Application of biological monitoring to the quantitative exposure assessment for neuropsychological effect by chronic exposure to organic solvents

Objective: Quantitative exposure assessment became more common as a result of attempts to reduce nondifferential exposure misclassification and to observe a steeper exposure-response relationship. Several exposure variables were compared in a demonstration of the exposure-response relationship between neuropsychological abnormality and long-term exposure to organic solvents in workers at one shipyard. Method: Environmental monitoring and biological monitoring were performed to evaluate the exposure of the workers to organic solvents. Cumulative exposure (CE) and lifetime-weighted average exposure variables were developed with both environmental and biological monitoring data. A neuropsychological questionnaire and a function test for confirmation of a disorder or dysfunction in attention, executive function, visuospatial, and constructional abilities, learning and memory, and psychomotor function were performed. Results: The abnormal rate in neuropsychological diagnosis was 9.3% in the exposed group, which was much higher than the 2.1% rate obtained in the nonexposed group (P < 0.01). The neuropsychological abnormal rate showed a significant dose-response association with CE created with biological monitoring data. The results also suggest that biological monitoring can provide impressive and effective information for quantitative exposure assessment, even in epidemiology studies. Received: 2 April 1998 / Accepted: 23 September 1998