Implementation and evaluation of the fluorescent tracer technique in greenhouse exposure studies

Knowledge of the level of exposure is important for health risk estimation and risk management. Recently, the occurrence of dermal exposure in many situations has been recognized and estimated to be relevant for worker health. Dermal exposure measurement techniques are therefore needed and several approaches have been taken to assess this type of exposure. The purpose of the present study was to apply and evaluate the fluorescent tracer technique, being one of the most promising and innovative techniques to estimate dermal exposure. The image acquisition is fully calibrated and validated. The most significant aspects of the image analysis process are validated in laboratory settings. The system is applied in a field study to estimate dermal exposure of operators and harvesters in greenhouses, while chemical analysis of clothing exposure is also performed. For operators, the correlation coefficient between the active substance (propoxur) and the fluorescent compound (Tinopal) was 0.92, and for harvesters 0.85. It is concluded that the variability in the analytical technique used is insignificant with respect to the variability in exposure within and between workers. Instead of improving the measuring technique, one might better lower the variability by measuring, for instance, a larger number of workers and/or by standardizing work procedures. The fluorescent tracer technique, being a fast method to estimate dermal exposure, enables the estimation of larger numbers of individuals. Furthermore, the qualitative use of this technique can lead to a more efficient sampling strategy since the exposed body area to evaluate can easily be visualized and selected.