John Wiley & Sons, Ltd.

Re‐calibration of the earthworm tier 1 risk assessment of plant protection products

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In the first step of the earthworm risk assessment for plant protection products the risk is assessed by comparing the no‐observed effect levels (NOEL) from the laboratory reproduction tests with the predicted exposure of the plant protection product in soil while applying a trigger value (assessment factor; AF) to cover uncertainties. If this indicates a potential risk, field studies are conducted. However, the predicted environmental concentration in soil which can be calculated e.g. for different soil layers (ranging from 0‐1 cm to 0‐20 cm) and the AF determine the conservatism which is applied in this first step. In this review paper the tier 1 earthworm risk assessment for plant protection products is calibrated by comparing the NOEL in earthworm reproduction tests with effect levels on earthworm populations under realistic field conditions. A dataset of 54 pairs of studies conducted in the laboratory and in the field with the same plant protection product was compiled, allowing a direct comparison of relevant endpoints. The results indicate that a tier 1 AF of 5 combined with a regulatory relevant soil layer of 0‐5 cm provides a conservative tier 1 risk assessment. A risk was identified by the tier 1 risk assessment in the majority of the cases at application rates which were of low risk for natural earthworm populations under field conditions. Increasing the conservatism in the tier 1 risk assessment by reducing the depth of the regulatory relevant soil layer or by increasing the tier 1 AF would increase the number of false positives and trigger a large number of additional field studies. This would however not increase the margin of safety for earthworm populations. The analysis revealed that the risk assessment is conservative if an AF of 5 and a regulatory relevant soil layer of 0‐5 cm is used. This article is protected by copyright. All rights reserved

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