TCDD - Dioxin -- is Listed as 'Known Human Carcinogen' in
Federal Government's Ninth Report On Carcinogens
The National
Toxicology Program announced today the publication of an addendum
to its Ninth
Report on Carcinogens that adds
2,3,7,8-tetrachlorodibenzo-p-dioxin, also known as TCDD or Dioxin,
to the list of substances "known
to be human carcinogens."
Kenneth
Olden, Ph.D., Director of the National Institute of
Environmental Health Sciences and the National Toxicology
Program, which has the responsibility for preparation of this
report, said that publication of this addendum follows the recent
ruling by the U.S. Court of Appeals for the District of Columbia
Circuit dismissing a request for an injunction to prevent the
listing of TCDD as a "known human carcinogen" pending appeal of the
district court's decision upholding the listing.
The change in the listing of TCDD from the "reasonably
anticipated" to the "known to be a human carcinogen" category had
been planned to occur in the Ninth Report, but the designation was
delayed by litigation. The plaintiffs in the lawsuit claim that the
Department of Health and Human
Services and National Toxicology
Program had improperly applied the Report on Carcinogens'
listing criteria in listing TCDD as a "known human carcinogen." The
Ninth Report was published last May 15 with TCDD listed as a
"reasonably anticipated" human carcinogen but with a statement
included indicating an addendum may be published following the
Court's ruling on the litigation.
The National Toxicology Program's listing of TCDD in the " known"
category is based on sufficient evidence of carcinogenicity from
studies in humans, involving a combination of epidemiological and
mechanistic information which indicates a causal relationship
between exposure to TCDD and human cancer.
TCDD is not deliberately produced today but has been found as a
contaminant in some herbicides and pesticides and is formed as an
inadvertent by-product of incineration of waste. TCDD levels in
Americans have declined in recent years as a result of environmental
controls but is still widely detected in the environment and can be
found in very small amounts in the general population. The Report on
Carcinogens is a cancer health hazard identification document that
discusses substances that may pose a carcinogenic hazard to human
health. The report does not present quantitative assessments of
carcinogenic risk, an assessment that defines the conditions under
which the hazard may be unacceptable.
The listing of substances in the report, therefore, does not
establish that such substances present carcinogenic risks to
individuals in their daily lives. Such formal risk assessments are
the purview of the appropriate Federal, State, and local health
regulatory and research agencies. Both the Environmental Protection
Agency and the Food and
Drug Administration have quantitative assessments of
dioxin's cancer risks.
The Report on Carcinogens is a Congressionally mandated listing
of known and reasonably anticipated human carcinogens. Its
preparation is delegated to the National Toxicology Program, which
is headquartered at the National Institute of Environmental Health
Sciences, by the Secretary, Department of Health and Human Services.
Section 301(b)(4) of the Public Health Service Act, as amended,
provides that the Secretary, Department of Health and Human
Services shall publish a report and also states that the
reports should provide available information on the nature of
exposures, the estimated number of persons exposed and the extent to
which the implementation of Federal regulations decreases the risk
to public health from exposure to these chemicals. The revised Ninth
Report that contains all addendum materials is available on the
Internet from the National Toxicology Program's web page at http://ntp-server.niehs.nih.gov/NewHomeRoc/AboutRoC.html
NTP is headquartered at the NIEHS in Research Triangle Park,
N.C.
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The URL for this press release is:
http://www.niehs.nih.gov/oc/news/dioxadd.htm
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