National Toxicology Program

The meeting of the NTP Board of Scientific Counselors Technical Reports Review Subcommittee that was tentatively scheduled for November 5 and 6, 2003, has been postponed. The meeting will be rescheduled for the winter 2004.

The toxicology and carcinogenicity studies that will be peer reviewed are listed below and include four dioxin/dioxin-like compounds, including dioxin, a polychlorinated biphenyl, a polychlorinated furan and a mixture of these compounds.

• 3,3',4,4',5-Pentachlorobiphenyl (PCB126) /57465-28-8
• 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) /1746-01-6
• 2,3,4,7,8-Pentachlorodibenzo-furan (PeCDF) /57117-31-4
• A mixture of PCB 126, TCDD, and PeCDF
• Malachite Green /569-64-2 and Leucomalachite Green /129-73-7
• Anthraquinone /84-65-1 (The draft NTP Technical Report on Anthraquinone was previously reviewed in May 1999. Subsequent to that peer review, the anthraquinone tested was found to contain a 0.1% contaminant. As a result, the NTP conducted additional mutagenicity and metabolism studies and the findings from those studies are being incorporated into a revised draft technical report. The Subcommittee will evaluate the results from the follow-up studies, use that information to re-examine the carcinogenicity findings from the 2-year studies and make a recommendation on the carcinogenicity of the anthraquinone tested.)

The studies on the dioxin/dioxin-like compounds were designed to evaluate the relative toxic and carcinogenic effects between the individual chemicals and the mixture. Due to the need to ensure a consistent pathological diagnostic approach across all four studies, an expanded evaluation of the liver pathology data is being conducted. Because of the expanded pathology review, the public comment period for these studies would have been insufficient if the meeting were held on the original dates.

The rescheduled Subcommittee meeting will be held in Research Triangle Park, NC. Once plans for the meeting are finalized, the NTP will publicize details about the meeting's date and location, deadlines for public comments and how to gain access to copies of the draft reports. This information will be made available through the Federal Register, the NTP's website (http://ntp.niehs.nih.gov/ntp), its list-server (an electronic notification service), and its quarterly newsletter the NTP Update.