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.