EPA announced last month that it plans to address the four draft Integrated Risk Information System (IRIS) assessments that were placed on hold in June 2010, when EPA announced it would review of some of the underlying studies relied on in the assessments. The four assessments are methanol, methyl tertiary-butyl ether (MTBE), ethyl tertiary-butyl ether (ETBE) and acrylonitrile.
EPA held the assessments because of a report written by the National Toxicology Program (NTP), which pointed out differences in opinion between NTP scientists and the Ramazzini Institute, a lab in Italy that performed several cancer testing studies.
EPA and National Institute of Environmental Health Sciences are jointly sponsoring an independent Pathology Working Group (PWG) review, in cooperation with the Ramazzini Institute, of the Ramazzini studies of MTBE, ETBE, and acrylonitrile. EPA will continue with the IRIS assessments for these three chemicals while the PWG review is conducted. EPA has put the methanol study on hold, however, pending the outcome of the PWG review.