Piacenza Symposium on Pesticide Chemistry
In September, Enviresearch attended the XVII Symposium on Pesticide Chemistry, which is held once every four years at the Agricultural University of Piacenza, Italy. The conference is one of the main gatherings for environmental science of pesticides, and a platform for academia, industry and authorities to meet and discuss the latest issues and developments. The focus of this year’s event was ‘Advances and New Challenges’. Our environmental fate specialist Wendy van Beinum shared some of the highlights from this symposium.
Trifluoroacetic acid (TFA) formation from pesticides
There is a growing concern across Europe on environmental levels of trifluoroacetic acid (TFA), and the potential contribution of pesticides as a source. TFA is known to be very persistent and mobile, and formation from pesticides could potentially result in high concentrations in groundwater. Groundwater monitoring data from Denmark showed that TFA was detected in 38% of the wells. The Geological Survey of Denmark and Greenland (GUES) performed a laboratory test to measure the potential of TFA formation from seven pesticides containing the ‑C-CF3 group, during degradation in soil. The results showed that TFA formed gradually and continually during the 52-week study, reaching levels between 0.4 and 10.7% of the available C‑CF3 of the concerned pesticide.
Transformation products from drinking water treatment
Representatives from the plant protection industry presented the new guidance on transformation products from drinking water treatment. The guidance presents new challenges, as any substance exceeding the threshold for PEC in groundwater or surface water could potentially trigger extensive testing on genotoxicity and toxicity. This includes metabolites that were considered non-relevant in groundwater, and actives/metabolites that passed the lower tiers of the risk assessment due to low toxicity for aquatic organisms. The guidance allows for zonal-specific dilution factors for abstraction from surface water, but not for groundwater, and the dilution factors are generally considered overly conservative.
CLP hazard criteria for persistent and mobile substances
The new CLP hazard criteria for persistent & mobile substances are causing concerns for industry. Many pesticides fall in the category ‘persistent’ due to slow degradation in water, despite degrading more rapidly in soil. This is compounded by the conversion of DT50 values to 12°C before comparison with the criteria. For the assessment on mobility, the criteria only considers the sorption KF,OC and ignores other factors that influence leaching behaviour such as nonlinear sorption, degradation and variable environmental conditions. It is then necessary to rely on the Weight-of Evidence framework to overrule the simplistic and conservative initial assessment. The Fraunhofer Leaching Calculator was proposed for a more realistic classification of mobility.
Updates on VFSMOD for runoff mitigation
The conference was preceded by a workshop to discuss the latest developments on the VFSMOD model in SWAN, working towards acceptance of the model at EU level. VFSMOD is a mechanistic model for predicting the runoff reduction by vegetated filter strips enhancing infiltration and trapping of sediment particles. The workgroup had addressed some uncertainties that were flagged by authorities, such as implementing subsurface flow, revision of the default mean particle diameter of eroded sediment, and spatial analysis of the soil textures across the FOCUS regions to ensure the model is protective for all soils represented by the scenarios. The report will be made available to EFSA and EU authorities for independent review.
As always, the conference was buzzing with interesting discussions and exchanges of ideas, and we were looked after magnificently by the conference organisers. Get in touch if you want to discuss any of these topics or hear what we can do to help.