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Aquatic Ecotoxicology

Brexit: Transition period

The UK has now left the EU. Your health and safety responsibilities have not changed in the transition period.

Find the latest information on our Brexit pages


The requirements for an aquatic risk assessment depend on the type of authorisation you are seeking as the methods to calculate exposure vary (see the Environmental Fate web pages for further detail).

EU (Annex 1 listing) - Use FOCUS (including Step 4 if required)

Central zone assessment - Use FOCUS (to Step 3 as risk mitigation is determined by Member states)

UK only assessment and UK national addenda to a central zone assessment - Do a UK specific spray drift and drainflow assessment

Current Guidance Document

Guidance on tiered risk assessment for plant protection products for aquatic organisms in edge-of-field surface waters (EFSA Journal 2013; 11(7):3290)

Previous Guidance Document

Guidance document on Aquatic Ecotoxicology in the frame of the Directive 91/414/EEC (SANCO/3268/2001 rev.4, final, 17 October 2002)

Additional Guidance on Specific Issues

Products with multiple active substances

Currently, the long-term risk to aquatic life from products that contain more than one active substance is assessed using data on the individual active substances. This is based on the assumption that the formulation will break down into its component active substances once it enters the water, ie the two active substances will have different fate and behaviour profiles.

It should be noted that if the product contains more than one active substance and the route of entry is via drainflow then the potential additive effects should be considered. Similarly if the active substance and metabolite(s) are likely to co-occur then this risk should also be considered. It should be noted that the fate and behaviour of the individual active substances will determine the degree of co-occurrence and should be considered in the risk assessment. In addition, it should be considered whether the risk is being driven by one active substance. If all the active substances within the formulation pass the risk assessment with a margin of safety then the need for further assessment will be limited.

Worked example of a buffer zone assessment for spray drift for a horizontal boom sprayer in field crops

A worked example is provided showing how the aquatic buffer zones for crops on a product label are calculated under the interim extension of the LERAP scheme. A calculator is also available for producing the Predicted Environmental Concentration in surface water (PECsw) and this is also available on this website below.

Spreadsheet to help with risk assessment

CRD is not responsible for the accuracy or use of any endpoints derived using the following

To download the spreadsheets, right click on the link and select 'Save As...' or 'Save Target As...' from the menu. You can then save the spreadsheet to your computer.

Predicted Environmental Concentration Calculator for spray drift in field crops

Calculator for producing the Predicted Environmental Concentration in surface water (PECsw) for spray drift for a horizontal boom sprayer in field crops


Updated 2016-07-12