"The dams were exposed to the test substance or clean air (control) by the whole-body inhalation route for 6 h/day (approximately 8.00 a.m. to 2.00 p.m.) from day 6 through 19 p.c. and from day 5 through 21 post partum (p.p., day of birth = day 1 p.p.). During this time, pups remained in their cages and were not exposed together with their lactating dams.

Exposure of the Animals

The exposure of animals to the test substance was performed in whole body inhalation chambers (6 m3). The exposure chamber was operated with a dynamic airflow sufficient to ensure an adequate oxygen content and an evenly distributed exposure atmosphere (air change 15 times/h). Flow rates were monitored continuously using flow meters and recorded at 15-min intervals throughout the exposure period. The temperature and relative humidity within the exposure chamber were maintained at 21– 27°C and 30–70%, and values were recorded at 15-min intervals. The exposure conditions were monitored by physical and chemical methods. The nominal concentration was calculated by mass transfer of test substance flow rates. The actual concentration of the test substance in the exposure chamber was measured using a flame ionization detector (FID). Values were recorded every 15 min. The FID was calibrated by independent gas chromatography (GC) measurements. During the study the exposure concentration was independently analyzed by GC twice in 1 wk and once every 2 wk thereafter by sampling for 15 min with 1-L Tedlar sample bags (DuPont). The analyses were carried out using a Hewlett Packard model 5890 series II with FID. The samples were injected into a split/splitless injector using a gas-tight syringe. Quantification was performed using the external standard method. Standard samples were prepared in 10-L Tedlar sample bags.The following gas chromatographic conditions were applied: column, PORAPLOT Q, 25 m × 0.32 mm with particle trap (2.5 m), 10-μm-thick bonded phase on fused silica; carrier gas, helium; column head pressure, 10 psi; temperatures, oven 100°C (1 min), 100–200°C (10°C/min), 200°C (2 min); detector 250°C; injector 100°C.

Fostering and Cross-Fostering of the Offspring

Pregnant and/or lactating dams were exposed to either clean air (control)or 1000 ppm HCFC-123. All pups of groups 01–04 were cross-fostered to new dams within the first 2 days after birth according to the groups mentioned in Table 1. Pup groups 05–06 (extra groups for investigations of the milk) and 07 (production of standard litters for the determination of milk production) were reared by their natural dams."

F1 Male and Female Sprague-Dawley Rats (HCFC-123/HCFC-123)