Exploring the statistical uncertainty in acceptable exposure limit values for hexavalent chromium exposure.

Exposure limit values give the exposure level at which an accepted (or acceptable) number of additional work related diseases are expected. The values are derived from dose-response curves and carry a large amount of uncertainty. In this paper we aim to quantify some of this uncertainty with statistical means. We explore the limit value issued by the European Chemical Agency (ECHA) for occupational exposure to hexavalent chromium, CR(VI). We investigate how the dose-response model and statistical estimation variability influences the data-based fixation of exposure limit values. We also look at the effect of measurement variation on the exposure level itself, where simulation techniques allow to quantify the uncertainty in statistical terms. We demonstrate that statistical uncertainty needs to be taken into account when fixing exposure limit values based on data.