Proposal for a neurotoxic classification for chemicals at work.

Many neurotoxic chemicals are used in the workplace but there is currently no database dedicated to neurotoxicity. We aimed to develop a classification method for neurotoxicity based on a weight-of-evidence approach, similar to the IARC classification for carcinogenicity. Human and animal lines of evidence were collected from recent toxicological profiles and a literature search and were combined into six groups from neurotoxic to potentially not neurotoxic. The method was tested on 26 chemicals, mixtures or group of products used in the workplace in France: 31% were considered neurotoxic, 31% probably and 11% possibly neurotoxic, and 27% not classifiable because of insufficient data. This operational method suggests that many chemicals used in the workplace are neurotoxic and that questionnaires used to collect data on occupational chemical exposure should propose items with more targeted compounds that have common chemical or toxic properties to improve risk assessment.