How non-standard studies and their weight of evidence evaluation may be used within Environmental Quality Standards derivation: a case study with endocrine disrupting assessment of tebuconazole
Résumé
Within the Water Framework Directive Common Implementation Strategy (WFD CIS) context, the derivation of Environmental Quality Standards (EQS) is framed by recommendations given in the European Technical Guidance Document for Deriving EQS (TGD EQS, E.C., 2018). This guidance recommends the use of data that are deemed relevant and reliable. Those are most often generated using standardised test methods, but not confined to standard studies and species. The concern raised by endocrine disruption should be tackled in diverse regulatory frameworks, among which the WFD. In this context, endocrine disruption (ED) is quoted several times as an issue in the TGD EQS but recommendations as this regards are not prescriptive. Our study attempts to assess how far can the ECHA/EFSA Guidance for the identification of endocrine disruptors (ECHA/EFSA, 2018) and its weight of evidence approach may be used within the context of the derivation of EQS for tebuconazole.The work consisted in (i) gathering ED toxicity data for aquatic wildlife and mammals not included in the initial dataset underlying the current EQS, (ii) assembling them in a database as lines of evidence of toxicity adressing endocrine activity in order to assess as rigorously as possible the ED potential of tebuconazole and finally (iii) analysing these data to evaluate how far they allowed to improve reliability of the current EQS for tebuconazole.The collection of data allowed to assemble more than 200 lines of evidence consisting in vivo mammals data (52%), in vivo wildlife data (34%) and in vitro mechanistics data (14%).The assessment did not allow to conclude on the ED potential of tebuconazole for wildlife strictly applying the guidance, whereas this ED potential was demonstrated for mammals for which at least two modes of action analysis enabled to conclude on the link between endocrine activity and adversity.Wildlife toxicity assessment would need more in-depth analysis, inter alia to collate and analyse invertebrates toxicity data in order to assess other taxa than fish and amphibians which are already well-represented in the dataset.This analysis allowed implementation of the weight of evidence approach of non-standard toxicity test within the assessment in order to strenghten relevancy and reliability of its EQS. It gives a good opportunity to evaluate how ECHA/EFSA guidance may be used in another regulatory context for which it is meant and allows highlighting the pros and cons of this exercise.