Evaluation of various glyphosate concentrations on DNA damage in human Raji cells and its impact on cytotoxicity

- Significant DNA damage and cellular death occurs when Raji cells are exposed to glyphosate concentrations at or above 10 mM.
- Glyphosate concentrations below 10 μM do not induce significant DNA damage and cells maintain full long term viability.
- Intermediate glyphosate concentrations induce initial damage, but undergo repair that leads to eventual viability.
- Discrepancies in regards to cytotoxicity may be due to inconsistent time points that show alternative damage.

Glyphosate is a highly used active compound in agriculturally based pesticides. The literature regarding the toxicity of glyphosate to human cells has been highly inconsistent. We studied the resulting DNA damage and cytotoxicity of various glyphosate concentrations on human cells to evaluate DNA damaging potential. Utilizing human Raji cells, DNA damage was quantified using the comet assay, while cytotoxicity was further analyzed using MTT viability assays. Several glyphosate concentrations were assessed, ranging from 15 mM to 0.1 μM. We found that glyphosate treatment is lethal to Raji cells at concentrations above 10 mM, yet has no cytotoxic effects at concentrations at or below 100 μM. Treatment concentrations of 1 mM and 5 mM induce statistically significant DNA damage to Raji cells following 30-60 min of treatment, however, cells show a slow recovery from initial damage and cell viability is unaffected after 2 h. At these same concentrations, cells treated with additional compound did not recover and maintained high levels of DNA damage. While the cytotoxicity of glyphosate appears to be minimal for physiologically relevant concentrations, the compound has a definitive cytotoxic nature in human cells at high concentrations. Our data also suggests a mammalian metabolic pathway for the degradation of glyphosate may be present.