An example to illustrate the potential use of probabilistic modelling to estimate operator exposure to pesticides

To illustrate the potential for probabilistic simulation modelling of opera tor exposure a probabilistic model was constructed using the draft EUROPOEM II database. The model also incorporated actual pesticide use data. Althou gh the EUROPOEM II database is not complete, and the resulting simulation h as to be regarded as only provisional, the data were sufficient to illustra te some of the principles involved, The model was constructed using nonpara metric empirical input distributions. Associations were observed in the inp ut exposure data and were reflected in the model. The exposure and usage da ta were all variable and showed highly negatively skewed distributions and the technique avoided concerns about having to define single representative values for point estimates. Increasing the number of iterations improved t he stability of the output, but as expected, resulted in higher exposures b eing predicted due to a combination of rare events. Analysis of the inputs for individual iterations giving high results indicated that, in this examp le, these were due to unrepresentatively high input values for inhalation e xposure. Simulations that excluded these values were more stable and showed lower exposures, illustrating the need to ensure the validity of the input distributions. Crown Copyright (C) 2001 Published by Elsevier Science Ltd on behalf of British Occupational Hygiene Society, All rights reserved.