NIEHS: TCDD Listed as 'Known Human Carcinogen' in US 9th Report On Carcinogens

Gary Greenberg Gary.Greenberg at Duke.edu
Sun Jan 21 00:24:29 EST 2001

FOR RELEASE JAN. 19, 2001 
NIEHS PR #01-04 
NIEHS CONTACT: Bill Grigg (301) 402-3378 
grigg at niehs.nih.gov 

NTP Public Liaison Office, (919) 541-0530

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

NTP is headquartered at the NIEHS in Research Triangle Park, N.C.

# # # #

The URL for this press release is:

Gary N. Greenberg, MD MPH    Sysop / Moderator Occ-Env-Med-L MailList
gary.greenberg at duke.edu     Duke Occupat, Environ, Int & Fam Medicine
OEM-L Maillist Website:                      http://occhealthnews.com


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