Use of uncertainty factors by the European Commission Scientific Committee on Occupational Exposure Limits: a follow-up

Abstract

Decision on the safety margin, for instance by using uncertainty factors (UFs), is a key aspect in setting Occupational Exposure Limits (OELs). We analyzed the UFs in 128 OEL recommendations from the European Commission’s Scientific Committee on Occupational Exposure Limits (SCOEL). We investigated factors expected to potentially influence the UFs, as well as a selection of factors that might influence how expert groups perceive quality or reliability of key studies. We extracted UFs explicitly stated in the recommendations (EUFs) and, when EUFs were missing, calculated an implicit safety margin (ISM) by dividing the point of departure (PoD) by the OEL. EUFs and ISMs were lower for recommendations based on human data than those based on animal data. EUFs and ISMs were also lower for No-Observed Adverse Effect Concentrations (NOAECs) than Lowest Observed Adverse Effect Concentrations (LOAECs). We saw no differences based on local vs systemic critical effects. Acute data resulted in lower EUFs and ISMs than subchronic. We saw no influence from status of key study (publication status, performer or funder), but high tonnage substances (1,000,000+ tonnes) have lower EUFs and ISMs than substances currently not registered under REACH. Although SCOEL methodology stated that UF should be documented, only 65 out of 128 OEL recommendations included an EUF. Indeed, the ratio of EUFs to ISMs even decreased from 1991–2003 to 2004–2017. Additionally, EUFs were, on average, 1.8 times higher than ISMs. We conclude that a more articulate framework for using UFs could enhance consistency and transparency of the SCOEL recommendations.

Keywords:

• Assessment factor
• safety factor
• risk assessment
• occupational health and safety
• chemicals regulation

Acknowledgements

The authors thank the five reviewers selected by the Editor and anonymous to the authors for insightful and constructive comments which were very helpful in improving the manuscript.

Declaration of interest

Gunnar Johanson is a member of SCOEL. The authors? affiliations are as shown on the cover page. Neither of the authors have appeared in any legal or administrative proceedings related to the contents of the paper with the exception that Gunnar Johanson (as a member of SCOEL) participated in the task Joint Task Force ECHA Committee for Risk Assessment (RAC) and SCOEL on Scientific aspects and methodologies related to the exposure of chemicals at the workplace. This work was funded by the Swedish Research Council for Health, Working Life and Welfare (FORTE) [grant number 2016-00229], which is a government agency under the Swedish Ministry of Health and Social Affairs. The funding agency had no role in the research performed, writing of the manuscript or the decision to submit.

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