to have a permanent disability that may threaten their livelihoods.

Other workers are at risk due to exposure to fumes and gases. Damage to lungs, or even death, can occur when entering confined spaces where oxygen may be reduced. This includes such diverse settings as grain silos, manure pits, or oil storage tanks. Vehicle exhausts are also known to cause harm or death.

A variety of professionals specialize in issues of occupational safety. For example, certified industrial hygienists are the most experienced at assessing workplaces and monitoring workers to see what kinds of exposures are actually taking place. With regard to safety issues, certified safety professionals constitute a group well qualified to assess safety at workplaces and to put in place safety programs for workers. Other occupational safety professionals include engineers who can make assessments in the workplace. Along with industrial hygienists, they can address such issues as ventilation or other protective measures.

As noted above, these are specialists in the field of occupational medicine who are best equipped to recognize and deal with the medical aspects of these problems. The specialty of occupational medicine requires college, medical school, and a minimum three-year period of specialized training. Among the areas that an occupational disease specialist must study are toxicology, epidemiology, organization of the workplace, regulations that control workplace exposures, as well as the diagnosis, treatment, and prevention of occupational problems.


Occupational diseases are illnesses that occur because of workplace exposures. Each organ system can have its own set of problems due to a wide variety of exposures.

Skin. The largest organ of the body is the skin, and a considerable number of diseases occur because of exposures of the skin to various agents. These diseases include dermatitis, sensitizations, interactions with drug or chemical exposures, and other difficulties. The skin may also be the route of entry of foreign matter into the body, such as occurs with many chemicals and some viruses, such as HIV (human immunodeficiency virus), which may enter through an accidental inoculation by needlesticks or vials of tainted blood breaking. Some chemicals dry out the skin and make it more likely that other substances may get in. There are barrier creams available to protect the skin, and protective clothing may be used to prevent skin burns, such as when welding.

Lungs. Another large organ of the body frequently affected by workplace exposures is the lungs. The lungs are directly connected to the outside, and materials taken into the lungs may potentially cause local, or even systemic, disease. Protecting the lungs are a variety of biological process that attempt to block or eliminate foreign substances. These include the hairs in the nasal passages; the mucociliary escalator that exists at the top of the respiratory tract; and macrophages, special cells found in the lungs and elsewhere in the body that gobble up foreign materials. Even though defenses efficiently protect the lungs, many types of occupational lung diseases can develop. Among the most important is occupational asthma, which involves asthma-like symptoms triggered by exposures at the workplace to chemicals, animal hair, or other factors. In addition, a wide variety of dusts causes diseases in the lung, characterized by scarring due to the formation of collagen, the major component of connective tissue. The pneumoconioses can result from exposure to materials such as asbestos, coal dust, silica, talc, or man-made materials such as fibrous glass products. Other substances can enter the lungs and cause disease, including a variety of heavy metals, and a wide variety of substances with the capacity to produce lung cancer and related disorders.

Cardiovascular System. A number of substances are known to cause heart disease. For example, cobalt salts will cause a cardiomyopathy a weakening of the heart muscle and its ability to pump blood. Other materials can cause changes in the electrical pattern of the heart, known as arrhythmias. Some materials, such as carbon disulfide, a material used in the manufacture of nylon, can cause premature blockage of the arteries in the heart.

Reproductive Organs. The reproductive organs of both men and women can be affected by workplace exposures. Among women, the problem is rarely one of sterility, but of difficulty in becoming pregnant, or having pregnancies characterized by birth defects. Some materials are thought to have estrogenic-like properties that block the normal reproductive cycle.

In men, exposure to lead or to some pesticides, such as dibromochloropropane, can lead to reduced fertility. Some men even become sterile following exposure to certain materials in the workplace. There are still significant questions of whether alterations in the male gene pattern from workplace exposures can be passed on to offspring.

Urinary Tract. Different exposures can cause disease in the various parts of the urinary tract, which consists of the kidney, the ureter (which carries materials from the kidney to the bladder), and the bladder. For example, a number of materials cause malfunction of the kidney, such as exposure to certain solvents that may damage the kidneys sufficiently so that dialysis is required to cleanse the blood of materials that are normally filtered out through the kidney. Certain occupations or exposures may lead to kidney cancer, such as working with printing inks.

Similarly, the bladder can be affected. Certain chemicals, such as beta-naphthalamine or benzidinebased clothing dyes, may cause bladder cancer. Cancer may also result from parasitic diseases, such as schistosomiasis, which may occur due to the parasites entering the body or agricultural workers.

Nervous System. A variety of substances can do damage to the nervous systemsome acutely, and some over time. Certain pesticides can have acute, and sometimes lethal, affects on the nervous system, while other exposures may take weeks, months, or years to develop into disease. Manganese found in welding rods can lead to the development of a clinical picture that looks very much like Parkinson's disease. Lead can also damage the nervous system, leading to drooping wrists and ankles. Hearing loss, due to damage to nerves in the ear, is a major workplace problem.

Hematologic System. The blood-forming organs can also be affected by exposures in the workplace. Some substances cause anemia, such as lead and arsine, and some solvents can completely shut off blood production. Certain agents, such as benzene and ionizing radiation, can produce leukemias.

Liver. A number of agents are known to damage the liver. Most significant are a wide variety of solvents, many of whose use has been curtailed over time. These solvents can produce both acute and chronic disruptions of the cellular architecture of the liver, as well as its function. Some of these agents are used directly, like carbon tetrachloride in dry cleaning, while other are made into other products such as rocket fuel, pesticides, munitions, and paints.

