European legislation requires all veterinary medicines to undergo an environmental risk assessment (ERA) based on their expected use. The ERA is an evaluation of the possible hazards to the environment posed by a veterinary medicine. The European Medicines Agency (EMA) considers the environmental risks of a veterinary medicine in its benefit/risk assessment and ​​​provides guidance to help marketing authorisation applicants assess the environmental impact of their medicine and implement risk mitigation measures. 

The purpose of the ERA is to:

  • identify potential environmental hazards and risks;
  • identify the need for specific risk-minimisation measures, where appropriate;
  • ensure appropriate labelling is in place for users and healthcare professionals

The ERA considers solely the use of the medicine and the physico-chemical, ecotoxicological, and fate properties of its active substance. Risks to the environment from contamination caused by its manufacturing process, transport and storage fall outside the scope of the ERA.

    The outcome of the ERA is summarised in the assessment report of the Committee for Medicinal Products for Veterinary Use (CVMP) and is available in the medicine's European Public Assessment Report (EPAR).

    The ERA is tier-based and comprises two phases.

    Phase I: environmental impact assessment

    The phase I assessment determines the environmental exposure of the medicine and the need for an ecotoxicological assessment. It considers the medicine's active substance and excipients, its method of administration, target species and proposed pattern of use. It is mandatory for all veterinary medicines.

    Examples of veterinary medicines whose ERA ends in phase I are those with a predicted environmental concentration in soil (PECsoil) below the threshold value of 100 µg/kg, and medicines used to treat individual animals and pets. 

    Certain medicines whose phase I ERA concludes that their environmental exposure is negligible may still require a phase II assessment because of underlying concerns related to their intrinsic properties and their potential impact on the environment. These medicines undergo a tailored risk assessment to further investigate the suspected hazards they pose to individual environmental compartments.

    For more information on the phase I ERA, see:

    Phase II: ecotoxicological assessment

    Medicines whose phase I assessment concludes that their environmental exposure is not negligible (e.g. PECsoil value higher than 100 µg/kg) have to undergo an ecotoxicological assessment. This generally applies to veterinary medicines used for aquaculture, intensively reared terrestrial animals or pasture animals. 

    The ecotoxicological assessment is tier-based and is structured around the risk quotient (RQ), which provides an indication of the likelihood of adverse effects on the environment. The RQ is the ratio between the predicted environmental concentration (PEC) of the medicine and its highest concentration in any environment below which no adverse effects are expected (predicted no-effect concentration, or PNEC). 

    • Tier A investigations make use of data to calculate predicted no effect concentrations (PNECs) in different environmental compartments, usually soil and surface water. If PECs for all environmental compartments are below the corresponding PNECs, the ERA can be concluded.
    • Tier B is required to generate further data in those environmental compartments where the PEC is above the PNEC. In addition to worst-case assumptions, it considers more realistic exposure estimates to refine the PECs.
    • Tier C outlines field studies based on more realistic scenarios for applicants to conduct when the tier B assessment concludes that use of the product poses a risk to an environmental compartment.

    If the ERA determines that the use of the medicine will create an unacceptable risk for the environment, the applicant should propose mitigation measures to reduce the risk to an acceptable level.

    For more information on the phase II ERA, see:


    Guidance is available to help applicants calculate the environmental impact of their medicines.

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