Aged Sorption

Achieving an acceptable regulatory risk assessment using first-tier approaches with standard substance data sets can be problematic in the case of some substances. This has led to several higher-tier refinement approaches as described by the FOCUS groundwater workgroup in 2009, one of the principal approaches being to investigate the potential for the strength of soil sorption of a substance to increase over time (aged sorption). A detailed guideline on how aged sorption studies for pesticides should be conducted, analysed and used in regulatory assessments has now been published on the EC website, and studies can be included in submissions from 1 April 2021.

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Enviresearch and Fera Science collaboration

Together with other collaborators, Enviresearch/Fera have been working with the Chemicals Regulation Division (CRD) of the UK’s Health and Safety Executive, the UK’s competent authority for plant protection products, for more than ten years, developing and revising the new guidance for aged sorption. This development has included the design of the appropriate experimental protocol, standardisation of deriving the required parameters from the experimental data and how the parameters are subsequently used during exposure modelling. Fera and Enviresearch have extensive experience in providing the best regulatory and risk assessment services in Europe for the global chemical industry, with a highly dedicated and experienced group of experts who are at the cutting edge of science underpinned with the power of Fera’s experimental excellence.

Fera and Enviresearch have teamed up to provide a comprehensive service that covers all requirements for aged sorption, including a webinar, which can be viewed here. Follow this link for information on our joint services.

Aged sorption services

The study is performed as an incubation study equivalent to OECD guideline 307, but with an additional extraction step using 0.01 M CaCl2-solution. The data could therefore be obtained during the standard degradation studies with little extra effort. However, the guidance requires that the standard equilibrium sorption studies are also performed on the same soils, so it makes sense to plan ahead. Parameters are derived by fitting the aged sorption model, for example, in PEARLNEQ. The guidance explains how to combine the aged sorption parameters with sorption and degradation endpoints from tier 1 for the groundwater assessment.

Our services

  • Review of existing data
  • Development of an aged sorption strategy
  • Delivery of required experimental studies
  • Modelling and interpretation of the resultant data
  • Combination with tier 1 endpoints
  • Higher-tier groundwater assessment

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