REACH regulation substance evaluation involves an assessment of substance Persistence, Bioaccumulation and Toxicity (PBT) properties. Substances can be categorised as PBT (persistent, bioaccumulative and toxic) or very persistent and very bioaccumulative (vPvB). PBT assessment is required for any substance being manufactured or imported in quantities >10 tonnes per annum, and was developed by ECHA to identify substances that might be expected to persist for a long time in the environment and accumulate to high levels via the food chain, potentially causing adverse effects that are difficult to predict. The criteria for PBT/vPvB properties are set out under Annex XIII of the REACH legislation and detailed in Chapter R.11. Additional criteria for screening substances with properties that are indicative of “P” or “B” are also detailed in Chapter R. 11.

The evaluation of PBT/vPvB properties requires the use of all available screening and assessment information available for a substance, which is then considered using a weight of evidence approach. This means that all relevant data from in vitro tests, data from human and animal studies, QSAR and read across, and monitoring and modelling studies should be included. The quality and consistency of the data are given appropriate weight and then considered together in a single weight of evidence determination.

wca have conducted PBT assessments for a range of substances including chemical substances of Unknown or Variable Composition, Complex Reaction Products and Biological Materials (UVCBs), and are experienced in responding to questions from ECHA on this topic. Our scientists have also influenced the recent updates to the PBT/vPvB guidelines and the weight of evidence approach by contributing to key recent publications on this topic. For further information, see blogs on the PBT weight of evidence approach and terrestrial bioaccumulation.

Our services include:

  • Determination of the relevant compartment of concern for a substance
  • Data gap assessment
  • Proposal of testing strategies following the general approach of concluding on “P”, then “B” and finally on PBT
  • Commissioning of relevant testing, study monitoring and interpretation of the results in the context of PBT assessment
  • IUCLID entry for relevant data
  • Weight of evidence assessment for PBT assessment under REACH
  • Support during Substance Evaluation, including preparation of comments in response to Draft Decision Letters and discussion with Member States and ECHA
  • PBT assessments for substances not considered directly under REACH but meeting the relevant screening criteria for PBT assessment under other legislation including veterinary medicines, pharmaceuticals and biocides.

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