Aquatic Ecotoxicology

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)

The current guidance document is intended to be used for authorisation of active substances as well as for plant protection products. It provides the scientific background for the risk assessment to aquatic organisms. The UK specific aquatic risk assessment involves a spray drift and drainflow assessment using aquatic toxicity endpoints and Predicted Environmental Concentration (PEC) values calculated by Environmental Fate (also see the Environmental Fate web pages for further detail).

Aquatic Toxicity Studies

OECD guidelines for aquatic toxicity studies are available on the OECD website.

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)

Guidance on Specific Issues

Formulation guidance

For applications considered under Regulation 1107/2009 (as it applies in Great Britain and Northern Ireland) the formal requirements for Ecotoxicology formulation testing are laid out in Part A, Section 10, Annex to the Regulation 284/2013. UK specific formulation guidance is also available as outlined in the HSE formulation guidance.

This HSE guidance provides advice on the need for ecotoxicology formulation studies and their use in risk assessment, along with how to consider the combined risk for relevant groups. Formal sections of the data requirements and existing guidance documents are presented together with additional guidance. Applicants are advised to read this document before deciding on a formulation testing strategy.

Products with multiple active substances

When a product has more than one active substance, the potential additional risks to aquatic organisms must also be considered. Reference can be made to the HSE formulation guidance. Notes on some common queries are below:

It is noted that 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.

However, 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

HSE 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 2021-08-10