THE RECORD: Atrazine, Groundwater Testing, and the Limits of the Public Record

When you become immersed in the world of modern chemical contaminants, doing enough digging and enough researching often leads to mounds of information amid the public record. Information that may astonish you, leave you in shock, or surprise you in the worst way.

Atrazine is one of those compounds. But, the reports and documentation only stir so much, the real shock comes from what is left out and possibly dismissed.

Atrazine is a chlorinated herbicide used to prevent broadleaf weeds in crops such as corn, soybean, and sugarcane, as well as in turf landscaping including golf courses and residential lawns. It can infiltrate the human body through drinking water, ingestion, and dermal contact, and has been recognized as an environmental endocrine disruptor with documented adverse effects on the reproductive system, nervous system, adrenal glands, and thyroid gland.

In November 2025, the World Health Organization’s International Agency for Research on Cancer classified atrazine as probably carcinogenic to humans. The EPA responded by dismissing the classification, with an EPA spokesperson stating that IARC has a long history of being severely misguided in its findings. (IARC, 2025)

The timeline:

Italy began limiting atrazine use in 1986 due to groundwater contamination in northern Italy, with later sources describing a nationwide ban in the early 1990s. Germany banned it the same year, in March 1991. Germany simultaneously established 60 groundwater observation wells to directly monitor what remained in the ground beneath agricultural land. (Ghirardelli et al., 2021; Giupponi et al., 2001; Vonberg et al., 2014)  

In 1994, one crop field compliance check was conducted in Germany. Of 471 maize fields tested, 6.2% showed evidence of atrazine application despite the prohibition. However, there is no follow-up crop field testing in the published record after that single study. (Tappe et al., 2002)

Also in the 1990s, USDA analyses concluded that banning atrazine would result in only a modest reduction in corn yields, with one widely cited estimate placing the decline at 1.19 percent, and the United States chose against a ban. (Ackerman, 2007)

In 2003, while atrazine was under formal review by the U.S. EPA, Syngenta participated in approximately 50 closed-door meetings with EPA regulators. The meetings were not publicly announced, and documents about them were only made public after the Natural Resources Defense Council filed suit. (Muir, 2010)

Germany’s 60 groundwater wells continued sampling through that same period. From 1991 through 2011, groundwater concentrations remained close to the threshold limit, showing only a slow decline and a stable spatial pattern. Soil residue analysis showed atrazine persisting for more than two decades after the last known application, with continued release from soil into groundwater sustaining elevated concentrations long after use stopped. (Vonberg et al., 2014)

Between 2013 and 2017, an annual average of about 72 million pounds of atrazine were applied in U.S. agriculture, and the EPA has stated that atrazine is used on about 75 million acres of agricultural cropland every year. So, while other nations banned this compound decades ago, the United States has continued to apply upwards of 70 million pounds of atrazine annually. (U.S. EPA, 2020)

In 2020, the EPA discontinued its Atrazine Monitoring Program, citing model-estimated concentrations as sufficient justification to end actual sampling requirements. (U.S. EPA, 2025)

Yes, they decided estimation was good enough.

Monitoring Systems

Germany directly sampled raw groundwater at fixed physical wells for twenty years after banning the compound. The United States, while continuing to apply it, monitored treated community drinking water supplies rather than raw agricultural groundwater. Because atrazine levels tend to be higher in surface water than in groundwater, surface water was the EPA’s focus for its monitoring program, which covered community water systems. The monitoring data covers public water systems only, while private well water was not included in those tests. (Vonberg et al., 2014; U.S. EPA, 2025)

The disconnect lies in the lack of data, lack of testing, and/or lack of public information. Instead of monitoring and testing ground water where atrazine is most heavily present, as well as further from application sites, the United States uses predictive models built in part using proprietary data from a private market research firm. (U.S. EPA, 2025)

The Standards

The EU groundwater quality standard for atrazine is 0.1 micrograms per liter. The U.S. drinking water standard is 3.0 micrograms per liter, thirty times higher than the threshold that led Europe to ban the compound. (Vonberg et al., 2014)

Atrazine is but one compound, and yet it raises multiple questions about quality, assurance, and safety.

Questions about what is measured, access to data, and whether agencies designed to protect the environment and living things are functioning in that capacity.

There is so much more to Atrazine, its uses globally, and its impact on the environment and human bodies alike.

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Sources

IARC. 2025. “IARC Monographs evaluation of the carcinogenicity of atrazine, alachlor and vinclozolin.”

Ghirardelli, A., et al. 2021. “Thirty-year monitoring of s-triazine herbicide contamination in the aquifer north of Vicenza (north-east Italy).” Science of the Total Environment.

Vonberg, D., et al. 2014. “20 years of long-term atrazine monitoring in a shallow aquifer in western Germany.” Water Research.

Tappe, W., et al. 2002. “Diffuse atrazine pollution in German aquifers.” Biodegradation.

Ackerman, F. 2007. “The Economics of Atrazine.” International Journal of Occupational and Environmental Health.

Muir, C. 2010. The Great Atrazine Cover-Up: How the EPA Is Poisoning America’s Drinking Water.

U.S. EPA. 2020. Atrazine: Interim Registration Review Decision Case 0062.

U.S. EPA. 2025. “Atrazine Monitoring Program Data and Results.”