Food-related exposure to systemic pesticides and pesticides from transgenic plants: evaluation of aquatic test strategies

The aquatic Environmental Risk Assessment (ERA) for pesticides relies on standardized experimental protocols focusing on exposure via the water phase or the sediment. Systemic pesticides (e.g., neonicotinoids) or pesticides produced in transgenic plants (e.g., Bt proteins) can be introduced into aquatic ecosystems as part of plant residues. Consequently, they may be taken up by organisms as part of their diet. Here, we analyzed (i) whether standardized aquatic ecotoxicological test guidelines consider an exposure route via food and (ii) whether these tests can be easily modified to take this exposure route into account. From the 156 existing test guidelines, only those for fish and amphibians partly consider a potential route of uptake via food. From the remaining invertebrate guidelines, those focussing on chronic endpoints may be most suitable to cover this exposure path. We suggest assessing the food-related effects of systemic pesticides in a dose-dependent manner using standardized guidelines or methods developed from peer-reviewed literature. For transgenic plants, spiking uncontaminated leaf material with increasing concentrations of the test substances would allow to test for dose responses. After adaption to oral uptake, standard test guidelines currently available for the ERA appear, in principle, suitable for testing effects of systemic pesticides and transgenic plants.