Safety assessment of nanopesticides using the roundworm Caenorhabditis elegans

- Polymeric and lipid NPs without pesticides showed toxic effects to C. elegans.
- The observed effects were caused by the nanoparticles themselves.
- Development of nanoparticles needs improvements to reduce toxicity.

The extensive use of pesticides is causing environmental pollution, affecting animal organisms in different habitats and also leading human health at risk. In this study, we present as an alternative the use of nanoparticles loaded with pesticides and report their toxicological assessment to a soil organism, Caenorhabditis elegans. Three nanoparticle formulations were analyzed: solid lipid nanoparticles loaded or not with atrazine and simazine, SLN; polymeric nanoparticles, NC_PCL loaded with atrazine; and chitosan/tripolyphosphate, CS/TPP, loaded or not with paraquat. All formulations, loaded or not with pesticides, increased lethality in a dose- dependent manner with similar LC50. Both loaded and unloaded NC_PCL were the most toxic formulations to developmental rate, significantly reducing worms length, even at low concentrations. In contrast, both CS/TPP nanoparticles were the least toxic, not affecting reproduction and body length at higher concentrations, probably due to the biocompatibility of chitosan. The physico-chemical characterization of nanoparticles after incubation in saline solution (used in exposure of organisms) has shown that these colloidal systems are stable and remain with the same initial characteristics, even in the presence of saline environment. Notably, our results indicate that the observed effects were caused by the nanoparticles per se. These results suggest that the development of nanoparticles aiming agriculture applications needs more studies in order to optimize the composition and then reduce their toxicity to non-target organisms.