EPA has announced the availability of final toxicological reviews which provide scientific support for the human health hazard and dose-response assessments of tetrachloroethylene (PERC) and tetrahydrofuran (THF) in connection with the prestigious Integrated Risk Information System (IRIS) database (which can be accessed via http://www.epa.gov/iris/index.html).

For PERC, the EPA has calculated a chronic inhalation reference concentration (RfC; the estimate of a daily human exposure that is likely to be without an appreciable risk of deleterious non-cancer effects during a lifetime) of 40 µg/m3 based on the neurotoxicological effects seen in exposed workers. The Agency has also developed a chronic oral reference dose (RfD) of 6 µg/kg bw/day, which involved extrapolation from the human inhalation data. Under the 2005 EPA guidelines for carcinogen risk assessment, PERC is deemed "likely to be carcinogenic to humans" by all routes of exposure.

US Environmental Protection Agency. National Center for Environmental Assessment (NCEA).

Toxicological review of tetrachloroethylene (perchloroethylene) (CAS No.127-18-4) in support of summary information on the Integrated Risk Information System (IRIS).

Final report dated February 2012

EPA/635/R-08/011F

http://www.epa.gov/iris/toxreviews/0106tr.pdf

http://www.epa.gov/iris/subst/0106.htm

 

 

For THF, the Agency has developed a chronic oral RfD of 0.9 mg/kg bw/day, based on the decreased pup body weight gain seen in a good-quality two-generation reproductive (oral) toxicity study in rats. In addition, they have established a chronic inhalation RfC of 2 mg/m3 based on central nervous system effects and liver toxicity seen in male mice. Under the 2005 EPA guidelines for carcinogen risk assessment, there was "suggestive evidence of carcinogenic potential to humans" by all routes of exposure.

US Environmental Protection Agency. National Center for Environmental Assessment (NCEA).

Toxicological review of tetrahydrofuran (CAS No. 109-99-9) in support of summary information on the Integrated Risk Information System (IRIS).

Final report dated February 2012

EPA/635/R-11/006F

http://www.epa.gov/iris/toxreviews/1023tr.pdf
http://www.epa.gov/iris/subst/1023.htm

 

For 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD), the EPA has recently revised the IRIS summary and developed a new oral RfD of 0.0000007 µg/kg bw/day. This extremely low RfD was based on decreased sperm count and motility seen in men exposed to TCDD between the ages of 1-9 years following the Seveso industrial accident in Italy in 1976. No inhalation RfC or cancer assessment is currently available on the IRIS website.

US Environmental Protection Agency. National Center for Environmental Assessment (NCEA).

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (CAS RN 1746-01-6); summary information on the Integrated Risk Information System (IRIS).

http://www.epa.gov/iris/subst/1024.htm

 

The above items were taken from the March 2012 issue of Toxicology and Regulatory News which is sent automatically to members of bibra (click here for more details).

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