Accuracy of a semiquantitative method for Dermal Exposure Assessment (DREAM)

Abstract

Background:The authors recently developed a Dermal Exposure Assessment Method (DREAM), an observational semiquantitative method to assess dermal exposures by systematically evaluating exposure determinants using pre-assigned default values. Aim: To explore the accuracy of the DREAM method by comparing its estimates with quantitative dermal exposure measurements in several occupational settings. Methods: Occupational hygienists observed workers performing a certain task, whose exposure to chemical agents on skin or clothing was measured quantitatively simultaneously, and filled in the DREAM questionnaire. DREAM estimates were compared with measurement data by estimating Spearman correlation coefficients for each task and for individual observations. In addition, mixed linear regression models were used to study the effect of DREAM estimates on the variability in measured exposures between tasks, between workers, and from day to day. Results: For skin exposures, spearman correlation coefficients for individual observations ranged from 0.19 to 0.82. DREAM estimates for exposure levels on hands and forearms showed a fixed effect between and within surveys, explaining mainly between-task variance. In general, exposure levels on clothing layer were only predicted in a meaningful way by detailed DREAM estimates, which comprised detailed information on the concentration of the agent in the formulation to which exposure occurred. Conclusions: The authors expect that the DREAM method can be successfully applied for semiquantitative dermal exposure assessment in epidemiological and occupational hygiene surveys of groups of workers with considerable contrast in dermal exposure levels (variability between groups .1.0). For surveys with less contrasting exposure levels, quantitative dermal exposure measurements are preferable.

Exposure profiles of pesticides among greenhouse workers: implications for epidemiological studies

“…It is likely that these significant differences in DREAM scores reflect true differences in mean dermal exposure among these tasks, since DREAM correlated reasonably well with dermal exposure measurements in a validation study. Spearman correlation coefficients for individual observations ranged from 0.19 to 0.82 (van Wendel de Joode et al, 2005b). This performance is comparable to that of a frequently used occupational model for inhalation exposure .…”

“…The geometric mean of total body DREAM scores (summation of hands and body scores; weighted according to surface area) of these tasks are towards the upper end of the DREAM score distribution produced in a comprehensive benchmark study (van Wendel de Joode et al, 2005b). This finding may help to prioritize adequate control measures and suggests that interventions should focus on these tasks.…”

“…This finding may help to prioritize adequate control measures and suggests that interventions should focus on these tasks. DREAM scores for other tasks, for example, bulb shower or horizontal ground boom, were comparable with values at the lower end of the distribution in the study of van Wendel de Joode et al (2005b). The benchmark study included 31 tasks representing a broad range of processes with low and high exposure potential.…”

“…In six exposure surveys, DREAM estimates were compared with dermal measurement data by estimating Spearman correlation coefficients. These ranged from 0.19 to 0.82 (van Wendel de Joode et al, 2005b).…”

Evaluation of models for dermal exposure assessment in farming systems in developing countries

“…For instance, DERM has not been validated and it has been criticized about the reliability and reproducibility of the outcomes as there were mistakes in the methodology when the model was developed and tested in the same study area [20]. DREAM has been partially validated and it has been criticized about the accuracy of their estimations and the reproducibility in several case studies with different characteristics [39]. PHED is focused on farming systems in industrialized countries, its determinants evaluate the exposure during pesticide applications made by tractor and with motorized equipment, there is no distinction of the pesticide transport processes such as emission, transfer and deposition.…”