Quantitative self-assessment of exposure to solvents among shoe repair men

Self-assessment of exposure (SAE) refers to any exposure assessment methodology wherein the worker takes an active role in establishing his or her exposure status. The objective of this study was to investigate the reliability and feasibility of SAE approaches among shoe repair workers collecting exposure data over a 3 month period. This study was conducted in 26 Dutch shoe repair shops, which were divided into two groups of SAE with different levels of expert supervision. Participants in group 1 received only written instructions on sampling methods, whereas workers in group 2 were also instructed face-to-face by an occupational hygienist. Participants were asked to do 20 (group 1) or 14 (group 2) measurements by themselves. In group 2, an additional 6 measurements in each company were conducted under supervision of an expert. Organic solvents were measured by passive samplers (3M badges) and a sum score for volatile organic compounds (VOC score) was used in data analysis. Mixed effect models and principal component analysis were used to compare concentration levels and exposure variability between group 1 and group 2. Finally, 473 out of the 520 distributed samplers (91%) were available for analysis. Measurements in group 1 were not evenly spread over the 3 month period, whereas dispersal of measurements was much better if experts were more closely involved (group 2). No significant differences in average VOC scores were found between group 1 and group 2. The exposure variability in group 1 appeared to be significantly larger than that in group 2. However, analysis within group 2 showed that no differences exist in geometric means and exposure variability between 'expert' and 'self-assessment' measurements. Thus, the study results are ambiguous with respect to the reliability of SAE, and more research is needed to corroborate and refine the present results. This new methodology can, if proven reliable, be seen as a cost-effective way of collecting exposure data.