Genotoxic activity of glyphosate and co-formulants in glyphosate-based herbicides assessed by the micronucleus test in human mononuclear white blood cells.

Glyphosate-based herbicides (GBHs) are widely used and contribute to soil, water, and air contamination. Despite differing assessments of its carcinogenic potential, glyphosate toxicity may be enhanced by the co-formulants (adjuvants) used to improve its effectiveness. In this study, we investigated the genotoxic effects of glyphosate, alkyl dimethyl betaine (adjuvant A), and polyethoxylated tallow amine (adjuvant B) on human peripheral white blood cells using a cytokinesis block micronucleus (CBMN) assay. The experiments tested Glyphosate (0.1, 1, 10, and 100 μM) and adjuvants (at concentrations matching their levels in respective GBHs) in whole blood samples. The samples were exposed for 4 and 20 h with and without S9 metabolic treatment. The results showed that glyphosate and adjuvant A caused a statistically significant increase in the frequency of binucleated cells with micronuclei (BNMN%) only at 100 μM after 4-hour exposure without S9 treatment. Adjuvant B, however, induced a statistically significant increase in BNMN% starting at 1 μM after 4-hour exposure without S9 treatment. No significant effects were observed after 4 h of exposure with S9 or 20 h of exposure, with or without S9. The proliferation index (PI) showed no significant changes. This study concluded that the co-formulants in GBHs can induce genotoxic effects at low concentrations and short exposure times. This indicated that some surfactants in GBHs may be more toxic than glyphosate.