Event-related potentials in medical workers with long-term exposure to xylene

The effects of chronic exposure to xylene on cognitive ability were studied in a group of 35 medical workers occupationally exposed to low-level conce ntrations of xylene for at least five years by using event-related potentia ls (ERPs), and compared with a control group of 21 subjects. The exposure t o xylene was confirmed through determination of m-methylhippuric acid, a re liable biological indicator of xylene exposure, in pre- and post-shift urin e. A dose-effect relationship between log m-methylhippuric acid and ERP log latency (p = 0.032), and the ERP amplitude (p = 0.047) was statistically s ignificant. The group of medical workers showed significantly longer ERP lo g latency (p < 0.002) than did the control group with respect to factors of exposure to smoking, education and age as covariates. For the ERP amplitud e the difference was found not to be significant (p = 0.263), probably due to high between subject variability. The cognitive impairment may occur in workers chronically exposed to xylene.