Rodenticide screening 2016–2018 - Exposures in birds (raptors and gulls) and red foxes

This screening study aims at investigating whether anticoagulant rodenticides can be detected in non-target organisms, and if the levels are different compared with the results from a previous study. Foxes, birds of prey and gulls were included as non-target organisms. The levels detected in the present screening study were similar to those found earlier and support that rodenticides are transferred in the food web and may be the cause of secondary toxicity in non-target mammals and birds in Sweden.

Summary

Rodenticides are biocidal products that are used in order to control rats and mice. This screening study aims at investigating whether chemical substances belonging to the group anticoagulant rodenticides can be detected in Swedish non-target biota, and to investigate if the levels are different compared with the results from a previous study.

The levels of anticoagulant rodenticides detected in the present screening study are similar to those found in earlier studies in Sweden and elsewhere. The literature indicates that toxic effects can occur in birds at levels > 100 ng/g (liver) whereas the level > 200 ng/g has been proposed to be a threshold level in foxes. Some individuals of raptors (n =2) and several foxes (n = 7) exceed these levels in the present study. These data suggest that anticoagulant rodenticides that are transferred in the food web may cause secondary toxicity in non-target mammals and birds in Sweden. However, no pathology has been performed for the individuals of the present study that can confirm any concentration-effect relationship or reason for mortality.

Coworkers: Tomas Viktor, Jasmin Sandberg

Year: 2019

Report number: C440

Authors: Jenny Asaa, Jasmin Sandberg, Tomas Viktor, Johan Fång

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