Mechanisms of Neurotoxicity Associated with Exposure to the Herbicide Atrazine

Atrazine is an herbicide commonly used on crops to prevent broadleaf weeds. Atrazine is an endocrine-disrupting chemical mainly targeting the neuroendocrine system and associated axes, especially as a reproductive toxicant through attenuation of the luteinizing hormone (LH). Current regulatory levels for chronic exposure are based on no observed adverse effect levels (NOAELs) of these LH alterations in rodent studies. Atrazine has also been studied for its effects on the central nervous system and neurotransmission. The European Union (EU) recognized the health risks of atrazine exposure as a public health concern with no way to contain contamination of drinking water. As such, the EU banned atrazine use in 2003. The United States recently reapproved atrazine's use in the fall of 2020. Research has shown that there is a wide array of adverse health effects that are seen across multiple models, exposure times, and exposure periods leading to dysfunction in many different systems in the body with most pointing to a neuroendocrine target of toxicity. There is evidence of crosstalk between systems that can be affected by atrazine exposure, causing widespread dysfunction and leading to changes in behavior even with no direct link to the hypothalamus. The hypothetical mechanism of toxicity of atrazine endocrine disruption and neurotoxicity can therefore be described as a web of pathways that are influenced through changes occurring in each and their multiple feedback loops with further research needed to refine NOAELs for neurotoxic outcomes.