Neurobehavioral performance in workers exposed to toluene

Abstract

Toluene is widely used in adhesive, printing, painting and petroleum industries in many countries. This study was conducted to examine the effect of chronic exposure to toluene below 100 ppm on neurobehavioral performance using a computerized neurobehavioral test battery that emphasizes simple instructions and practice prior to testing. The Behavioral Assessment and Research System (BARS) with Korean language instructions was administered to 54 workers from three different industries: oil refinery, gravure printing, and rubber boat manufacturing. The battery consisted of the following tests: Digit Span (DS), Simple Reaction Time (SRT), Selective Attention (SAT), Finger Tapping (FT), and Symbol Digit (SD). Urine was collected at the end-of-shift to analyze urinary hippuric acid to assess exposure level to toluene. Based on the previous air toluene level, workers were divided into three groups: Low (21 workers, less than 10 ppm), Moderate (13 workers, 20–30 ppm) and High (20 workers, 70–80 ppm) exposure status. Analysis of Covariance (ANCOVA) adjusting for age, education and work duration as covariates, was performed to examine the relationship between the neurobehavioral performance and the exposure groups. Poorer performance of the High exposure group was found on FT-preferred ( F = 7.034, p = 0.002) and SAT latency ( F = 11.710, p = 0.000). Age showed a significant correlation with SD ( r = 0.417, p = 0.002) and SAT number correct ( r = −0.460, p = 0.000). Years of education and work duration were not significantly correlated with any items. This study supports that toluene exposure below 100 ppm is associated with neurobehavioral changes and that high-level toluene exposure could cause not only attention and concentration, but also motor performance deficits.