Use of TTC Cramer Class III (CCIII) value at step 5 of the groundwater (gw) metabolite relevance assessment of PPPs


The Chemicals Regulation Division (CRD) of HSE has developed a paper describing the use of the TTC CCIII value (1.5 µg/kg bw/d) for gw metabolites at step 5 of the relevance assessment of PPPs, when there is no other suitable data to derive metabolite-specific acceptable daily intakes (ADIs).


HSE considers it to be a scientifically valid approach which is consistent with the SANCO (2003) gw relevance assessment guidance (PDF)(the EU guidance currently applicable in GB relevant to this specific aspect of the evaluation).


The paper is available to download from our Pesticides website:


TTC and groundwater metabolites (PDF)


HSE is committed to minimise unnecessary animal testing, with in vivovertebrate studies being seen as the last resort (Art. 62 of Regulation (EC) No 1107/2009). For gw metabolites which are not structurally or toxicologically similar to the parent active substance or for which a read-across from a data-rich analogue is not possible, the SANCO (2003) guidance requires at step 5 the generation of repeated dose toxicity studies in experimental animals to establish metabolite-specific ADIs for the subsequent dietary risk assessment.


The paper developed by HSE describes how the TTC CCIII value can be used as an alternative to studies in experimental animals, leading to a significant reduction in unnecessary animal testing. However, it should only be used when it is considered scientifically justified, in line with the most recent EFSA (2019) guidanceon TTC.


HSE deems that such an approach provides a thoroughly considered, scientifically supported and justified precedent, which leads to reduction of unnecessary animal testing, without compromising on protection goals.


The approach was fully supported by the independent scientific advisory committee, the Expert Committee on Pesticides (ECP).


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~sHSE, 4 February 2022