Biological exposure limits estimated from relations between occupational styrene exposure during a workweek and excretion of mandelic and phenylglyoxylic acids in urine.

Styrene exposure of 18 workers in fiberglass reinforced plastic industries was measured for 30-min periods throughout each workday for a week. The styrene uptake was estimated using pulmonary ventilation measurements. All urine voidings were collected separately and the styrene metabolites, mandelic acid (MA) and phenylglyoxylic acid (PGA) were determined. The relationship between both exposure and uptake versus excretion of these metabolites was studied. Styrene metabolite concentrations and excretion rates (with 95% tolerance limits) were calculated to correspond to a constant 8-h exposure at the Swedish exposure limit level (25 ppm) or an uptake of an exposure limit related styrene dose (6.3 mmol). The tightest tolerance limits were obtained for excretion rate of MA + PGA per 24 h. The calculated biological exposure limit was 3.4 (+/- 0.7) mmol MA + PGA/24h for a dose of 6.3 mmol styrene.