The Tier 1 exposure tools ECETOC TRA, MEASE, STOFFENMANAGER, EMKG-EXPO-TOOL and RISKOFDERM used for REACH are designed to be simple and easy to use by a range of assessors and to provide conservative estimate of exposure. The eteam Project aimed to carry out a comprehensive evaluation of the Tier 1 exposure tools. This report provides a summary of the main results of the evaluation together with the authors' assessment of the main implications. Recommendations are made for tool developers, users and regulators. The project incorporated a range of qualitative and quantitative evaluation methods in the different work packages. These methods are detailed in the accompanying deliverable reports.
The tools differ in their underlying basis and in the number and definition of a limited range of input parameters. The tools were considered to be user-friendly and easy to access, download and use. However, extremely large variability was observed in outputs generated by a group of representative tool users (n=146) when assessing identical exposure situations. A small number of input parameters drove most of the variation; the task descriptor (PROC code or handling description), risk management measures and type of setting. This type of variability has been identified with all exposure assessment tools involving subjective assessment of parameters. An evaluation of tool uncertainty found that the type and level of uncertainty was heavily dependent on the individual situation being assessed, and should be considered in the context of the overall uncertainty of the exposure assessment process. The uncertainty arising from using Tier 1 tools is designed to be addressed by providing conservative estimates of exposure. Estimates of the tools were generally conservative, but did not always provide estimates that would be considered as a reasonable worst-case (as defined by the 90th percentile of exposure). Correlations between the measurement results and tool predictions were generally stronger for powders and non-volatile liquids than for the other exposure categories.
Comparison with measurement data suggested that the tools were generally conservative, but perhaps not always sufficiently so when compared with the reasonable worst case estimates as defined by the 90th percentiles of the exposure distribution. STOFFENMANAGER appeared to provide the most balanced performance with regard to the level of conservatism and predictive power for volatile liquids and powders. Furthermore, systems should be developed and applied to reduce the extreme levels of variability between users. Tool users must be more aware of the appropriate operation of the tools and their limitations. Improved quality assurance procedures including user certification and round-robin exercises, together with team-based assessments, the application of different models in tandem and corroboration of tool estimates with any available measurement data, should help improve the reliability of all of the tools.
J. Lamb, S. Hesse, B. G. Miller, L. MacCalman, K. Schroeder, J. Cherrie, M. van Tongeren:
Evaluation of Tier 1 Exposure Assessment Models under REACH (eteam) Project - Final Overall Project Summary Report.
1. edition. Dortmund: Bundesanstalt für Arbeitsschutz und Arbeitsmedizin 2015.
ISBN: 978-3-88261-160-1, pages 169, Project number: F 2303, PDF file