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

Background: 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 safety assessment of pesticides. Methods: In the present study, an in vitro micronucleus test on intestinal Caco-2 human cells was performed according to OECD TG 487. Ten pesticides were tested (dose range 0-100 mg L^-1) either individually or as mixtures. Objectives: Assessing the genotoxicity of 10 commonly used pesticides and their mixtures. Findings: Significant dose-related increases in micronuclei were observed following exposure to lambda-cyhalothrin, tebuconazole, glyphosate, deltamethrin, fluopyram, and the synergist piperonyl butoxide. Significant increases in 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 the confounding effect 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 three prioritized pesticides (acetamiprid, glyphosate, tebuconazole) showed genotoxic effects even at the lowest dose. A combination of eight prioritized pesticides showed genotoxicity at the highest dose. No synergistic interactions in micronuclei formation were evident in either the mixture of three or eight prioritized pesticides. Conclusions: This study provides important information on the genotoxicity of different widely used pesticides and confirms the validity of a component-based approach in the genotoxicity assessment of pesticide mixtures. This study was performed as part of the EU SPRINT (Sustainable Plant Protection Transition: A Global Health Approach) project.