Most of the information on the health effects of exposure to asbestos have been derived from studies of workers exposed to asbestos in the course of their occupations. From these studies, it is known that asbestos fiber concentrations for such workers were many times higher than those encountered by the general public or people who live or work in buildings with asbestos containing materials. To be a significant health concern, asbestos fibers must be inhaled. As such, asbestos exposure is principally associated with following respiratory diseases.
- Asbestosis – a scarring (fibrosis) of the lung. The scarring impairs the elasticity of the lung tissue and hampers its ability to exchange gases.
- Pleural plaque– a fibrous thickening of the lining of the chest cavity.
- Mesothelioma – a cancer of the mesothelium (the lining of the chest and abdominal wall)
Increased incidence of non-respiratory diseases have been found in some epidemiological studies. Cancers of the larynx, esophagus, stomach, colon-rectum, kidney and pancreas have been found present in slightly higher than predicted levels.
Asbestos related diseases have a synergistic relationship with cigarette smoking. There is an increased risk of developing cancer from either smoking or an asbestos exposure. These two factors working together have a synergistic effect: a smoker exposed to asbestos is subject to an increased chance of developing cancer equal to the individual risk factors multiplied together.
Asbestos related diseases have very long latency periods. This is the length of time between an exposure that will result in a health effect, and the onset of symptoms related to the resulting health effect. The latency periods for asbestos related diseases range from 15-30 years for asbestosis up to 30-40 years for mesothelioma.
Asbestos related diseases conform to a dose-response relationship. That is, the greater the exposure to asbestos (in terms of airborne concentration of asbestos and length of time of exposure), the greater the incidence of asbestos related disease. Asbestos workers have the highest incidence of asbestos related diseases, significantly higher than people who live or work in buildings with asbestos containing materials.