Reproductive toxicity screen of trifluoroiodomethane (CF3I) in Sprague-Dawley rats

CF3I is being considered by the U.S. Air Force as a replacement for Halon 1 301 for fire-extinguishing requirements in unoccupied spaces. The purpose o f this study was to determine and evaluate the potential for CF3I to produc e reproductive toxicity and to provide additional information on the effect of CF3I exposure on the thyroid. Groups of 16 male and 16 female rats were exposed (6 h/day) to CF3I 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 CF3I 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-gen eration pups were not exposed to CF3I vapor. In parental animals, there wer e no clinical signs of toxicity except for a minimal decrease in mean body weight in female rats at 2.0% CF3I. At necropsy, gross findings, mean serum chemistry levels, mean hematology values, mean bone marrow micronuclei sco res, 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-elated microscopic tissue findings, including the thyroid organ. Analysis of repr oductive indices and parameters indicates CF3I is nor a reproductive toxica nt. Results of serum thyroid hormone levels (e.g., T-3, T-4, rT(3), and TSH ), showed concentration-related increaser in TSH, T-4, and rT(3). T-3 level s were decreased. First-generation pup survival and mean body weights were similar in all exposure groups, including the control. Exposure of 2.0% CF3 I vapor for approximately 14 wk produced minimal general toxicity and no re productive toxicity in Sprague-Dawley rats. On the basis of reproductive in dices and parameters, the NOAEL for this study is 2.0% CF3I.