Nearly a quarter of the rivers and streams in the continental United States carry the herbicide atrazine at concentrations the Environmental Protection Agency itself considers high enough to harm aquatic life, according to an analysis by the Center for Biological Diversity reported on 17 October. The study, led by the group's environmental health science director Nathan Donley, estimates that almost a million miles of waterways are affected and that about one in five surface-water drinking intakes in the country draws from them.
Atrazine is the second most widely used herbicide in the US after glyphosate, with about 70 million pounds applied each year, mainly on corn, sorghum and sugarcane to control broadleaf and grassy weeds. The analysis compared river and stream monitoring data with the EPA's own aquatic life benchmarks, the thresholds the agency uses to judge when pesticide levels in water pose an ecological risk.
The group also assessed the EPA's atrazine mitigation plan, finalised in December 2024, which set watershed-level concentration limits. By its analysis, the plan would bring only about 1% of the most heavily contaminated waterways down to safer levels. On 14 October the Center and allied groups sued the EPA, alleging that it has failed to protect waterways and drinking water from the chemical; a separate suit over the EPA's 2020 reapproval of atrazine is on hold while the agency redoes its risk analysis.
California's Office of Environmental Health Hazard Assessment said in early October that it plans to list atrazine as a known carcinogen under the state's Proposition 65 programme. The Center's report links atrazine exposure to lymphomas, breast cancer, reduced fertility and birth defects; those associations come from the advocacy group's own research summary, not from a new EPA risk finding, and the EPA's current registration decision does not classify atrazine that way.
Atrazine is banned in 63 countries, including every EU member state. Syngenta, the main manufacturer, says the product is safe when used according to the label, and the agrochemical industry argues that its value for weed control, reduced tillage and lower costs outweighs the risks found in advocacy-led water studies. The EPA had not publicly responded to the lawsuit or the findings.
Tighter US rules, whether through new EPA requirements, state carcinogen listings or court rulings, could change herbicide costs and weed-control programmes for corn, sorghum and sugarcane growers in North and South America, and would narrow the gap between US and EU pesticide standards.
Photo: Wikimedia Commons (public domain)
Source: Global Agriculture
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