Presence of insecticidal veterinary medicines in dandelions (Taraxacum officinalis) in public parks in the Netherlands

The aim of this study was to investigate the presence of insecticidal veterinary medicines in public parks in the Netherlands and to determine whether those substances might pose a threat to the local entomofauna. Fifteen parks were selected throughout the country, and volunteers took composite samples of dandelion plants. Samples were collected in 2021 and 2022. In total, nine insecticidal veterinary medicines were detected, including two isomers of permethrin and two metabolites of fipronil. As four out of the six parent compounds detected are currently mainly on the market for use on pets, it is plausible that these substances originate from dogs and cats visiting the parks. The other two compounds, i.e., phoxim and etofenprox, are likely to have originated from airborne deposition, as earlier studies have reported the presence of these substances in polyurethane air filters and in untreated vegetation. Toxicological literature indicates that the concentrations found for permethrin, imidacloprid, fipronil and its metabolites are likely to trigger negative effects in butterflies feeding on the dandelions.