YUMA – As night falls over the 121-square-mile stretch of land at the corner of California, Arizona, and Mexico – land almost twice the size of Washington, D.C. – crop planes and helicopters boot up.
Under the cover of darkness, pilots drop thousands of pounds of pesticides over fields in one of the nation’s most productive agricultural regions growing lettuce, wheat, melons, lemons, and dozens of other crops.
A few hours later, legions of farmworkers head to these same fields to plant, irrigate, pick, cut, bag, and run machinery.
The scale is massive: the region’s industry generated over $4.4 billion in the Arizona economy in 2022, according to a study by the Department of Agricultural & Resource Economics and the University of Arizona Cooperative Extension.
Farms in Yuma have shifted from mass-produced field crops, such as alfalfa and cotton, to high-value specialty crops, including lettuce, which sell at higher prices and require more labor. This makes vegetable farming employment in the Yuma area 58 times higher than the national average.
That means more money, more labor, more pesticides, and, according to a growing body of research, more adverse health effects among farmworkers.
Yuma County employs more than 80% of the state’s agricultural workforce. The county has more than 65,000 farmworkers, including about 16,000 migrant workers and roughly 50,000 seasonal workers.
Researchers and advocates have long raised concerns about the adverse short- and long-term effects of pesticides—these range from headache and nausea to cancer, Parkinson’s disease, diabetes, and stillbirths.
“In rural agricultural areas where people are working on farms, there are higher incidences of diabetes, obesity, pulmonary issues, endocrine disruption, cancer …” said Sara Grantham, the advocacy manager at Beyond Pesticides, a D.C.-based nonprofit that advocates for non-chemical alternatives in agriculture.
Multiple reports link these conditions to the environmental toxins to which farmworkers are exposed. Many of them also examine a potential link between pesticides and chronic health effects.
“We do believe any synthetic pesticides or fertilizers are going into our environment, they’re going into our bodies, and they’re poisoning us,” Grantham said. “This science isn’t new”.
The science is nearly 60 years old; however, the impact of these pesticides remains alarmingly current, as evidenced by comprehensive studies conducted over the past 20 years.
From 2013 to 2016, diabetes rates among Southwest farmworkers were almost twice the national average. Researchers and healthcare professionals noted the heightened risk among Latino communities and said pesticide exposure may compound that risk by interfering with hormone regulation.
“Some pesticides and herbicides that we’re using affect different hormone imbalances in the body. Many of the chemicals we use are endocrine disruptors,” said Dr. Luc Lanteigne, a physician in Yuma’s largest medical center, Onvida Health.
However, tracking the health effects of pesticide exposure in Yuma is difficult, in part because the region’s farm labor force is uniquely mobile.
According to a 2024 estimate of Yuma’s farmworker population, cross-border labor is a core part of the region’s agricultural workforce.
“We have people who come across every single day,” said Katherine Ellingson, an epidemiologist and co-author of the report.
In recent years, growers have increasingly relied on H-2A visas, which allow them to hire foreign nationals for temporary farm work when domestic labor is unavailable.
The number of H-2A workers has grown sixfold nationwide since the early 2000s, with more than 10,000 visas certified in Arizona in 2023.
The reliance on short-term, cross-border labor, often hired by contractors working with growers, makes it difficult to track health outcomes.
“Growers in Yuma might have 20 to 30 full-time employees that get health benefits and vacation days, and they’re really proud of taking care of them,” Ellington said. “But most of the actual labor, at least with certain crops like lettuce, melons … is done by the temporary workforce they don’t even have on payroll.”
Workers may return to Mexico or move on to other states, meaning effects of pesticide exposure – especially long-term – often go unreported.
The Environmental Protection Agency sets national standards to protect agricultural workers from pesticide exposure. Still, Grantham said these guidelines are inadequate as the EPA does not include independent scientific data when registering or re-registering pesticides and “only consults the industry-provided data.”
“They (the EPA) do not currently study any of the active ingredients that go into pesticide products sufficiently,” Grantham said. “They don’t look at cumulative effects. They don’t look at synergistic effects.”
Cronkite News reached out to the EPA for comment, but the agency did not make anyone available for an interview.
Some national voices argue that systemic factors deepen the challenges. “Farm workers are in one of the least empowered positions in our economy,” said Alexis Guild, the vice president of strategy and programs at Farmworker Justice, a national nonprofit that advocates for better working conditions and safety in agriculture. “If they speak up about unsafe conditions — whether that’s pesticides, heat, or breaks — they risk retaliation or losing their jobs. That imbalance makes enforcement incredibly difficult”.
This does not mean there’s no progress. Farmworker Justice is a part of the EPA’s Pesticide Program Dialog Committee, which worked to pass the 2022 Pesticide Registration Improvement Act (PRIA-5). This law, among other things, mandates pesticide labels to be in English and Spanish.
Advocates say that farmwork is essential and skilled, and protecting workers’ health is a matter of basic dignity.
“If you talk to farm workers, they’re extremely proud of the work that they do, and they are extremely proud of their contributions to their communities, to the economy, to the country,” Guild said. “I think that this narrative often gets lost.”
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