Temporal, personal and spatial variability in dermal exposure.

A database of dermal exposure measurements (DERMDAT) comprising data from 20 surveys was created. The majority of dermal exposure measurements were from agricultural settings in which workers' exposure to pesticides was investigated. Other data came from studies of workers exposed to polycyclic aromatic hydrocarbons (e.g. coke-oven workers and paving workers) and from studies of subjects exposed to complex mixtures (rubber industry). The database contains approximately 6400 observations. Grouping the workers by job title, factory and body location and excluding groups with more than 25% data below the limit of detection, or with less than two workers with at least two repeats, resulted in 283 groups with 1065 workers and 2716 measurements. Analyses of variability showed median values of the total, within- and between-worker geometric standard deviations of respectively 2.55, 1.98 and 1.47, strikingly similar to what has been published previously for respiratory exposure. Within-worker variability ((w)S(2)y) was in general higher than between-worker variability ((b)S(2)y) in dermal exposure levels. Agricultural groups of re-entry workers showed very little to no between-worker variability, while industrial groups did show some variability in individual mean exposures (range (b)S(2)y=0.15-0.29). When the between-body-location component (bl)S(2)y) was also addressed, it turned out to be the most prominent component (median (b)S(2)y=0.004; median (w)S(2)y=0.12; median (bl)S(2)y=0.34). In agriculture the between-body-location component was smaller than in industry. Day-to-day variability in dermal exposure levels appeared to be significant for specific locations, but not for the average of several body-location. Underlying exposure scenarios (transfer and deposition) also played an important role.