Assessment of Dermal Pesticide Exposure with Fluorescent Tracer: A Modification of a Visual Scoring System for Developing Countries

Abstract

A semi-quantitative dermal exposure assessment method based on visual observations of fluorescence images was presented by Fenske in 1988. We adapted the method to Nicaraguan working conditions and evaluated its performance. Thirty-two farmers applied chlorpyrifos and methamidophos marked with Tinopal CBS-X(R). Skin fluorescent depositions were observed with a portable UV lamp in a foldaway darkened room. We modified the two components of the original system-extent by weighting the size of exposed body parts according to total body surface and intensity by establishing criteria for reading the fluorescence images. This resulted in body segment scores (BSSs) for specific body parts as well as two summary measures, contaminated body area (CBA) as the percentage of contaminated skin in relation to total body surface and total visual score (TVS) as an overall score combining extent and intensity of contamination. The scoring of intensity was evaluated with quantitative chemical residue analyses. Hands were the most frequently contaminated, and the back had the highest BSS. The CBA ranged between 1 and 66% and the TVS between 0.5 and 270. The farmer with the highest TVS scored 60% of the maximum possible. Residues increased with increasing fluorescence intensities with some misclassification. Fluorescent images reflected work practices and contamination mechanisms. In conclusion, the visual score, as modified by us, provides information on the body segments most contributing to dermal exposure and degree of skin contamination during pesticide applications. Fluorescence patterns reflect exposure routes. The system is low-cost and practical for developing countries. Further improvements are recommended.