Comparison of measured and modeled data for carcinogen workplace exposure assessment: a case study on chromium...

Occupational exposure to chromium trioxide (CAS number: 1333-82-0) remains a major concern in the electroplating sector. Risk assessment is regulated under both the REACH Regulation, which focuses on substance-related risks across the supply chain, and Occupational Safety and Health (OSH), which emphasizes workplace-specific exposure. The two regulatory frameworks adopt different approaches, particularly regarding the role of exposure models and monitoring for workplace risk assessment. This study investigated the outcomes of exposure assessment under REACH and OSH, comparing modeled exposure estimates with measured workplace data for occupational exposure to hexavalent chromium, in order to analyze differences in the exposure assessment process and the risk characterization under both approaches.

The study focuses on four Italian companies involved in metal products manufacturing, which applied to ECHA for authorization to use chromium trioxide. Worker contributing scenarios were defined from Chemical Safety Reports. Exposure estimates were derived using the Advanced REACH Tool, while additionally measured data came from workplace monitoring campaigns, evaluated according to EN 689:2019. Comparisons between exposure estimates and measured data were made following the criteria of level of consistency and level of conservatism. Considerations on risk as risk characterization ratio (RCR) under OSH and excess risk under REACH were also made due to the different regulatory approach.

Model estimates from ART frequently have allow level of consistency with measured workplace concentrations, in some cases by up to two orders of magnitude. RCR values calculated from each exposure measured and estimated data were always <1, although EN 689 testing revealed cases of noncompliance. Excess risk under REACH remained below the tolerable level defined but was closer to it than to the acceptable level.

The analysis highlighted fundamental differences between REACH and OSH: REACH relies mostly on exposure models for registration. For Application for Authorizations, monitoring is more frequently applied. On the other hand, OSH prioritizes monitoring of carcinogenic agents by workplace measurements in any case. Models are useful tools, but their reliability depends amongst others on assessor expertise and contextualization with workplace data. Integrating REACH authorization conditions with OSH monitoring obligations can create a more consistent and effective strategy to protect workers from Cr(VI) exposure. As the concept of risk is framed differently in REACH and OSH, this study highlights how the exposure tools may be used at different levels, leading to mutual benefits for both approaches.