Health Effects of Asbestos Exposure
Death Rates
The Occupational Safety and health Administration has declared that they are "aware of no instances in which exposure to a toxic substance has more clearly demonstrated detrimental health effects on humans than has asbestos exposure." By one count over 21 million men and women were occupationally exposed to asbestos between 1940 and 1980 alone.
Risk of asbestos related illness is Dose-Response related. That is, the greater the amount of exposure and the longer the time of exposure, the greater the risk of asbestos related cancers.
The following chart depicts the number of deaths per 1000 workers during a working career based upon the airborne levels of asbestos fiber to which the workers were exposed.
[Example: in a working environment of 2.0 fibers per cubic centimeter, 64 deaths per 1000 workers would be expected]
The graph clearly shows that the greater the exposure, the greater the number of deaths. Conversely, the lower the exposure, the fewer deaths.
As a matter of comparative interest, the original OSHA permissible exposure level from 1972 was 5.0 f/cc (which is clear off of the above chart), was then reduced to 2.0 f/cc in the mid '70's (64 deaths per 1000). Then in 1986 OHSA reduced the PEL from 2.0 to 0.2 f/cc and then recently to 0.1 f/cc. Even at the present PEL of 0.1 f/cc there are an estimated 3.2 to 3.7 asbestos related deaths per 1000 workers expected. Present EPA "clearance" levels following abatement work are 0.01 f/cc, 1/10th of the OSHA permissible exposure level.
It may be noted in the above chart that while the death rate decreases with reduced exposure, there is no level at which the death rate reaches zero (0.0).
Similarly, asbestos is present in the air in our atmosphere. There is no "zero" exposure. This is partly due to the fact that asbestos is a naturally occurring mineral, and partly due to man's usage (and disturbance) of the material.
Although the initial focus of inquiry was on the exposures associated with the manufacture of asbestos products (estimated over 3000 such building material products), after World War II the focus shifted to include exposure associated with product use. Research on short term occupational exposure and on workers with low cumulative exposures has confirmed that excess mortality can be expected at low occupational exposure levels.
