Reproductive toxicity screen of trifluoroiodomethane (CF(3)I) in Sprague-Dawley rats

CF(3)I is being considered by the U.S. Air Force as a replacement for Halon 1301 for fire-extinguishing requirements in unoccupied spaces. The purpose of this study was to determine and evaluate the potential for CF(3)I to produce reproductive toxicity and to provide additional information on the effect of CF(3)I exposure on the thyroid. Groups of 16 male and 16 female rats were exposed (6 h/day) to CF(3)I vapor at concentrations of 0 (control), 0.2, 0.7, and 2.0% using whole-body inhalation chambers. Prior to mating, rats were exposed to CF(3)I for 4 wk (5 days/wk). Exposures were 7 days/wk during the periods of mating (2 wk), gestation (3 wk), and lactation (3 wk). First-generation pups were not exposed to CF(3)I vapor. In parental animals, there were no clinical signs of toxicity except for a minimal decrease in mean body weight in female rats at 2.0% CF(3)I. At necropsy, gross findings, mean serum chemistry levels, mean hematology values, mean bone marrow micronuclei scores, and mean organ weights were similar for all exposure groups, including the air control group. Statistically significant differences did not show a pattern and/or were considered incidental. There were no treatment-related microscopic tissue findings, including the thyroid organ. Analysis of reproductive indices and parameters indicates CF(3)I is not a reproductive toxicant. Results of serum thyroid hormone levels (e.g., T(3), T(4), rT(3), and TSH), showed concentration-related increases in TSH, T(4), and rT(3). T(3) levels were decreased. First-generation pup survival and mean body weights were similar in all exposure groups, including the control. Exposure of 2.0% CF(3)I vapor for approximately 14 wk produced minimal general toxicity and no reproductive toxicity in Sprague-Dawley rats. On the basis of reproductive indices and parameters, the NOAEL for this study is 2.0% CF(3)I.