Multiple Pesticides and their Mixtures Tested for Genotoxicity in the Micronucleus Assays on Intestinal Caco-2 Cells

Widespread exposure to multiple pesticides might potentially represent a genotoxic risk to humans. However the effects of these mixtures are largely unknown. Genotoxicity is a key characteristic of carcinogens, and its assessment represents an important component of the overall safety assessment of pesticides. In the present study, in vitro micronucleus test on intestinal Caco-2 human cells was performed according to OECD TG 487 in order to ascertain the genotoxicity of ten commonly used pesticides (dose range 0-100 mg L-1), tested as individual pesticides or mixtures. Significant dose-related increases in micronuclei were observed for exposures to lambda-cyhalothrin, tebuconazole, glyphosate, deltamethrin, fluopyram and the synergist piperonyl butoxide. Significant increases of micronuclei were also observed at different doses for cypermethrin, acetamiprid and cyprodinil, however these increases were not dose-dependent. Imazalil genotoxicity could not be analyzed due to confounding of high cytotoxicity even at low doses. Results show that the co-formulant piperonyl butoxide was genotoxic to human cell lines at all tested doses. Moreover, glyphosate, acetamiprid and fluopyram showed genotoxic effects at concentrations of 0.01-1.0 mg L-1. Although previously reported to be not genotoxic cyprodinil and deltamethrin were observed to be genotoxic to Caco-2 cells. A combination of 3 prioritzided pesticides (acetamiprid, glyphosate, tebuconazole) showed genotoxic effects even at the lowest dose. A combination of 8 prioritized pesticides showed genotoxicity at the highest dose. No synergistic interactions in micronuclei formation were evident in either the mixture of 3 or 8 prioritized pesticides. This study provides important information on the genotoxicity of different widely used pesticides and confirms the validity of a component-based approach in genotoxicity assessment of pesticide mixtures. This study was performed as part of the EU SPRINT (Sustainable Plant Protection Transition: A Global Health Approach) project.