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.

本研究针对两类暴露场景下作业人员的吸入风险评估流程展开探讨：一类为暴露于受污染环境介质所释放化学物的环境暴露（environmental exposure），另一类为暴露于生产流程中存在物质的职业暴露（occupational exposure）。针对环境暴露场景，本研究采用了美国环境保护署（U.S. EPA）设定的工人吸入暴露参考限值（RBSLair）；针对职业暴露场景，则分别考察了欧盟指令规定的职业接触限值（OELVs）以及欧盟REACH法规（REACH regulation）中明确的推导无明显有害效应浓度（DN(M)ELs）。尽管两类限值的推导方法具有相似性，但用于推导RBSLair的评估方法与不确定因子（uncertainty factors），相较于计算OELVs和DN(M)ELs所采用的对应参数更为保守。上述差异可归因于：用于计算作业人员RBSLair的毒理学参数，虽暴露因子存在差异，但与用于计算敏感受体（sensitive receptors，如儿童、老年人）限值的参数完全一致。对污染场地（contaminated sites）中常见的110种关注物质开展的对比分析显示，作业人员的RBSLair显著严于对应OELVs与DN(M)ELs。在本次考察的物质中，有50%的物质对应的RBSLair较OELVs和DN(M)ELs低两个以上数量级（orders of magnitude），25%的物质甚至低三个以上数量级。未来亟需开展统一协调工作：当前针对同一受体与同一物质的风险评估，若分别基于环境暴露与职业暴露场景开展，可能得出完全迥异的结果。