EFSA concern on the effect of water treatment processes on the nature of pesticide residues

August 12, 2016

Since the implementation of the regulation 1107/2009 a few years ago, the European Food Safety Authority (EFSA) has reviewed and issued several conclusions on the peer review of the risk assessment of many pesticide active substances on behalf of the European Commission (EU).   Through these conclusions, EFSA has provided recommendations either for inclusion or non-inclusion of the active substance in Annex I.  A search on the EFSA webpage reveals that out of approximately twenty-two conclusions issued between January and July 2016, about fifteen contained a concern regarding missing information on water treatment.  In these conclusions, EFSA has been citing failure to demonstrate the effect of water treatment processes on pesticide residues as a data gap.  EFSA has consistently included the following statement in their conclusions: 

“The data available on environmental fate and behaviour are sufficient to carry out the required environmental exposure assessments at the European Union (EU) level for the representative uses, with the notable exception that the information was not available regarding the effect of water treatment processes on the nature of residues that may be present in surface water and groundwater at the point of abstraction for drinking water purposes. This results in it not being possible to finalise the consumer exposure and risk assessments.” 

The data gap identified by EFSA arises from Article 4.3(b) of regulation 1107/2009, which states that one of the criteria and condition for approval of plant protection products is that: “it shall have no immediate or delayed harmful effect on human health… …directly or through drinking water (taking into account substances resulting from water treatment)…”.  However, no test methods or guidance documents on how to address substances resulting from water treatment are available.

This issue was considered in the US and the EPA held a Scientific Advisory Panel (SAP) in September of 2000 in a session titled, “Progress Report on Estimating Pesticide Concentrations in Drinking Water and Assessing Water Treatment Effects on Pesticide Removal and Transformation: A Consultation.”  Among other issues, the question of disinfection processes, particularly chlorination, and their potential effects on pesticides was addressed by the panel (Question 2.3) was of particular concern.  The panel recommended to the Office of Pesticide Programs (OPP) to have on staff, scientists that are “familiar with water treatment techniques, to predict the behavior of pesticides in water treatment processes.”  They proposed the need for identification of potential products that could be formed and the conditions under which they might be formed.  In addressing this question, the panel provided an overview of the classes of compounds to be particularly concerned about, as one may be able to address the issue through scientific reasoning or structural analysis or modeling argument for some molecules.  For some other molecules however, it may be prudent to address the issue by performing bespoke testing mimicking some aspects of water treatment processes like disinfection with chlorine.

It is not clear at the moment whether or not experimental studies will be required in the long run to address this issue. What can be said is that companies would be wise to develop strategies now that address this anticipated data gap for their compounds.

To discuss these and other testing strategies in detail, contact:

Dr. Kalumbu Malekani
+1 508-295-2550


About The Author | Dr. Kalumbu Malekani

Dr. Kalumbu Malekani is the North American Technical Director. He holds an M.Sc. and Ph.D. in Environmental Soil Science and Applied Analytical Chemistry. He is a member of many scientific and professional associations and has authored numerous publications, technical reports, position papers, and dossiers for global registration submission. He served for five years as Smithers Viscient's Director of Environmental Fate and Metabolism, has over 20 years of experience in CRO, academia, and regulatory pesticide fate and transport research, and is recognized by clients and regulatory professionals as an industry spokesperson, strategist, and a skilled hands-on scientist.

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