Fate, uptake, and distribution of nanoencapsulated pesticides in soil–earthworm systems and implications for environmental risk assessment

Mohd Anuar Mohd Firdaus, Annika Agatz, Mark E. Hodson, Omar S.A. Al‐Khazrajy, Alistair B.A. Boxall

Nanopesticides are novel plant protection products offering numerous benefits. As nanoparticles behave differently from dissolved chemicals, environmental risks of these materials could differ from conventional pesticides. Here we used soil-earthworm systems to compare the fate and uptake of analytical grade bifenthrin to that of bifenthrin in traditional and nano-encapsulated formulations. Apparent sorption coefficients for bifenthrin in the nano-treatments were up to 3.8 times lower than in the non-nano treatments whereas dissipation half-lives of the nano-treatments were up to two time longer. Earthworms in the nano-treatments accumulated around 50% more bifenthrin than those in the non-nano treatments. In the non-nano treatments, most of the accumulated material was found in the earthworm tissue while in the nano-treatments, the majority resided in the gut. Evaluation of toxicokinetic modelling approaches showed that models incorporating the release rate of bifenthrin from the nanocapsule and distribution within the earthworm provided the best estimations of uptake from the nanoformulations. Overall, our findings indicate that the risks of nanopesticides may be different from conventional formulations. The modelling presented here provides a starting point for assessing risks of these materials but needs to be further developed to better consider the behaviour of the nanoencapsulated pesticide within the gut system. This article is protected by copyright. All rights reserved.