Infectious Agents. A wide variety of infectious agents are also relevant to the workplace. Health care personnel, for example, are at an especially high risk of developing tuberculosis, various forms of viral hepatitis, and HIV/AIDS (acquired immunodeficiency snydrome). The handling of animals or animal hides can produce a wide range of problems, including anthrax and allergic asthma.

Musculoskeletal System. Another set of problems being seen more frequently in the workplace affect the musculoskeletal system. Many muscles and joints in the body can be involved, including the shoulder, elbow, wrist, hip, knee, and ankle. Back injuries are a major problem; prevention approaches include learning proper lifting techniques, use of assist devices, and exercise. A field of study called "ergonomics" specifically evaluates the relationship between persons and machines, and looks to develop tools or methods of working that can minimize injury. Should injuries occur, a variety of professionals may become involved in caring for the patient, including physicians, physical therapists, occupational therapists, and other rehabilitative specialists.


One special concern is the development of a variety of cancers due to workplace exposures. Cancers can be caused by exposure to a wide range of substances from organic chemicals, metals, certain dusts and fibers, and to physical agents such as radiation.

Many organ systems in the body can be affected. Some substances are only known to produce one type of cancer, whereas some can produce many types of cancers in many organs of the body. For example, asbestos produces a wide range of cancers, including lung cancer; mesothelioma, a rare cancer affecting the lining of the lung, or the pleura; various gastrointestinal-tract cancers, including those of the stomach, colon, and rectum; kidney cancer, and cancer of the oropharynx. Radiation, in various forms, can initiate leukemias, lung cancer, and other cancers, depending on the nature of the source material and the dose. Arsenic, a metal, can cause skin cancer, lung cancer, and an otherwise rare cancer known as a hemangiosarcoma (cancer of the lining of blood vessels). Some fifty or more materials are known or highly suspected of producing a cancer in humans, and many others are still under study.

According to the concept of "sentinal cancers," exposure to certain materials may signal special problems in the workplace. For example, mesotheliomas are almost always tied to asbestos exposure, and hemangiosarcomas result from thorotrast, vinyl chloride, or arsenic.

Some basic principles apply to occupational exposures that can lead to cancer. Not everyone exposed to a particular carcinogenic substance will develop cancer, but the risk is elevated, often many times. The risk of developing a cancer is closely tied to the dose received. The "dose-response" concept means that as the dose goes higher, the risk also increases. This concept applies to many aspects of occupational toxicology, not just cancer.

There is also the phenomenon of latency. For human cancers tied to workplace exposures, the malignancy often appears after ten years, although some are more rapid, such as radiation-induced cancers or leukemias related to benzene. After twenty years, the rate of cancer development often increases, and many risks last over an entire lifetime even if exposure extended for a relatively brief period or stopped many years before.

Some materials, acting together, produce far more cancer that the substances do acting separately. This is called the "synergistic" or the "multiple factor" effect. The first described synergistic effect was that asbestos and cigarette smoking lead to far more lung cancer than either cause alone. Radiation and cigarette smoking have a similar combined effect.


A wide variety of organizations, in addition to governmental agencies, are involved in issues of workplace safety and health. In the United States, organizations that have an interest in this field are the American Public Health Association, the American College of Occupational and Environmental Medicine, the American College of Preventive Medicine, and the Society of Occupational and Environmental Health.

On the international level, a variety of organizations are concerned with these issues. These include the World Health Organization, the International Labor Office, and the Collegium Ramazzini.

All these groups are concerned about the development of injuries and diseases in workers, and they also have a major focus on the prevention of these problems.

Other groups active in the protection of workers include various labor organizations, such as individual labor unions and some overarching groups such as the AFL-CIO. Worker health protection makes up a large part of their mandate. These groups examine, among other issues, the transfers of hazardous exposures around the world. It is unfortunately still true that hazardous materials that are banned for use in the United States can, in some cases, continue to be manufactured in the United States for export to other countries. Among these chemicals are dibromochloropropane and DDT, with often tragic consequences associated with their use. Similarly, using certain materials that are highly hazardous and known to cause disease, such as asbestos, are now almost eliminated in the United States but are exported for manufacture and use elsewhere around the world. More than twenty countries have now banned the use of asbestos inside their country, and there is a growing worldwide movement to eliminate the use of this material since safer substitutes can be found.

What is dismaying is that as workplaces in the United States and other major industrialized countries become safer over time, the knowledge about the hazards and the measures to control hazards are not being exported to developing countries along with the hazardous materials. As the world becomes more globalized, the hazards faced by workers become the same all over the globe. It needs to be recognized on a international level that almost all occupational injury and disease are entirely preventable.

Arthur L. Frank

(see also: Asbestos; Benzene; Ergonomics; Fair Labor Standards Act; Hamilton, Alice; HIV/AIDS; Lead; National Institute for Occupational Safety and Health; Occupational Disease; Occupational Safety and Health Administration; Pesticides; Ramazzini, Bernardino; Risk Assessment, Risk Management; Toxicology )


National Institute of Occupational Safety and Health (1994). National Occupational Research Agenda Update. Washington, DC: U.S. Department of Health and Human Services.

(2000). Worker Health Chartbook, 2000. Washington, DC: Department of Health and Human Services.

Rom, W. (1998). Environmental and Occupational Medicine, 3rd edition. Philadelphia, PA: Lippencott-Raven.

Weeks, J. L.; Levy, B. S.; and Wagner, G. R. (1991). Preventing Occupational Disease and Injury. Washington, DC: American Public Health Association.

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Occupational Safety and Health