Partially Vaporized Full Range Catalytic Reformed Naphtha: Subchronic and Developmental Toxicity Studies in Rats

Abstract

Both a subchronic study and a developmental toxicity screen were performed with full-range catalytically reformed naphtha (reformate), one of the refinery streams used to blend gasoline. Inhalation exposures of rats were done by partial vaporization of the reformate to produce vapors with a composition similar to the profile of relatively volatile compounds found in personnel samples from operators working around reformer units in refineries. In the subchronic study, groups of Sprague-Dawley rats (15/sex) were exposed for 13 wk to 0, 410, 1970, or 8050 mg/m³ of vapors. Following exposures, samples were taken for hematology, serum chemistry, number of spermatids, number and morphology of sperm, weights of 13 organs, and histopathology of 24 organs. Body weight and weights of liver and kidney were marginally affected in males of the high-concentration group. Developmental toxicity was assessed in pregnant Sprague-Dawley rats (11-12/group) exposed to 0, 2160, or 7800 mg/m³ of vapors on gestation days 6-19. Animals were sacrificed on gestation day 20. Maternal body weights, serum chemistry values, and organ weights were not affected by reformate vapor exposure. No adverse effects were observed for fetal parameters at the time of cesarean section (viability, body weight, external development) or subsequent fetal skeletal and visceral examinations. Overall, exposures of rats to high concentrations of the lighter fractions of reformate resulted in minimal toxicity.