The effect of an unusual workshift on chemical toxicity. II. Studies on the exposure of rats to aniline.
Fundam Appl Toxicol 1986 Jul; 7(1):144-152
The effects of altering the exposure schedule of rats from 8 hr/day for 5 days to 12/hr per day for 4 days on the resulting toxicity from the inhalation of aniline (62533) at 10, 30, 50 and 150ppm were investigated. With 150ppm exposures, the aniline induced effect on methemoglobin level was cumulative in both groups, but more pronounced in the 12 hour/day exposure group than in the 8 hour/day exposure group. At 50ppm, the methemoglobin levels in the 8 hour/day exposure group returned to the nonexposed control value after overnight recovery, but in the 12 hour/day exposure group, levels did not return to the control value, and increased with the days of exposure. Recovery in this group was not complete even after a three day weekend. The authors conclude from this study that careful examination of the toxicology and pharmacokinetics of each substance should be made prior to accepting any formula approach for adjusting the exposure limits for unusual workshifts. This is especially important because the pharmacokinetic parameters of most industrial chemicals are based on observations following single 4 to 6 hr exposures. Increasing numbers of workers in industry are working a 12 hour workshift in which the exposure time is longer and the recovery period is shorter. A more conservative model such as those based on the exposure time and recovery period is recommended to modify the exposure limit for workers on prolonged workshifts.
NIOSH-Publication; NIOSH-Grant; Laboratory-animals; Dye-industry; Pharmaceutical-industry; Solvents; Resins; Work-intervals
Fundamental and Applied Toxicology
Pharmacology and Toxicology Purdue University Dept Of Pharmacology & Toxic West Lafayette, Ind 47907