EFSA aquatic ecotoxicology guidance incorporates a decade of scientific developments

Safeguarding consumers, animals and the environment from risks related to pesticides is a core part of the European Food Safety Authority’s (EFSA) work. The Authority’s newly revised risk assessment scheme on pesticides and aquatic organisms – so-called aquatic ecotoxicology - makes a major contribution to this goal. Dr Theo Brock, an expert member of EFSA’s Panel on Plant Protection Products and their Residues (PPR), explains why the Authority was asked to update the risk assessment guidance and he outlines the new techniques that will help risk assessors and decision-makers protect fish, amphibians, invertebrates and aquatic plants when pesticides are authorised.

Dr Theo Brock
Expert member of EFSA’s Panel on Plant Protection Products and their Residues (PPR)

Why was it necessary to revise the former guidance on aquatic ecotoxicology?

Dr Theo Brock: The introduction of new EU legislation for placing pesticides on the market and a series of scientific developments meant that the old guidance needed to be looked at again.  These regulations include new legal requirements on the core data to be provided by applicants. For example, with regard to aquatic invertebrates the old legislation only required data on a tiny crustacean called Daphnia, as this could be used as a safety indicator for all species in this type of aquatic organism. However, it is now necessary to provide data on more species because Daphnia are not sensitive to some of the new insecticides that have been authorised since 2002.

Risk assessment techniques have also advanced over time and this guidance incorporates a decade of scientific developments. A lot of new information has emerged on how to implement specific protection goals and how to link exposure to effects on aquatic organisms – which is the key concept of this guidance.

Will the guidance promote a standardised assessment approach to aquatic ecotoxicology across Europe?

T.B.:  Yes, an important element of the guidance is that it will promote a harmonised risk assessment approach. The previous guidance document allowed risk assessors more scope to make individual interpretations of findings. However, as the European legal framework now calls for mutual recognition of risk assessment of pesticides among Member States, risk assessors should ideally use the same approach.

What innovations have been developed in the guidance document?

“…the guidance document we have presented today marks the start of a project that will transform the way we assess the risk posed by pesticides to aquatic organisms in Europe.”

T.B.: The most significant innovation in the guidance document is the further development of a tiered risk assessment approach – and in particular the use of higher tiers. These use experimental approaches to more accurately evaluate the threat to different types of aquatic organisms. The extent to which relevant data are available is central to being able to apply higher tier techniques. For example, in tier 2 we outline techniques for pooling data to facilitate their interpretation. The availability of further data allows scientists to use a method called species sensitivity distributions (SSDs) to derive pesticide concentrations where research has shown there is a negligible effect on the aquatic organisms concerned.

For tier 3 assessment, artificial ponds or streams are used as model ecosystems. These enclosures, simulating freshwater ecosystems at the edge of fields treated with pesticides, are large enough to study impacts of different exposure scenarios on most aquatic organisms but less so for fish. Using this method, we can calculate the pesticide concentrations that pose a low risk to aquatic organisms for both the ecological threshold option (ETO) and the ecological recovery option (ERO) – the two effect assessment schemes outlined in the guidance to assess the effect of pesticides on aquatic organisms.

Why has EFSA’s new guidance proposed both the ecological threshold option (ETO) and the ecological recovery option (ERO)?

T.B.: The decision to develop two options was taken following consultation with risk managers from Member States and the European Commission. As multiple pesticides can be used on the same crop, experts recommend that the ETO method, which demands a higher level of protection, may be preferable to the ERO assessment scheme. But the guidance document recommends the development of both options as this allows risk managers in Member States to select and develop the most appropriate system for their national programmes.

Will EFSA be carrying out more work on assessing the risks to aquatic organisms from pesticides?

T.B.: Yes, the guidance document we have presented today marks the start of a project that will transform the way we assess the risk posed by pesticides to aquatic organisms in Europe. Following on from this, EFSA’s PPR Panel is scheduled to deliver a scientific opinion to assess the effects of pesticides on sediment-dwelling aquatic organisms by the end of next year. While the new guidance presents a basic methodology for aquatic organisms that live in sediments, the future opinion will develop a full risk evaluation scheme. A third output covering mechanistic effect modelling approaches in aquatic risk assessment is also planned for publication in 2016.

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