We are reporting for your information the results of a pilot inhalation developmental toxicology study with hexafluoroacetone (HFA: CAS:684-16-2) which was conducted at our Haskell Laboratory. This pilot study was conducted in order to set exposure concentrations for the main developmental toxicology study which will be conducted in July of this year. Our pilot studies do not fully evaluate developmental toxicity potential because a small number of animals are used and full fetal examination is not performed. In the pilot study six pregnant female rats per group were exposed to 0, 0.1, 10, 30, or 60 ppm HFA in air for six hours a day, on days 7-16 of gestation. On day 22, females were sacrificed and the fetuses weighted, counted, and examined for externally visible malformations. Dams exposed to 60 ppm were sacrificed in extremis after two days of exposure due to the severe toxicity of the test material (Attachment 1). At 30 ppm, four dams were found dead during the course of exposures: the two which survived to the final sacrifice had totally resorbed their fetuses. At 10 ppm, all dams survived until sacrifice. No clinical or weight changes which were attributed to HFA exposure occurred in the dams. Even in the absence of material toxicity, four of those dams exposed to 10 ppm had total resorptions. Of the two remaining dams, one was found at sacrifice to have a litter of 13 resorptions and one live malformed pup. The other dam had 16 resorptions, one live malformed pup, and one live pup with a developmental variation. At both 0.1 and 0 pm, all six females/group displayed no material toxicity and no malformations were observed in the fetuses. Two studies reported in the literature indicate HFA can exhibit embryotoxicity in rats. HFA is produced and used in manufacturing operations at only one DuPont site and used in small quantities at several DuPont laboratories. Our corporate acceptable exposure limit is 0.1 ppm. Until the present study is finalized and we have
sufficient data to determine an acceptable exposure limit for the fetus, we will continue to exclude women of childbearing potential from the workplace. Therefore within the DuPont Company, there is no population at risk. We will submit the final report of our main inhalation developmental toxicity study to EPA as soon as it become available.