The EU Scientific Committee on Occupational Exposure Limits (SCOEL) set an occupational exposure limit (OEL) of 50 ppm for toluene. Finland’s CoRAP evaluation then recommended that this limit be reviewed. With no evaluation yet from ECHA’s Committee for Risk Assessment, the Lower Olefins and Aromatics (LOA) REACH Consortium carried out its own independent evaluation.
The review drew on previous regulatory assessments and an updated literature search, and evaluated the critical effects of toluene exposure: nervous system and neurobehavioural toxicity, colour vision effects, hearing loss, and reproductive and developmental toxicity. Human studies were assessed for relevance and quality, and animal studies using the Klimisch criteria. OELs were derived from the most conservative no-effect levels using standard ECHA guidance. Human occupational data from a large, diverse worker population generally gave more conservative limits than the animal data.
The evaluation recommends an 8-hour time-weighted average OEL of 20 ppm. Physiologically-based pharmacokinetic (PBPK) modelling of peak blood concentrations showed that a 15-minute short-term exposure limit (STEL) of 100 ppm would protect against adverse effects. Because toluene is readily absorbed through the skin, a skin notation is also recommended.
Authors
Martijn Rooseboom, Neslihan Aygun Kocabas, Richard James Radcliffe, Lawrence Segal
EUROTOX 2023, Poster P24-11 (Regulatory Toxicology), Abstract ID 182.