Fluorine-containing monomers form the basis for production of a large number of commercially important polymers. Most of the polymerization occurs as gas-phase reactions, hence the hazards associated with the monomers arises primarily from inhalation. The chemicals covered in this review include bromotrifluoroethylene (BTFE), chlorotrifluoroethylene (CTFE), hexafluoroacetone (HFA), hexafluoroisobutylene (HFIB), hexafluoropropylene (HFP), perfluorobutylene (PFBE), tetrafluoroethylene (TFE), trichloropropene (TFP), vinyl fluoride (VF), and vinylidene fluoride (VF2). The amount of toxicologic information available on the compounds is relatively small and for certain of these the information consists is short-term or acute, hence the current need to make predictions of biologic activity based on analogy or chemical reactivity is great. In animal models and in man, these monomers may be absorbed into the body at varying rates and the metabolism ranges from extensive to little in a species, dose, and chemical specific fashion. The major toxicologic target of these materials is the kidney, and the degree of involvement depends greatly on the excretion patterns and metabolic profiles of the monomers. However, other target sites exist, such as the reproductive system for HFA, making the use of structure-activity relationships difficult.
Perfluorooctanoate (PFO) is a perfluorinated carboxylate that is widely distributed in the environment. A 2-year chronic study was conducted in rats fed either 30 or 300 ppm of ammonium perfluorooctanoate (APFO). To investigate the possible relationship of APFO exposure to proliferative mammary lesions, a Pathology Working Group (PWG) review of the original slides was performed. The consensus reached by the PWG was that the incidence of mammary-gland neoplasms was not affected by chronic dietary administration of APFO. Therefore, feeding female rats up to 300 ppm of APFO resulted in no increase in proliferative lesions of the mammary tissue.
Dimethyl sulfate (DMS; CAS No. 77-78) is a colorless, oily liquid which is used as a chemical intermediate and as a reactant in producing polyurethane resins. In this study, groups of pregnant Crl:CD BR rats were exposed, nose-only, to either 0.1, 0.7 or 1.5 ppm DMS by inhalation for 6 hr/day from Days 7 through 16 of gestation (day in which copulation plug was detected was designated Day 1G). A control group of pregnant rats was exposed simultaneously to air only. All female rats were euthanized on Day 22G and the fetuses were examined. A suppression of both food consumption and the rate of body weight gain was seen in the 0.7 and 1.5 ppm groups. No unusual clinical signs were seen in rats exposed to DMS. None of the reproductive parameters was altered in any of the groups and no statistically significant fetal effects were detected. DMS is not a developmental toxin in the rat following inhalation exposures up to 1.5 ppm during the period of major organogenesis.
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