National Toxicology Program

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Public Health Service

National Toxicology Program; Call for Public Comments; Agents, Substances, Mixtures and Exposure Circumstances Proposed for Listing in or Removing from the Report on Carcinogens, Ninth Edition

The National Toxicology Program (NTP) announces its intent to re-review 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (CAS # 1746-01-6) for possible listing in the Report on Carcinogens, Ninth Edition as Known To Be A Human Carcinogen..

Background
This Report is a Congressionally-mandated listing of Known Human Carcinogens and Reasonably Anticipated Human Carcinogens and its preparation is delegated to the National Toxicology Program by the Secretary, Department of Health and Human Services (HHS). Section 301 (b) (4) of the Public Health Service Act, as amended, provides that the Secretary, (HHS), shall publish a report which contains a list of all substances (1) which either are known to be human carcinogens or may reasonably be anticipated to be human carcinogens; and (2) to which a significant number of persons residing in the United States (US) are exposed. The law 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.

2,3,7,8- Tetrachlorodibenzo-p-dioxin (TCDD) was reviewed in public session by the NTP Board of Scientific Counselors Subcommittee for the Report on Carcinogens on October 30 & 31, 1997. This review resulted in the Subcommittee's recommendation to upgrade the TCDD listing from Reasonably Anticipated to Be A Human Carcinogen to Known To Be A Human Carcinogen.

NTP announces a re-review of 2,3,7,8-tetrachlorodibenzo-p-dioxin and requests public comments
Following his review of the proceedings of that meeting, the NTP Director has determined that the October 30 & 31 public review of TCDD may not have been adequate and has directed that the nomination of TCDD for upgrading to a Known to be Human Carcinogen in the Report on Carcinogens be formally reviewed again by the NTP Board of Scientific Counselors Subcommittee for the Report on Carcinogens in December 1998. The TCDD background document provided to the NTP Board Subcommittee and the public comments and the summary minutes of the October 30 & 31 1997, review by the NTP Board Subcommittee are available upon request. The NTP wants to insure that all relevant information for TCDD pertaining to its epidemiology and the mechanism of tumor formation in humans and laboratory animals is adequately considered and solicits additional relevant information in support of or against the nomination to list TCDD as a Known to be Human Carcinogen in the Report on Carcinogens, Ninth Edition. In light of the decision to re-review TCDD, the deadline for public comments on dioxin will be extended until June 15, 1998 (see Federal Register: March 19, 1998 (Volume 63, Number 53, Page 13418). All comments received will be considered in the preparation of any additional information to supplement the original background document. Any new or supplementary information to be provided to the NTP Board Subcommittee members will be available to the public approximately one month prior to the December peer review meeting.

Requests for the background information described, comments, or questions should be directed to Dr. C. W. Jameson, National Toxicology Program, Report on Carcinogens, 79 Alexander Drive, Building 4401, P.O. Box 12233, Research Triangle Park, NC 27709; phone: (919) 541-4096, fax: (919) 541-2242, email: jameson@niehs.nih.gov.

Dated: April 8, 1998

____________________________
Kenneth Olden, Ph. D.
Director
National Toxicology Program

[Billing Code 4140-01-P]