“Analytical Determination of HFC 245/a in Air

For all rodent inhalation toxicity studies, calibration standards were prepared by injecting known amounts of HFC 245fa into a known volume of air in a Tedlar (SKC Inc., Eighty-Four, PA) gas sampling bag. Samples were with drawn using gas tight Hamilton syringes (Fortuna PE/PP, W Graf GmbH & Co., Werthein, Germany) and a standard curve was generated on a gas chromatograph (gc).

Exposure levels in the inhalation chambers were monitored by withdrawing samples on at least hourly intervals using a gas tight syringe. The sample was analyzed by gc and compared to the standard curve. The gas chromatograph used for this analysis was a Hewlett Packard 5890 (Hewlett Packard, Wilmington, DE) with a heated valve and split injection system. It was fitted with a GS-Q, 5 m X 0.53 mm id stainless steel capillary column and a flame ionization detector. Chamber exposure levels were calculated using a Thermo Separation Products PC 1000 software integrator (Thermosystems Products, Fremont, CA).

For in vitro studies, the concentration of HFC 245fa was determined in the head space above the culture medium before and after exposure. As described for the in vivo studies, samples were removed from the exposure system using a gas tight syringe, analyzed by gas chromatography, and the concentration determined by reference to the standard curve. The gc instrument, column, detector, and conditions varied depending on equipment availability.”

"Developmental Toxicity Studies

Initially a range-finding study was conducted using five groups of 12 time-mated, specific pathogen-free rats (Crl:CD BR VAF/Plus; Charles River UK, Margate, Kent, UK). They were exposed to levels of 0 (control), 500, 2000, 10,000, and 50,000 ppm. As there were no obvious treatment-related effects on the litters or litter parameters, the main study was initiated at the same exposure levels. This study consisted of five groups of 25 time-mated rats (Crl:CD BR VAF/Plus). The procedures followed and evaluation criteria have been described elsewhere (Rusch et al., 1995)."

"The main teratology study utilized exposure levels of 0 (control), 503 ± 37, 2070 ± 120, 10,350 ± 360, and 51,900 ± 2400 ppm v/v, respectively. Each group consisted of 25 timemated females. Exposures were conducted for 6 h per day on days 6-19 of gestation.”

Note: Dose levels were converted from ppm to mg/m3 by the extractor.

F1 Male and Female Specific Pathogen Free Rats