104 Evaluating multi-establishment SEG variability: results from the brick manufacturing sector

The seminal works of Rappaport (1991) and Kromhout et al. (1993) highlighted the importance of Similar Exposure Group (SEG) variability in occupational exposure assessment. In 2019, we started a research program to test a methodology for defining multi-establishment SEGs, i.e. groups including workers from different establishments, as opposed to the usual “mono-establishment” approach. Our research included both data from two French occupational exposure databases, managed by INRS, and the field observations and measurements we performed in various industrial sectors. To be included in our analysis, establishments had to share similar characteristics and occupational hygiene standards. Here we present results from the brick manufacturing sector, showing the effect of workplace on SEGs variability. For this sector, we collected 252 personal measurements of crystalline silica, covering 8-hour shifts. We estimated by ANOVA the within- and between- components of SEGs variability and we calculated for each SEG the rho heterogeneity coefficient and the R ratio, which were initially proposed for assessing worker variability. Rho values were comprised between 0.001 and 0.49, with a median of 0.12. The R ratio was comprised between 1.15 and 4.46, with a median of 2.70. Results showed moderate variability for five out of eight inter-establishment SEGs, high variability for two SEGs and low variability for one SEG, in good agreement with the results obtained by expertise. Future analyses will aim at better define homogeneity criteria for multi-establishment SEGs, taking into account their higher complexity compared to the classic mono-establishment SEGs.