Aggregate exposure to pesticides from dietary and non-dietary exposure: A UK case study for residents, bystanders and spray operators

摘要

Exposure to pesticides can occur from multiple sources and distinct sub-populations can be affected very differently. In the EU Horizon 2020 project Euromix, new tools are being added to the Monte Carlo Risk Assesment (MCRA) software which allow calculation of aggregate exposure in a very flexible way. An external model, designed to calculate a particular source of exposure, can be run to generate simulated non-dietary exposures. The results can then be integrated with the dietary calculations of MCRA. We present a particular example based on the BROWSE model (Bystander, Resident, Operator and Workers Exposure), which has various built-in scenarios for different populations, spray application types and crops. BROWSE generates probabilistic output to represent variation in exposure conditions. By default, many assumptions such as scenario definitions and input parameters have conservative default values. However, by repeated runs of the model with realisations of actual spray amounts we aim to produce a more realistic exposure distribution. The annual UK pesticide usage survey (PUS) provides detailed field level information about real combinations of pesticides applied to crops at field level. It includes the main crops grown in the UK including arable, orchard, outdoor vegetable, soft fruit and covered crops. The examples presented will illustrate how the new probabilistic aggregate model implemented in MCRA, as part of the Acropolis and Euromix projects, can generate a detailed distribution of exposures to multiple pesticides. BROWSE is used to generate a matrix of exposure simulations representing population variation for defined sub-populations. This matrix is then linked to MCRA and aggregated with the relevant dietary exposure for the UK population to produce total exposures. The resulting MCRA outputs highlight the relative sources of exposure, and the most significant pesticides. An important potential use of the results is to prioritise testing of chemical mixtures to those that occur in real exposures.