Cross-validation and refinement of the Stoffenmanager as a first tier exposure assessment tool for REACH

Abstract

Objectives For regulatory risk assessment under REACH a tiered approach is proposed in which the first tier models should provide a conservative exposure estimate that can discriminate between scenarios which are of concern and those which are not. The Stoffenmanager is mentioned as a first tier approach in the REACH guidance. In an attempt to investigate the validity of the Stoffenmanager algorithms, a cross-validation study was performed.Methods Exposure estimates using the Stoffenmanager algorithms were compared with exposure measurement results (n¼254). Correlations between observed and predicted exposures, bias and precision were calculated. Stratified analyses were performed for the scenarios "handling of powders and granules" (n¼82), "handling solids resulting in comminuting" (n¼60), "handling of low-volatile liquids" (n¼40) and "handling of volatile liquids" (n¼72).Results The relative bias of the four algorithms ranged between À9% and À77% with a precision of approximately 1.7. The 90th percentile estimate of one out of four algorithms was not conservative enough. Based on these statistics and analyses of residual plots the underlying algorithm was adapted. Subsequently, the calibration and the cross-validation dataset were merged into one dataset (n¼952) used for calibrating the adapted Stoffenmanager algorithms. This new calibration resulted in new exposure algorithms for the four scenarios. Conclusions The Stoffenmanager is capable of discriminating among exposure levels mainly between scenarios in different companies. The 90th percentile estimates of the Stoffenmanager are verified to be sufficiently conservative. Therefore, the Stoffenmanager could be a useful tier 1 exposure assessment tool for REACH.

Application of predictive models for estimation of health care workers exposure to sevoflurane

“…A worst case estimation based on the 90th percentile of the exposure distribution or other percentile of the exposure distribution can be assessed. [21,24] Based on the observations, the maximum concentration of sevoflurane in a mixture of breathing gases was assumed to be 3%, as the worst possible scenario. Air samples were collected for at least 6 h, but the employees were not exposed to anaesthetics throughout the whole work shift.…”

Stoffenmanager Exposure Model: Company-Specific Exposure Assessments Using a Bayesian Methodology

“…(3) The regression models have recently been further tested and refined in a cross-validation study. (4) Stoffenmanager is proposed as one of the available generic Tier 1 tools for exposure assessment under REACH, the European chemicals legislation. Manufacturers and importers of dangerous substances are required to develop exposure scenarios that describe how risks of the substances can be controlled for workers, the general population, and the environment.…”

Comparison and Evaluation of Multiple Users’ Usage of the Exposure and Risk Tool: Stoffenmanager 5.1

“…Validation studies of the quantitative exposure part of Stoffenmanager (Koppisch et al 2012;Schinkel et al 2010) showed that it was sufficiently conservative; however, no study has evaluated the reliability of either the quantitative exposure part or the control banding part to explore whether and how the results vary when multiple users study the same scenarios.…”

“…= with protection. Working in a cabin 3 0.03-1 (a) a: (Marquart et al 2008) b: (Schinkel et al 2010) c : 8 is for liquids and 14 is for dusts 2 This scenario is outside the scope of Stoffenmanager and will therefore only be presented in tables.…”

“…The tool originally had a qualitative control banding module that rated risks as low, medium, or high. Later, a quantitative part was developed to predict exposures as mg/m 3 , which was validated and recalibrated into today's version 5.1 (Schinkel et al 2010). …”