Occupational Cancer and the National Institute for Occupational Safety and Health (NIOSH) Carcinogen Policy

In the 21st century, occupational cancer is still a significant cause of
morbidity, mortality, and societal burden. While the number of current workers
at risk of occupational cancer is not known precisely, the number of workers
exposed to OSHA regulated carcinogens is still in the millions and the size of
the population with past exposure is in the tens of millions. Estimates of the
fraction of cancers attributable to occupation vary. At least 4% (24,000) of
the approximate 600,000 deaths from cancer each year in the United States is
thought to be the result of exposures in the workplace [Ward et al. 2003]. It
is likely that this 4% is an underestimate. The calculation of this
attributable fraction was only conducted on a few carcinogens and cancer sites.
Moreover, the role of work and occupational exposures of cancers in women has
not been widely studied which may contribute to the underestimate. Other
estimates of cancer mortality attributable to workplace exposures range as high
as 10%. If the 4% estimate for deaths is the same for cancer morbidity, an
estimated 48,000 new cases of cancer each year have occupational causes. This
is an important contribution to the human cancer burden, exceeded only by the
contribution of cigarette smoking and diet [P. Schulte and T. Schnorr,
Presentation to the President's Cancer Panel 2008)."

The National Institute for Occupational Safety and Health (NIOSH) assessments
of workplace carcinogens and the setting of NIOSH Recommended Exposure Limits
(RELs) have been important tools in addressing the burden of occupational
cancer. Historically, in 1976, to address the growing perception of an
occupational cancer burden, NIOSH specified a policy to be used to classify
substances as carcinogens and to develop RELs which allowed for "no detectable
exposure levels for proven carcinogenic substances" [Fairchild 1976]. In 1995,
NIOSH revised this policy to include advances in science and approaches in risk
assessment and risk management (
This revised policy states that "NIOSH recommended exposure limits (RELs) will
be based on risk evaluations using human or animal health effects data, and on
an assessment of what levels can be feasibly achieved by engineering controls
and measured by analytical techniques. To the extent feasible, NIOSH will
project not only a no-effect exposure, but also exposure levels at which there
may be residual risks." This policy applies to all workplace hazards, including
carcinogens, and is responsive to Section 20(a)(3) of the Occupational Safety
and Health Act of 1970, which charges NIOSH to "…describe exposure levels that
are safe for various periods of employments, including but not limited to the
exposure levels at which no employee will suffer impaired health or functional
capacities or diminished life expectancy as a result of his work experience.

More info - Source: National Institute for Occupational Safety and Health (NIOSH)