Preventing Chemical Accidents: Understanding MSDS’s & Assessing Chemical Hazards
How Do We Know When a Toxic Substance Really Causes Human Disease?
The most certain method of identifying cancer-causing substances is to observe whether they have caused cancer in people. Epidemiologists design studies that follow certain populations over time to observe whether a specific agent (e.g., arsenic or benzene) or exposure (e.g., sunlight or smoking) is likely to cause cancer. Environmental causes of cancer have frequently been noticed in the workplace first. This is because workers in certain occupations have higher exposures to particular chemicals and for longer periods of time than the general population. The International Agency for Research on Cancer (http://www.iarc.fr), an agency of the World Health Organization, classified certain occupations as associated with cancer-causing exposures because of the increased incidence of cancers in these settings. The graphs compare deaths in a population of 17,800 asbestos workers and 17,800 people in the general population from 1967 to 1986.