Two weeks inhalation exposure to 4-tert-butyltoluene causes persistent changes in visually evoked potentials in rats.

The effects of repeated exposure to 20 p.p.m. 4-tert-butyltoluene (CAS No. [98-51-1]) 6 hr/day for 14 days on the function of the intact nervous system were examined by measurements of flash evoked potentials in Wistar rats. The exposure to 4-tert-butyltoluene induced changes in the amplitudes of the flash evoked potentials. The changes were significantly different from controls on day 2, 19 and 26 after cessation of the exposure, but not on day 5 and 12. No significant difference in body weight gain between groups was found during the experiment. These results indicate that repeated exposure to 20 p.p.m. 4-tert-butyltoluene causes persistent changes in the function of the central nervous system measured as changes in the flash evoked potential. A reevaluation of the present TLV value of 10 p.p.m. for 4-tert-butyltoluene is suggested.