"GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION

- Exposure apparatus: Glass and stainless steel chambers of approximately 750 L volume. Control modules were in a 1000-L chamber

- Method of holding animals in test chamber: Individually housed in a stainless steel, wire basket, exposure module

- Source and rate of air: Filtered, conditioned air

- Method of conditioning air: Not reported

- System of generating particulates/aerosols: Test atmospheres were generated by metering the liquid test material into a J-tube filled with glass beads. Heated air, approximately 60°C, was blown through the glass beads to evaporate the test material. The resulting vapour was diluted by filtered, conditioned air to the target concentration for each of the test chambers. Conditioned, heated air alone was metered in an identical manner into the control chamber. The chambers were operated in a one-pass, ow-through mode to enable adequate distribution of the test material throughout the chamber, to provide sufficient oxygen for the test animals, and to prevent contamination from volatiles derived from excreta. The position of the exposure modules within each chamber was rotated each day to minimize any possible effects of uneven vapour distribution. At the end of each / exposure, rats remained in their chambers long enough to allow clearance of the test material from the chamber atmosphere.

- Temperature, humidity, pressure in air chamber: 17-27°C, 23-100%, pressure not reported

- Air flow rate: Not reported

- Air change rate: at least 12 air changes per hour

- Method of particle size determination: Not reported

- Treatment of exhaust air: Chamber exhaust was diluted with room air and exhausted through a roof stack.

TEST ATMOSPHERE

- Brief description of analytical method used: Chamber atmospheres were analyzed at least hourly during each 6-hour exposure period by gas chromatography. The isomer ratio in an air sample collected from one of the test chambers was determined once daily.

- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations: yes

Details on analytical verification of doses or concentrations: Method of Analysis: GC Mean chamber concentrations were always within 10% of the targeted concentration, with the exception of two minor excursions. The mean concentrations achieved for the 2000 ppm concentration were slightly low (86 or 81% of target) on two days. Analyses demonstrated that the test substance was stable over the course of the study. Overall mean concentration was 501.8, 1940.3, and 3475.5 ppm for the 500, 1000, and 4000 ppm concentrations, respectively

No. of animals per sex per dose: 25 females

Control animals: yes

Details on study design: - Dose selection rationale: A 2-week nose-only inhalation study at 0, 500, 1000, and 4000 ppm revealed minimal compound related effects. A rangefinding study was conducted, with whole-body exposures, for 3 or 4 exposures at 5000 or 7000 ppm. Clinical signs of toxicity, consisting of seizure-like behaviour, occurred at concentrations as low as 3700 ppm. The / doses for this study were selected so the highest concentration was below the threshold at which seizure-like activity occurred."

P0 Female Crl:CD(SD)BR Rats