Atrazine is one of the most common herbicides used in the United States, with over 70 million pounds applied to crops each year. Used mostly in large scale agriculture of crops such as corn, sugarcane, and pineapples, atrazine is the most widely detected herbicide in drinking water. Figures vary, but a conservative estimate puts measurable levels of atrazine in the drinking water of nearly 30 million Americans in 28 states. With so many people exposed to this compound, it is worth examining any potential effects it may have on people.

Atrazine seems to have three ways of harming human health. Firstly, research suggests it alters the levels of key hormones animals. In male frogs, for example, atrazine has been observed to trigger the development of female sex characteristics. In a more recent study, abnormalities in the male reproductive organs of marsupials exposed to atrazine have been documented. Secondly, atrazine seems to have detrimental reproductive effects. There are significant associations between exposure to the herbicide and effects such as increased risk of miscarriage, reduced fertility, low birth weight, and increased chance of birth defects. Finally, there is evidence that atrazine could have carcinogenic effects. Animal studies have found a strong connection between atrazine and breast cancer. More research is required to see if this connection holds in exposed human populations.

Atrazine levels in drinking water are capped at 3 micrograms per liter (µg/L) by the EPA. This Maximum Contaminant Level (MCL) as it is termed, however, is not based on health protective data, but on feasibility considerations for public water treatment systems. The state of California has developed entirely health-based protective values that are much smaller – 0.15 µg/L. This value should be the benchmark for drinking water systems, especially those in the Midwest where seasonal spikes of atrazine of more than 6 times the MCL have been recorded.