Political Officials Pressured EPA Scientists to Undermine Scientific Studies on a Hazardous Pesticide, Atrazine – Again

Published Sep 22, 2022

What Happened: Political officials directed scientists at the Environmental Protection Agency (EPA) to exclude key studies when looking at a popular pesticide, atrazine, in a way that downplayed its harmful environmental effects. The scientists refused to alter the science but felt enough political pressure that, in an official memo by the EPA, the scientists gave more weight to industry benefits, setting a regulatory level for atrazine that was over four times higher than the level scientists said was harmful.

Why It Matters: By trying to exclude scientific studies when evaluating potentially hazardous pesticides, the EPA is failing to abide by its mission statement and is favoring political motivations over science-based evidence. Science is critical to inform policies that protect the environment from chemical exposures that are harmful. The best available science suggests that atrazine contamination of waterways can cause substantial harm to aquatic habitats.

Political officials under the Trump administration tried to suppress a scientific review of the hazardous herbicide, atrazine, by pressuring Environmental Protection Agency (EPA) scientists to exclude key ecological studies and downplay its role as a groundwater contaminant, influencing science policy decisions in a way that would be favorable to industry. The scientists did not exclude the studies but felt enough political pressure to give more weight to industry benefits in an official memo, resulting in a less protective regulatory level for atrazine.

Atrazine is a popular herbicide that is used to selectively control annual grasses and broadleaf weeds. Due to its dangers to human and environmental health, it is banned or being phased out in dozens of other countries. In 2016, EPA scientists conducted an ecological risk assessment and determined that when atrazine exceeded 3.4 micrograms per liter in waterways, it had a high probability of negatively impacting aquatic plants and life. The assessment concluded that there was potential chronic risk to fish, amphibians, and other aquatic species. EPA scientists found that “chronic risks [were] exceeded by as much as 22, 198, and 62 times for birds, mammals, and fish, respectively.” In 2019, an official memo by the EPA established the regulatory level of atrazine at 15 micrograms per liter in water, a less restrictive regulatory level that is over four times higher than the levels that EPA scientists previously identified as harmful to aquatic species.

In July 2022, three agency staff members reported that during the Trump administration, EPA officials ignored scientific integrity guidelines and interfered with the registration review process for atrazine. A former pesticides program career official stated that the atrazine registration decision followed a similar decision where the EPA downplayed the risks of another hazardous pesticide, dicamba. Similar instances of political opinion unduly influencing pesticide regulation have occurred since at least 2004, including cases of interference on atrazine regulation in 2013 and 2017. In this recent case, while EPA scientists refused to alter the science around atrazine, pressure from political appointees still influenced the outcomes of the atrazine regulatory level.

The decision-making process for pesticide regulation should be guided by the best available evidence. The EPA is required by law to follow routine procedures to evaluate pesticide assessments during the registration review process, a process which that has been rigorously developed to reflect the best available science. The EPA has a duty to conduct high-quality science that is guided by scientific integrity. By failing to do so, the agency’s actions likely allowed the continued contamination of thousands of waterways across the United States, harming not only aquatic life but the humans and wildlife that depend on healthy drinking and surface water for survival.