Styrene toxicity values according to the scenario of exposure
Résumé
Styrene is an aromatic hydrocarbon compound mostly used as a monomer in the manufacture of plastics. The presence of styrene in the environment is mainly anthropogenic. Styrene is a substance of interest in risk assessment and risk management for humans for which one need reference values. Depending on the exposure scenario, the reference values used are not the same. In the case of chronic exposure to styrene, the National Institute for Industrial Environment and Risks (INERIS) has made a choice among the existing toxicological reference values determined by international agencies. In the context of land use planning, acute toxicity threshold values were established by INERIS. For each of these scenarios, a methodology was developed by INERIS. In both cases, the first step is an extensive literature review of available data. Then, for chronic exposures, the toxicological reference values are selected according to their scientific quality and their relevance. For acute inhalation exposures in accidental situations, determination of threshold values is based on the Klimisch scoring from selected studies and on statistical modeling from experimental data. For chronic exposure, INERIS recommend the use of 0.2 mg kg-1 j-1 for oral chronic exposure to styrene (US EPA) and 0.2 ppm for inhalation chronic exposure (ATSDR). For acute inhalation in accidental situations, the inhaled doses corresponding to thresholds for acute lethal effects are 75,000-120,000 ppm min and 12,000-48,000 ppm min for the irreversible effects.