We have now completed our initial review of the data contained in the two-year study of Fischer 344 rats fed acrylonitrile-containing drinking water for two years. There was no statistically significant increase in the incidence of any individual tumor or combination of tumors in either males or females exposed to 1 ppm. At 3 ppm, the incidence of squamous cell papillomas of the stomach was slightly elevated in males but not females. No other incidence of an individual or combination of tumors was significantly elevated. Based upon all of the information available from this study, it can be concluded that no biologically significant elevation in tumor induction occurred at exposure levels of 1 ppm or 3 ppm. Thus, the 'no effect' level, previously observed at 1 ppm on another animal species (Sprague-Dawley rats) in the two studies supplied to you July 28, 1980, has been demonstrated for a third time. In total, in the three studies we now have supplied to the FDA in this subject area, we have observed a 'no effect' level at 1 or 3 ppm in some 800 total rates, male and female.