Assessment of dermal exposure to bitumen condensate among road paving and mastic crews with an observational method

To assess dermal exposure to bitumen condensate among road pavers and indoor mastic workers in multiple crews using a semi-quantitative observational method [DeRmal Exposure Assessment Method (DREAM)].

Two skilled observers assessed dermal exposure to bitumen condensate among 85 asphalt workers from 12 crews from nine companies active within four European countries using the DREAM methodology, which produces an estimate of exposure expressed in dimensionless DREAM units. Both observers independently evaluated each crew member's job (N = 14 jobs) for road paving and mastic applications. Potential and actual dermal exposures were estimated for hands and for the rest of the body separately, taking into account the effect of protective clothing. To evaluate the reproducibility of the observational method intra-class correlation coefficients (ICCs) were estimated. The exposures in DREAM units were modelled using linear mixed models to estimate average relative scores for each job. Correlations between dermal exposure parameters were evaluated by estimating Pearson correlation coefficients.

A total of 170 observations were completed by two observers independently (n = 118 and n = 52 for 59 road pavers and 26 mastic workers, respectively) in 11 days. The mean ICCs (for potential and actual exposure in DREAM units) varied between 0.74 and 0.80 with values for actual units being slightly higher. Geometric mean potential dermal exposure units of mastic workers were higher than for road pavers (factor 3 for hands and factor 4 for rest of the body). Differences for actual dermal exposure units were smaller for hands (factor 2) and larger for actual exposure units of rest of the body (factor 5). Differences in dermal exposure at the hands between jobs within a paving crew were much larger than between jobs within a mastic crew. Within paving crews, a consistent pattern for all exposure units emerged with 'screed man' and 'raker' as the two highest exposed jobs. Within mastic crews, 'driver dumper truck' and 'spreader of mastic' were scored as the two jobs with the highest exposure units. Potential and actual exposure units were highly correlated. Hands were more profoundly exposed than the rest of the body, with transfer from contaminated surface to the hands as the most important route.

DREAM observations were reproducible and showed a consistent dermal exposure pattern among the observed crews. The study provided a clear picture of dermal exposure among road pavers and indoor mastic workers, with the mastic workers being considerably more highly exposed. The most important route of exposure appeared to be transferred from contaminated surfaces to the hands.