Occupational epidemiology

Occupational epidemiology is one of the sub-disciplines of epidemiology that focus on investigations on workers and the workplace.[1][2] Occupational epidemiologic studies examine a variety of health outcomes among workers and their potential association with a variety of conditions in the workplace (such as noise, chemicals, heat, radiation, etc.) or work organization (schedules, etc.). The need for evidence to inform occupational safety regulations, workers' compensation programs, and federal safety legislation constituted part of the motivation for the development of public health policy, occupational epidemiology methods, surveillance mechanisms and the delineation of the scope of this area of knowledge.[3] Occupational epidemiological research can inform risk assessments; development of standards and other risk management activities; and estimates of the co-benefits and co-harms of policies designed to reduce risk factors or conditions that can affect human health. Occupational epidemiology methods are common to methods used in environmental epidemiology.

History

Occupational hazards have long been recognized. Hippocrates recommended other physicians consider the patients' environmental, lifestyle, and vocational backgrounds when diagnosing and treating disease. Bernardino Ramazzini, acknowledged as the father of occupational medicine outlined many occupational diseases in his book De Morbis Artificum, in 1700. Since then, the development of occupational epidemiology evolved out of numerous cases of widespread, diseases, common among groups of workers.[4]

Premature mortality was reported among miners in the Erz Mountains on the border of Germany and the former Czechloslovakia as early as the 16th century. Then called miners' disease it was subsequently determined to be pneumoconiosis. In 1879, Hessing and Hartung recognized that underground miners were dying of respiratory disease at an abnormal rate. In the 1930's, studies uncovered the association of miners' deaths and lung cancer and nonmalignant respiratory diseases. Epidemiologic studies since have provided evidence of an association between radon exposure and lung cancer. The need for the development of occupational epidemiology came from many similar cases of case reporting and studying, like cancer among chimney sweeps, asbestos related diseases, and the variety of occupational diseases found among factory workers in the early 1900's. Occupational health risks were initially observed by case series reports of apparent disease excesses or clusters.[4]

Although the case series approach provided a good indicator of occupational hazards, they are not adequate on their own to assess a wide spectrum of health outcomes that may not be closely related to workplace exposure. The development of retrospective, cohort design allowed for a more comprehensive study of the cases. Desire to improve the cost-efficiency of studies led to the use of case-control studies. Other methods later used in occupational epidemiology include cross-sectional and longitudinal studies.[4]

Types of studies

Case series

Typically occupational epidemiological investigations begin with the observation of an unusual number of cases of disease among a group of workers. When the investigation does not go further than what is referred to as identifying a disease cluster, the study is referred to as a case series report.[4]

Cohort studies

In a cohort design study, a population, or cohort, of workers is compared to a control group that was not exposed to the workplace hazards being investigated. This type of study is the most accepted in the scientific community because it most closely follows experimental strategy and observes the entire population rather than a sample. In a prospective cohort study, the group examined at the time of the study is compared to a follow up with the same group in the future. The historical cohort study design begins with defining a cohort at a time in the past and following the cohort over historical time.[4][5]

Case-control studies

Case-control studies compare the past exposure of cases with the disease to the past exposure of cases that did not have the disease. Because cohort studies require the entire population, case-control studies are a more cost-effective approach, using only the sample of workers with the disease to compare to a control.[4][5]

Cross-sectional studies

A typical cross-sectional study involves the comparison of varying degrees of exposure and the prevalence of disease, symptoms, or physiological status. The main advantage of cross-sectional studies is that they allow collection of data on conditions which would not be recorded normally because other study designs focus on severe states of disease. This is also the biggest shortcoming of this study type because by using prevalence rather than incidence it cannot be used to make a causal inference.[4][5]

Application

By contributing to reduction in exposure, occupational epidemiology helps reduce health risks among workers. Using occupational epidemiological methods can also have benefits for society at large. For example, recommendations for exposure limits to benzene developed by the Expert Panel on Air Quality Standards were based on occupational epidemiology.[5]

Using meta-analysis, many occupational epidemiology studies can be synthesized in order to help set occupational exposure limits and make other kinds of policy decisions. This can also can be applied in health risk assessments, which is a method of predicting health risk based on hypothetical exposure conditions.[4]

References

  1. ↑ "Occupational Epidemiology". U.S. Occupational Safety and Health Administration. Retrieved 2016-06-13.
  2. ↑ Checkoway, Harvey; Pearce, Neil; Kriebel, David (2004). Research Methods in Occupational Epidemiology. New York, NY: Oxford University Press. ISBN 0-19-509242-2.
  3. ↑ Halperin, William; Howard, John (2011-10-07). "Occupational Epidemiology and the National Institute for Occupational Safety and Health". Morbidity and Mortality Weekly Report. U.S. Centers for Disease Control and Prevention. 60: 97–103.
  4. 1 2 3 4 5 6 7 8 Checkoway, Harvey; Pearce, Neil; Crawford-Brown, Douglas J. (1989). Research methods in occupational epidemiology. New York: Oxford University Press. pp. 5–8, 59, 61, 66, 72, 331. ISBN 9780195092424. OCLC 610965808.
  5. 1 2 3 4 Agius, Raymond. "Occupational Epidemiology". Retrieved 2017-07-30.
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