Quality assurance of biological monitoring in view of risk management

Summary

Since recommended occupational exposure limits both for workplace air concentration and biological monitoring results generally have very narrow margin of protection, the probability of the false decision due to measurement error should be perceived and carefully controlled. Japan Federation of Occupational Health Organization has conducted large scale quality control programs since 1987 and reported the results in detail. The meta-analysis of the report of 1992 made it clear that the qualities of the analysis of the leading laboratories as expressed by the coefficient of variation of measurement error are mostly about 5% or less. It was suggested that the warning level should be set at (biological exposure limits minus 2 SD of the measurement error). However, it will not be needed when the SD is less than 2.5% as was found for the analyses of blood lead, urinary hippuric acid, methyl hippuric acid, and mandelic acid by a few best performing laboratories.