Submarine Exposure Guidance Levels for Selected Hydrofluorocarbons: HFC-236fa, HFC-23,and HFC-404a (2000)
Chapter: Developmental Toxicity
sure concentrations well above the NOAEL can reach the target chemical concentrations in blood within min, and that exposure concentrations below the LOAEL can reach target chemical concentrations in blood if exposure continues long enough.
Subchronic Toxicity
Nakayama et al. (1992b, as cited in Kawano et al. 1995) exposed (whole body) rats (10 of each sex per group) to HFC-125 for 6 hr per day, 5 days per week for 4 weeks at concentrations of 0, 5,000, 15,600, or 50,000 ppm. In addition, 10 rats per sex were assigned to the control and high-exposure groups for assessment of a 2-week post-exposure recovery. Clinical observations, body weight, food consumption, clinical pathology, organ weight, and tissue histopathology were evaluated. Liver β-oxidation activity was also measured. There were no HFC-125-related adverse effects at any exposure concentration.
In another study using the same test concentrations as above (5,000, 15,600, and 50,000 ppm), groups of rats (20 per sex) were exposed for 13 weeks, and the same biological end points measured in the 4-week study were evaluated (Nakayama et al. 1993, as cited in Kawano et al. 1995). No adverse effects were observed.
Reproductive Toxicity
No reproductive toxicity studies of HFC-125 are currently available.
Developmental Toxicity
Two inhalation studies, one in rats and one in rabbits, were conducted to evaluate the developmental toxicity of HFC-125.
In the study with rats (Master et al. 1992, as cited in Kawano et al. 1995), groups of 25-29 pregnant rats were exposed (whole body) to HFC-125 at concentrations of 0, 5,000, 15,000, or 50,000 ppm for 6 hr per day on days 6-15 of gestation. The only signs of clinical maternal effects were observed in the group exposed at 50,000 ppm. The rats exhibited unsteady gait during exposure but not after. There were no significant differences between
