Evaluation of low exposure to styrene. I. Absorption of styrene vapours by inhalation under experimental conditions.

Volunteers (six men and one woman) were exposed by inhalation to styrene within the concentration range of 20 to 200 mg/m3. The average retention of styrene vapours in the respiratory tract was 71%. The yield of styrene metabolism measured within 24 h was 39 and 17% for mandelic acid and phenylglyoxylic acid, respectively. The determination of mandelic acid in urine collected immediately after the exposure was applied as exposure test. The excretion rate of this metabolite assured the best correlation with the absorbed dose. The relative standard deviations of the test related to actual dose level vary, depending on the analysed concentration range, from 0.21 to 0.33. Quantitative interpretation of the test is possible for styrene concentrations in the air exceeding 20 mg/m3. The concentration amounting to 100 mg/m3 (TLV) corresponds with the mandelic acid excretion rate of 15 mg per hour.