Comparison of self-assessment and expert assessment of occupational exposure to chemicals

Objectives Occupational assessments of chemical exposure are often inadequa te because of difficulties in obtaining sufficient numbers of measurements by trained professionals (experts). The objective of this study was to dete rmine whether workers can provide unbiased data via self-assessments of exp osure facilitated by the use of simple passive monitors for personal sampli ng. Methods Untrained workers obtained personal measurements of their exposures to gaseous contaminants (terpenes in sawmills and styrene in reinforced pl astics factories) with passive monitors and written instructions. To study the validity of the self-assessments, an occupational hygienist performed e xposure measurements on the same occupational groups after the workers had obtained two or more measurements independently. The potential bias of the self-assessments was evaluated by comparing the self-assessments with the e xpert assessments in mixed-effects statistical models. Results A total of 153 terpene (97 self and 56 expert) and 216 styrene (159 self and 57 expert) measurements were obtained from four sawmills and six reinforced plastics factories, respectively. No significant differences in the geometric mean exposures were observed between the self-assessments and the expert assessments in 3 of 4 sawmills and 5 of 6 reinforced plastics f actories (P > 0.10). The potential bias of the self-assessments of exposure ranged from less than 0.1% to 102% and was less than 17% in 9 of the 10 gr oups investigated. Conclusions The results indicate that untrained, unsupervised workers are a ble to collect consistently unbiased exposure data by employing currently a vailable passive monitors.