Styrene — Workplace Exposure Limit Change

Styrene was reclassified as a Group 2A probable carcinogen by IARC in 2019, based on limited evidence of lymphohaematopoietic malignancies in humans and sufficient evidence of tumours in experimental animals. Styrene is also ototoxic, meaning it damages hearing through a mechanism independent of noise exposure. Workers exposed to both styrene and noise experience synergistic hearing loss greater than either exposure would cause alone. Acute exposure causes central nervous system depression with symptoms including headache, fatigue, dizziness, and impaired concentration. Chronic exposure at levels below the current WES has been associated with colour vision impairment, decreased reaction time, and neurobehavioural effects. Respiratory irritation occurs at concentrations above 20 ppm, and dermatitis from direct skin contact with liquid styrene is common in laminating and moulding operations.

Personal air sampling using a calibrated pump at 0.05 to 0.2 L/min with coconut shell charcoal tubes (100/50 mg sections). Desorption with carbon disulphide and analysis by gas chromatography with flame ionisation detection following NIOSH Method 1501 or AS 2986. Biological monitoring of urinary mandelic acid and phenylglyoxylic acid at end of shift provides a complementary measure of absorbed dose.