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Those who work full time over a working lifetime will spend about 94,000 hours in the workplace. If that workplace is dusty or laden with chemicals or allergens, it has the potential to induce disease. The higher the exposures, the greater the likelihood of disease. For centuries scholars have recognized that the work environment plays a significant role in the occurrence of adverse human health effects. Early writings by Ulrich Ellenbog (1435 to 1499), Agricola (1494 to 1555), and Paracelsus (1492 to 1541) revealed the toxic nature of exposures in mining, smelting, and metallurgy. A systematic treatise by Ramazzini (1633 to 1714) described the hazards as they applied to workers in over 50 common trades including miners, chemists, tinsmiths, tanners, pharmacists, grain sifters, stonecutters, sewage workers, and even corpse bearers. Legislation to protect worker health began in England with the Factory Act of 1833 which established a factory inspectorate and limited child laborers 9 to 13 years old to a 48-hour work week and 14- to 18-year olds to a 68-hour work week.
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Today we continue to be concerned with occupational health and safety in a wide variety of work environments and child labor remains a concern worldwide. There are an estimated 151.6 million children between the ages of 5 and 17 engaged in child labor and half of them do hazardous work (ILO, 2017). Although occupational settings in developed countries are safer now than in the past, the levels of risk deemed acceptable have decreased while the recognition of the causal link of exposures to chronic diseases or diseases with long latencies has increased. As new hazards arise with the emergence of new technologies, we must be prepared to assess the risks and protect the health of workers. With increased globalization and rising prosperity in many middle-income countries, there exists a responsibility to extend health protections to workers in developing nations who too often bear the burden of high exposures to occupational toxicants.
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Occupational toxicology is the application of the principles and methodology of toxicology toward understanding and managing chemical and biological hazards encountered at work. The objective of the occupational toxicologist is primary prevention, that is to prevent adverse health effects in workers that could arise from exposures in their work environment. Because nonoccupational exposures can act as confounders or can increase the susceptibility of individual workers, occupational toxicologists must evaluate the entire spectrum of exposures experienced by the work force under consideration. Occupational toxicology is a discipline that draws on industrial hygiene, epidemiology, occupational medicine, and regulatory toxicology. The occupational toxicologist must have an intimate knowledge of the work environment and be able to recognize and prioritize exposure hazards. Because the work environment can present exposures to complex mixtures, the occupational toxicologist must also recognize those that are particularly hazardous when occurring in combination.
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It is often difficult to establish a causal link between a worker's illness and ...