Last Comment Sought On Agents Proposed For Report On Carcinogens; A Final For Data On Saccharin, And A Re-Review Of Dioxin Announced

"Final" comment on a proposal to remove saccharin from the Report onCarcinogens was also sought. In an associated Federal Register notice, the NTPsaid it is also re-reviewing dioxin for procedural reasons.

NTP said in one notice it is "especially interested in obtaining additionalrelevant scientific information in support of or against the petition to delistsaccharin" because the three reviews split in their recommendations. Twoscientific reviews favored removing saccharin from the Report but an October30-31 advisory panel -- the NTP Board of Scientific Counselors Subcommittee forthe Report on Carcinogens -- recommended by a narrow margin that the sweetenercontinue to be listed as an "anticipated" carcinogen.

The NTP, which is headquartered at the National Institute of EnvironmentalHealth Sciences in Research Triangle Park, N.C., particularly asked informationon:

-- The adequacy of existing epidemiology data, particularly as itrelates to reported increased incidences of bladder tumor formation in certainsubpopulations.
-- The mechanism of urinary bladder tumor formation in male rats as itrelates to other test species and to humans.

Final comment was also requested for additional substances to be listedas "reasonably anticipated to be a human carcinogen":

-- Chloroprene, a component of adhesives in food packaging;phenolphthalein, a cathartic recently removed from popular nonprescriptionlaxatives following NIEHS studies; tetrafluoroethylene, used in the productionof Teflon, and trichloroethylene, a solvent.

NTP said that the NTP Board subcommittee's re-review of dioxin need notdelay its listing in the ninth Report on Carcinogens, which is planned for nextyear. Kenneth Olden, Ph.D., director of the NTP and the NIEHS, said he has noargument with the recommendation to upgrade dioxin from "reasonably anticipated"to "known human carcinogen" but wanted to make sure the review crossed every "t"and dotted every "i" in this first set of actions following recent changes inthe criteria and procedures for listing agents in the Report.

A press release on the advisory council's review of these substances may beobtained at http://www.niehs.nih.gov under news and publications or by telephoningthe contact listed at the beginning of this release. The FR notices are onpage 13418 (March 19) and page 18435 (April 15).

Comment should be sent to Dr. C. W. Jameson, NTP Report on Carcinogens,EC-14, P.O. Box 12233, Research Triangle Park, NC 27709, by May 19, 1998, or, in thecase of dioxin (TCDD) June 15.