Hitting two targets with one shot on pesticide genotoxicity assessment – Identifying risk while unveiling ex vivo approach as a throughput tool in gill-breathing animals

Pesticides in the environment often compromise the ecosystem, thus requiring reliable approaches to assess their effects. Commonly used approaches, such as in vivo, come with several disadvantages, namely in the light of the 3 R's policy. Seeking for accurate and ethical approaches, this study intended to validate the ex vivo technique as an alternative, and to assess the genotoxicity of chemically-based pesticides and a biopesticide. The ex vivo approach was applied to gill cells of Procambarus clarkii for 2, 4 and 8 h. Cell viability and DNA integrity were evaluated to determine the applicability of this approach. Crayfish gill cells only showed to be suitable for exposures of 2 h. Accordingly, genotoxicity was evaluated in gill cells exposed, for 2 h, to environmentally relevant concentrations of the chemically-based pesticides dimethoate (20 µg L^-1), imazalil (160 µg L^-1) and penoxsulam (23 µg L^-1), as well as to the bioinsecticide Turex® (25, 50, 100, 200 and 400 µg L^-1). Every chemically-based pesticide demonstrated to be genotoxic, despite not inducing oxidative DNA damage. On the other hand, Turex® showed no genotoxic effects. Overall, the ex vivo approach demonstrated to be possible and practical to implement, improving the number of outcomes with a lower number of organisms. The findings from the screening test suggest that biological pesticides may pose a lower risk to non-target organisms compared to chemically-based pesticides.