Evaluation of the immunotoxicity of atrazine and its chloro-metabolites: relevance for human cancer

This review was undertaken because it is known that high doses of atrazine activate the HPA axis, leading to increased corticosterone secretion, which could result in immunosuppression. The mammalian immunotoxicity of atrazine was evaluated based on <i>in vitro</i> and <i>in vivo</i> studies and the association between chlorotriazine use and the risk of cancer in humans based on epidemiological studies. <i>In vitro</i> studies reported that μM concentrations of atrazine may adversely affect cytokine production, lymphocytes, and dendritic cell function. However, there were no consistent patterns of effects of the chlorotriazines on the developing or mature immune system in sub-chronic, chronic, and lifetime animal studies. In a detailed immunotoxicity study on atrazine in rats, there were no effects of atrazine treatment on T-cell-dependent, IgM antibody production or natural killer cell activity. Based on the compendium of toxicology data reviewed, it was concluded that atrazine is unlikely to be immunotoxic at any dose to which humans might realistically be exposed. This conclusion was supported by epidemiological studies indicating that there was no consistent association between occupational exposure to atrazine and cancers of the immune system.