[Problems in the biological monitoring of benzene exposure].

The biological monitoring of workers exposed to benzene containing mixtures by phenol analysis in urine is complicated by the facts that varying amounts of phenolic compounds are also produced by other precursors than benzene and that coexposure with other chemicals can cause interactions in metabolism and elimination rates. In order to overcome these difficulties it is proposed a) to abandon the colorimetric methods and to use only gas chromatography as a standard and reference method, b) as an overall monitoring concept always to determine phenol pre-exposure values as well as the cresol and creatinine concentrations in urine, and to combine biological monitoring whenever possible with personal air sampling.