THE EFFECT OF AN UNUSUAL WORKSHIFT ON THE TOXICOLOGY OF INDUSTRIAL CHEMICALS. STUDIES ON THE EXPOSURE OF RATS AND MICE TO DICHLOROMETHANE AND ANILINE (INHALATION, NOVEL WORKSHIFT, TLV)

YOUNG CHUL KIM, Purdue University

Abstract

Over the past few decades a number of industries have adopted unusual workshifts often involving a 3 or 4 day workweek of 12 hr/day. Experiments were conducted to compare the effects of the 12 hr exposure schedule to those of 8 hr schedule on the toxic responses induced by dichloromethane (DCM) and aniline. Rats and mice were exposed to 200, 500 or 1000 ppm DCM for 8 hr/day for 5 days or 12 hr/day for 4 days. The effect of the unusual exposure schedule on carboxyhemoglobin (COHb) levels was not significant. The pathway for the formation of COHb was saturated even at the lowest concentration of DCM. The peak blood level of DCM was dependent upon the DCM exposure concentration, but the half-life was independent of the duration of exposure and the concentration of DCM. The half-life of COHb in blood was prolonged by increasing the DCM concentration, but was not affected by the exposure period. Pyrazole treatment decreased COHb level and increased blood DCM levels whereas SKF 525-A and cobaltous chloride did not affect the rate of DCM elimination from blood. Rats were exposed to 10, 30, 50, 130 or 150 ppm aniline on the two different exposure schedules. Residual MetHb levels were significantly higher in the 12 hr exposure groups at 50, 130 and 150 ppm. The post-exposure MetHb measured following each exposure increased with repeated exposure in both groups. The half-lives of aniline in blood and fat were approximately 4 hrs following exposure to 100 ppm aniline for 8 or 12 hrs. Exposures for 3 days did not result in differences in the amount of aniline in blood or fat between the 8 hr and 12 hr exposure groups following the last exposure. Blood aniline was significantly higher in the 12 hr group on the next morning. The hematocrit showed a decrease which was dependent upon the aniline concentration but not upon the exposure schedule. The results suggest that the exposure limits should be adjusted, depending upon the nature of each chemical, for an unusual workshift. The acceptance of any formula approach proposed must be determined once the toxicology and behavior of the toxicant is thoroughly understood.

Degree

Ph.D.

Subject Area

Pharmacology

COinS