Methyl-tertiary-butyl-ether (MTBE) misclassified

Methyl-tertiary-butyl-ether (MTBE) was introduced into motor fuels in 1992 to reduce carbon monoxide automotive emissions in areas where the National Ambient Air Quality Standards for CO were exceeded. At a meeting of the National Toxicology Program's Board of Scientific Couns elors (2-3 December 1998), data were presented showing that exposure to MTB E caused increased incidence of liver tumors, renal adenomas, carcinomas an d interstitial cell adenomas of the testes in male, and lymphomas and leuke mia in female CD1 mice [National Toxicology Program, 1998]. Despite this ev idence, the NTP Board defeated a motion to list MTBE as "Reasonably anticip ated to be a human carcinogen" by a vote of 6 to 5. This decision directly contravenes rules and procedures previously established by NTP for assessin g carcinogenicity of chemical compounds. Good public health policy dictates that the NTP Board conduct another revie w of MTBE with proper consideration of the criteria that have been establis hed for listing agents as carcinogens. Millions of Americans who are expose d daily to this chemical deserve an unbiased evaluation of carcinogenic age nts being introduced into the environment. Am. J. Ind. Med. 39:505-508, 200 1. (C) 2001 Wiley-Liss, Inc.