Guidance on Estimating Environmental Exposure (PECs)

When assessing the likelihood and degree of environmental exposure from pesticide active substances and their metabolites a number of key elements need to be considered including:

• their mobility and transport in the environment
• their route and rate of degradation
• the pesticide use rate
• environmental characteristics

To harmonise the calculation of PECs in the EU PPP regulatory framework, the FOrum for the Co-ordination of Pesticide Fate Models and their Use (FOCUS) was established.  This forum have produced a number of environmental exposure modelling tools and a set of standardised realistic worst-case scenarios (i.e. combination of climate and weather data) to provide realistic worst case pesticide exposure estimates in various environmental compartments following the intended use of the product.  Further information on the FOCUS models can be obtained from the FOCUS DG SANTE (ESDAC - EU Commission) website.  Guidance on how to derive reliable environmental degradation half-lives (DegT₅₀) for modelling and on how to correctly parameterise the groundwater and surface water models can be found in the ‘Related Content’ section of the aforementioned website.  These documents must be read in conjunction with the following EFSA guidance documents:

EFSA Guidance/Opinions

• EFSA Guidance Document for evaluating laboratory and field dissipation studies to obtain DegT₅₀ values of active substances of plant protection products and transformation products of these active substances in soil (2014)

• Scientific Opinion on the report of the FOCUS groundwater working group (FOCUS, 2009): assessment of lower tiers (2013)

• Scientific Opinion on the report of the FOCUS groundwater working group (FOCUS, 2009): assessment of higher tiers (2013)

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