Reproductive Toxicity Screen of Trifluoroiodomethane (CF31) in Sprague-Dawley Rats

CF3I 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 CF3I to produce 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 (6hr/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 weeks (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 CF3I 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% CF3I. At necropsy, gross findings, mean serum chemistry levels, mean hematology values mean bone narrow micronuclei scores, and mean organ weights were similar for all exposure groups, including the air control group. Statistically significant differences were considered incidental. There were no treatment-related histopathologic tissue findings, including the thyroid organ. Analysis of reproductive indices and parameters indicate CF3I is not a reproductive toxicant Results of serum thyroid hormone levels (e.g., T3, T4, rT3, and TSH), indicated concentration-related increases in TSH, T4, and rT3. T3 levels were decreased. First generation pup survival and mean body weights were similar in all exposure groups, including the control. Exposure of 2.0% CF3I vapor for approximately 14 weeks produced minimal general toxicity and no reproductive toxicity in Sprague-Dawley rats. On the basis of serum TSH concentrations, the no-observable-effect-level (NOEL) is 0.7% CF3I.