Review of reference values for the assessment of inhalation risks for workers at industrial contaminated sites

This study examines the procedures used to assess the inhalation risks of workers exposed to chemicals emitted from contaminated environmental matrices ("environmental exposure") or to substances present in the productive cycle ("occupational exposure"). For the environmental exposure, the limit values for workers set by U.S. EPA (RBSLair) were considered. For the occupational exposure, the values set by EU directives (OELVs) and in the REACH regulation (DN(M)ELs) were examined. Despite a similar derivation methodology, the assessment and uncertainty factors employed to derive the RBSLair are more conservative than the corresponding factors adopted to calculate OELVs and DN(M)ELs. These differences can be ascribed to the toxicological parameters adopted for calculating RBSLair for workers that, although with different exposure factors, are the same used to calculate the limit values for sensitive receptors (e.g., children and the elderly). The comparison carried out on 110 substances typically of concern in contaminated sites showed that RBSLair for workers are noticeably more conservative than the corresponding OELV and DN(M)EL. RSBLair are more than two orders of magnitude lower than OELV and DN(M)EL for 50% of the examined substances and over three orders of magnitude in 25% of cases. In the future, a harmonization is desirable as, currently, the risk assessment for the same receptor and the same substance can lead to completely different outcomes depending on whether environmental or occupational exposure is considered.