Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment for plant protection products

Abstract

Regulation (EC)No 1107/2009 ensures that the residues of plant protection products (PPPs), consequent to application consistent with good plant protection practice and having regard to realistic conditions of use, shall not have any harmful effects on human health. In 2010, the EFSA Panel on Plant Protection Products and their Residues (PPR) prepared a Scientific Opinion on "Preparation of a Guidance Document on Pesticide Exposure Assessment for Workers, Operators, Residents and Bystanders", which highlighted some inconsistencies between the approaches adopted by regulatory authorities. Therefore, the PPR Panel proposed a number of changes to those practices in use (e.g. routine risk assessment for individual PPPs should continue to use deterministic methods, and a tiered approach to exposure assessment remains appropriate; there is a need to introduce an acute risk assessment for operators, workers and bystanders where PPPs are acutely toxic; for acute risk assessments, exposure estimates should normally be based on 95 th percentiles of relevant datasets, whereas, for longer term risk assessments, the starting point should be a 75 th percentile). To prepare a Guidance Document, an ad hoc working group was established to revise all available data and procedures to perform the operator, worker, resident and bystander risk assessment. In addition to the data reported in the PPR opinion, further data were made available to the working group which were analysed and considered. The opinion also identifies those scenarios for which exposure estimates are least satisfactory, and makes recommendations for further research that would reduce current uncertainties. An exposure calculation spreadsheet, reflecting the Guidance content, is annexed to this Guidance Document, to support stakeholders in performing the assessment of exposure and risk.

How does exposure to pesticides vary in space and time for residents living near to treated orchards?

“…Four pathways of exposure are considered in the standard EU risk assessment for residents which uses a model of residents living 8 m downwind from the middle of the last row in orchard crops (EFSA 2014); these pathways are (i) spray drift resulting in direct exposure via dermal penetration and inhalation; (ii) spray drift causing deposits on the ground and other surfaces leading to dermal exposure; (iii) vapour dispersal leading to inhalation of airborne pesticides following volatilisation from residues on soil and/or the treated crop; and (iv) entry into treated crops causing exposure through direct contact with surface residues. Spray drift decreases very rapidly with distance from the treated field (Rautmann et al 1999) and preliminary modelling showed that direct dermal and inhalation exposure from spray drift were insignificant contributors to total exposure for residents living 100 or 1000 m from the treated area due to the combination of rapid fallout of spray droplets from the air with increasing distance from the site of application (Sarigiannis et al 2013; van de Zande et al 2014), and short duration of exposure.…”

“…The EFSA assessment for residents’ exposure to pesticides is currently based on the highest time-weighted average exposure for the first 24 h after application via inhalation from vapour and 2 h of dermal exposure to surface deposits (EFSA 2014). The FOCUS Air group considered that the largest exposure would occur within a 24-h period following application when taking into account the effects of dilution and dispersion of residues due to changing meteorological conditions (FOCUS 2008).…”

“…Indirect dermal contact with contaminated ground was estimated from the equations provided by EFSA (2014) for systemic exposures of residents via dermal routes. Where parameters were set to default values, these are listed in Table S1.…”

“…Concentrations in air derived from the air dispersion modelling were converted into individual exposures according to EFSA (2014): …”

“…In Europe, the estimation of exposure to pesticides for operators, workers, residents and bystanders is underpinned by the guidance of EFSA (2014). However, sparcity of data on concentrations of volatilised pesticides in air has been noted as a limitation on exposure assessment (Butler Ellis et al 2010), as has a general lack of research into methods for estimating exposure and risk to the general public (Coscolla et al 2017).…”