LOF A, LUNDGREN E, NYDAHL E-M, BYFALTNORDQVIST M. Biological monitoring of styrene metabolites in blood. Scand J Work Environ Health (1986) 70-74. Ten men occupationally exposed to styrene in two glass-fiber reinforced plastics factories were studied during three consecutive workdays. The mean external exposure level was 99 mg/m", The total pulmonary uptake of styrene was estimated from measurements of the styreneconcentrationin inspiredair, the pulmonary ventilation,and the relative uptake. A gas chromatographic method based on electron capture detection was used to quantify styrene glycol,as wellas styrene-7,8-oxide, in blood. The concentration of styrene glycolappeared to be linearly related to the preceding uptake of styrene. When the uptake during 5 h immediately before the blood sampling was considered, the correlation coefficient (r) obtained the value of 0.90. The concentration of styrene-7,8-oxide wasat the detection limitof 0.02Itmolllin most samples. A weakercorrelationbetween the concentration of styrene in blood and the uptake during the hour immediately preceding the blood sampling was obtained (r=0.71).