Exposure estimates epidemiological strategies

Despite the fact that few epidemiological studies with quantitative exposure assessment data are available for pesticide exposure, more insight is now present on how the optimal exposure assessment strategy might look. In particular, the use of determinants of exposure studies, as reviewed recently, and their application in health-based exposure estimation, seems a promising approach that can solve many of the problems associated with pesticide exposure assessment in agriculture. This approach will be of use in both occupational and domestic epidemiological studies on this topic. 

Exposure assessments may be conducted for one of four purposes hazard evaluation leading to appropriate control efforts, monitoring to ensure compliance with workplace standards, dose-response characterization within the context of epidemiological studies, and estimation of dose or uptake for risk assessments. Assessment strategies and measurement techniques will differ depending on the purpose at hand. 

The combination of the health-relevant time-window and the toxicokinetic properties of the agent of interest determine the optimal exposure assessment strategy. Dioxin, a contaminant of chlorophenoxy herbicides and fungicides, has a relatively long biological half-life, estimated at about seven years and is measurable in serum. Serum measurements of dioxin are therefore relatively stable, and simple first-order kinetics have been used to back-estimate serum dioxin levels on the basis of an occupational history. Such exposure data have been used quite successfully in epidemiological analyses of cohorts of pesticide producers (Hooiveld et al, 1998). 

Despite the usefulness of exposure models to estimate exposure of population in different scenarios, the necessity of quantitative exposure data either for registration or for epidemiological studies, is widely recognised [19]. The quantification of the exposure is a critical issue and can be addressed from many different points of view. It is not always easy to select the correct strategy. Biomarkers for monitoring pesticides, among other chemicals. 

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