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3) Exclusion of non-relevant metabolites from groundwater indicator assessment

We excluded non-relevant metabolites (nrM) from the calculation of exceedance rates in groundwater. This is in line with the 2006 Groundwater Directive, where the quality standard for pesticides of 0.1µg/l does not apply to nrM.

However, recent work towards a Europe-wide study recommends inclusion of nrM in Annex I of the Groundwater Directive, with the need to establish harmonised definition and assessment of nrM and to set quality standards in line with quality standards of Groundwater Directive.

Should nrM be included in the indicator? If so, what quality standards should apply?

Previous comments

Bert Leemans (invited by Caroline Whalley) 02 Aug 2021 14:26:13

There is a wide variety between countries in identifying nrM. Not all countries apply the same assessment methods for identifying nrM.
Volker Laabs (invited by Caroline Whalley) 12 Aug 2021 15:21:09
- Last paragraph: As mentioned in paragraph one, there currently is no EU-wide quality standard established for nrMs in groundwater. This may or may not change in the current process of Annex I/II revision of the EU Groundwater Directive. Some MSs have defined threshold values for nrMs in drinking water (e.g., Germany, Austria, The Netherlands), but for general surface or groundwater this was not the case yet. Therefore, we propose to exclude nrMs from the current exceedance value calculation.
- In case an EU-harmonized limit value for nrMs in drinking or groundwater is needed, we propose to use the TTC-based threshold value of 9 µg/L for all nrMs (Cramer Class III substances, default WHO methodology for drinking water guidance values – 20% allocation of ADI to drinking water; see also Laabs, V., Leake, C., Botham, P., and Melching-Kollmuß, S. 2015. Regulation of non-relevant metabolites of plant protection products in drinking and groundwater in the EU: Current status and way forward. Regul. Toxicol. Pharmacol. 73, 276-286).
mohauvol (Volker Mohaupt) 07 Sep 2021 13:01:41

Comment from UBA Germany, Unit Pesticides:

We suggest to consider non relevant metabolites of pesticides with a threshold value of 1 µg/L. As emerging contaminants, non relevant metabolites shall be considered for precautionary reasons: Many of them are very mobile and persistent, difficult to analyse, hardly removable from water resources and with a scarce data base compared to active substances. In some cases, non relevant metabolites were classified as relevant later on or showed unexpected effects (e.g. transformation to carcinogenic compounds during water treatment, Schmidt and Brauch (2008): <a href="https://pubmed.ncbi.nlm.nih.gov/18800499/" rel="nofollow">https://pubmed.ncbi.nlm.nih.gov/18800499/</a>). Also, the awareness for non relevant metabolites is rising in many member states. For instance, the new drinking water directive demands the member states to define a guide value for non relevant metabolites. Implications for other directives and national law are expected. In Germany, a threshold value in groundwater regulation was discussed and supported by various stakeholders (but finally not implemented, however at least monitoring duties were established in the same law).

Indeed, there is no legislative threshold or limit value yet. However, in plant protection regulation the value of 10 µg/L according to SANCO 221/2000 guidance (<a href="https://ec.europa.eu/food/system/files/2016-10/pesticides_ppp_app-proc_guide_fate_metabolites-groundwtr.pdf" rel="nofollow">https://ec.europa.eu/food/system/files/2016-10/pesticides_ppp_app-proc_guide_fate_metabolites-groundwtr.pdf</a>) is applied for the groundwater risk assessment of pesticides on EU level and, in some member states, as exclusion criteria for the authorization of plant protection products. It is basically common sense that concentrations above 10 µg/L for non relevant metabolites in groundwater are not acceptable. However, a threshold of 10 µg/L is not sufficient for the analysis of trends and the precautionary consideration of risk mitigation measures: Leaching to groundwater underlies high retardation in soil and there is hardly any further degradation in the groundwater bodies. Therefore, elevated concentrations cannot or only slowly may be reduced by measures or reduced application. Based on the established German concept of Health Related Indication Values (HRIV) UBA suggests to use the value of 1 µg/L. This value is also very close to the threshold of 0.75 µg/L as trigger for deeper assessment according to SANCO 221/2000. This value is also applied by some EU member states for their authorization of plant protection products, e.g. Denmark and Italy.

Considering these trends and discussions it would be adequate to proactively include non relevant metabolites in the pesticide indicator.
mohauvol (Volker Mohaupt) 07 Sep 2021 15:05:29

Comment from German Federal State Schleswig-Holstein (repeated from 1. Key Messages):

The indicator concept was tested with a dataset derived from the WFD monitoring of the German Federal State Schleswig-Holstein. The results were:

- Groundwater: We acknowledge, that the indicator does not use “Non relevant Metabolites” since there is no agreed EU threshold. In Germany these metabolites are assessed with “Health Related Indication Values (HRIV)“ specialized for each metabolite. Exceedances of these threshold values for the non-relevant metabolites are the main causes of the poor status in the group of plant protection and degradation products.

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