It is important to understand these strengths, weaknesses, and limitations. Epidemiology Epidemiology, or the study of the occurrence of disease in people, is the most common method of determining a cause of cancer. This technique is easily accepted and certainly the most easily understood. Associating exposure to a chemical with a large number of people either dead or ill with an identified disease often can be very simple and straightforward. In fact, most health regulations today are based on epidemiological studies.
Epidemiological studies are very old and have a glorious and grand tradition.
The report, in 1775, by Sir Percival Pott of England, that chimney sweeps had a very high incidence of scrotal cancer may have been the first epidemiological study. However, there are many problems with epidemiology. Usually people do not know the chemicals they have been exposed to and the amount of their exposure. To produce a good epidemiological study it is critical to know chemical exposure and quantity, not only for the workers, but also for consumers of a product. Another major problem is that this method cannot detect small differences in the rates of common diseases.