Epidemiology” is the study and analysis of the dispensation, order, frequency and affective factors of health and disease conditions in specific occupants and “Occupational Epidemiology” is its branch that deals with explorations of workers and the workplace issues. Thus it is an exposure-accustomed discipline with coupling to both epidemiology and occupational health.

Occupational Epidemiology includes studies to examine health issues in workers, and their threatening liaison with workplace environment related to various factors like exposure to dust, noise, chemicals, heat, or radiation and maintenance problems. It is a pivotal aspect of worker’s health, and helps in taking decisions and planning safe working practices by recognizing risk factors and is ready for preventive healthcare measures.  

Objectives Of Occupational Epidemiology

  • Prevention through exploring the consequences of workplace exposures on employee’s health.

The public health always is the primary concern of epidemiological research hence they can be immediately implementable. All research in the field of occupational health and safety should serve disease and injury preventive purposes

  • To use conclusions from specific background to minimise or avoid hazards in the large occupancy.

Besides providing information on the health effects of exposures in the workplace, the results from occupational epidemiology studies also helps in the estimation of risk of similar exposures.

  • Awakening about clinical observation and of the attention to the circumstances surrounding the occurrence of disease.  This is preferable to identify and describe many of the occupational diseases that can be later studied by occupational physicians and epidemiologists.


Categories Of Occupational Epidemiologic Studies 

There are two categories: Experimental and Observational

Experimental Studies

In an experimental study, the epidemiologist determines through a controlled process the exposure for each individual (clinical trial) or community (community trial), and then tracks the individuals or communities over time to detect the effects of the exposure.

Observational Studies

In an observational study, the epidemiologist simply observes the exposure and disease status of each study participant. 

The most common types of observational studies are: 

Cohort studies 

Case-control studies

Cross-sectional studies


5 W’s Of Epidemiology


Occupational Epidemiology stresses on the 5 W’s:

  1. diagnosis or health event (what)
  2.  person (who)
  3.  place (where)
  4.  time (when)
  5.  Causes, risk factors, and modes of transmission (why/how).


An epidemiologists has to ask many questions to the patients

What he is suffering?  For what reason?  For how many days? What he eats? and What are his bowel movements?

To all these questions they should add:

 ‘‘What work does he do?”



Elements Of An Epidemiologic Study

  • Identifying Study Populations

 It is necessary that the population, which is to be considered should be representative of the relative population and that it be large enough to ensure adequate statistical data.

  • Sample Size

Sample-size calculations are based on the expected magnitude of the difference between the exposed and unexposed groups.  Sufficient follow-up time is also important. Latency, follow-up, and other factors should be taken into consideration in calculating sample size.

  • Monitoring

Various methods are available for assessing individual 

Bio monitoring
Personal Monitoring
Environmental Monitoring


  • Comparison-Group Issues

 Comparison groups should be sampled and surveyed in the same way at the same time and using the same methods. The report should include information on potential confounding factors including education, sex, and other correlates of health status in both the study and comparison groups.

  • Exposure Assessment

Direct measurements of exposure at the individual level are not always easily available. Such information may be obtained from other sources, such as questionnaires on self-reported exposure information, and workplace surrounding monitoring.

  • Using Work History To Assess Exposure

Modelling cumulative exposure on the basis of a worker’s job history and the level of exposure is proved a helpful approach to assessing exposure in occupational epidemiologic studies.  Employment records can be used to define the amount of time that each worker spent in each job and the worker’s overall exposure in worksites over the course of employment.

  • The Strength Of The Evidence

Accurate exposure assessment and consequences can be used to assess exposure and to reach conclusions about the likely adverse health outcomes.


  • Bias And Perplex In Exposure Assessment

An Occupational Epidemiology should use to control perplexes and bias reasonably in exposure and assessments. Bias might cause deviation from the true value to observed value, and can weaken, exaggerate or reverse its direction for an association.


Issues In Occupational Epidemiology

The core of Occupational Epidemiology is conviction of an individual’s work life exposure experience.

  • An epidemiological study depends on the quality and extent of available exposure data. 

The occupational epidemiologist must be accurately determining the health effects among a well-defined and intelligible group of workers. So that any occupational exposure effects that are established from the study can be imputed to the occupational exposure rather than to other known causes. 

  • The epidemiological method is depend on available records —questionnaires, job titles or other substitutes of exposure; this makes the interpretation of their findings comparatively lucid.


  • Metabolic activation or inactivation of hazardous / carcinogenic substances varies considerably in human populations. Such findings may strongly affect regulatory decisions that focus the risk assessment process on the most susceptible prospects.



Specific ethical aspects associated to the safety of workers and of the occupants need identification:

  • Epidemiological studies in occupational settings should not be delayed to implement preventive measures in the workplace.
  • Occupational epidemiology refers to situations of exposure. This implies a commitment to effective prevention and to the immediate transmission of information to workers and the management.
  • Study reveals health hazards and provides the knowledge for preventive action.
  • Intimation to workers of the results of epidemiological studies is both an ethical and methodological safety issue in risk communication.
  • Highest priority should be given to research in evaluating the potential impact and effectiveness.


Occupational Epidemiology has been a sort of “Black Box” because it has studied the relationship between exposure and disease, the two rearwards of the causal chain.


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