The United States Environmental Protection Agency (EPA) has immediately banned DCPA, known as Dacthal, a widely used herbicide in California. After mounting evidence of the chemical’s harmful effects on human health, the decision marks the first time in nearly 40 years that the EPA has exercised its emergency suspension powers.
DCPA has been used in the U.S. for almost 70 years, primarily on crops such as broccoli, onions, Brussels sprouts, and cabbage, as well as on golf courses and other grassy fields. However, the chemical has now been deemed too dangerous to remain on the market. The EPA’s emergency order, announced on Tuesday, was driven by findings that DCPA poses significant risks to pregnant women and their unborn children.
The herbicide has been linked to altering fetal thyroid hormone levels, which can lead to irreversible developmental issues such as low birth weight, impaired brain development, decreased IQ, and impaired motor skills. “It’s EPA’s job to protect people from exposure to dangerous chemicals. In this case, pregnant women who may never even know they were exposed could give birth to babies that experience irreversible lifelong health problems,” said Michal Freedhoff, Assistant Administrator for the Office of Chemical Safety and Pollution Prevention, in a statement.
Environmental advocates have welcomed the ban, though many argue it is long overdue. DCPA has been classified as a “possible human carcinogen” by the EPA since the 1990s and the European Union banned its use 15 years ago. Alexis Temkin, Senior Toxicologist at the Environmental Working Group, described the EPA’s decision as “welcome news, but it’s long overdue.”
According to state data, California has been the largest user of DCPA, accounting for nearly 200,000 pounds of the herbicide in 2021 and 2022. The heaviest use was recorded in Monterey County, where researchers from the University of California, Berkeley, found that over half of the nearly 100 Latina girls they studied, aged 14 to 16 and living in farmworker communities in the Salinas Valley, had been exposed to the chemical.
The herbicide has also been detected in groundwater in several California counties, including the Salinas Valley and Santa Barbara County. The California Department of Pesticide Regulation detected DCPA breakdown products in groundwater at concentrations up to 159 parts per billion in wells near Guadalupe, Santa Barbara County, and 101 parts per billion in a well near Greenfield in the Salinas Valley.
Although these levels are below the health-protective drinking water threshold set by the state, recent studies have highlighted the potential risks to fetal development even at low exposure levels.
The California Department of Pesticide Regulation acknowledged the EPA’s emergency order but lacked sufficient information to take independent action. Leia Bailey, the department’s deputy director of communications and outreach, explained, “The department would have had to conduct the same risk assessment, mitigation development, and regulatory steps U.S. EPA had already initiated and has now completed, which would have taken months to years for DPR to complete.”
AMVAC Chemical Corp., the Newport Beach-based manufacturer of DCPA, has stated that it is complying with the EPA’s order and had already voluntarily withdrawn the chemical from the market in May. “We have worked with [the EPA], and we will continue to work with them. We want to make sure that our customers don’t use the products… It’s not like we’re fighting this,” said Anthony Young, the company’s director of investor relations.
The EPA’s decision followed a long-running review of DCPA’s effects, including studies on pregnant rats that showed thyroid hormone changes, which could permanently affect human brain development. The agency has been pressuring AMVAC to submit data on the impact of chemicals on thyroid function in fetuses and children since 2013. Still, the company’s delays forced the EPA to take action.
This emergency order is critical in protecting public health, particularly for farmworkers and communities living near treated fields, who face the most significant risk of exposure. The EPA had already issued warnings to farmworkers earlier this year, and Tuesday’s ban underscores the agency’s commitment to addressing the severe and irreversible health risks posed by DCPA.
