What pesticide monitoring misses

The most egregious example is chlorpyrifos, which the EPA phased out for home use in 2000, citing health and environmental concerns. As evidence of chlorpyrifos’ growing list of diverse health effects mounted in scientific journals, the agency proposed prohibiting all uses of the chemical in 2015 under the Obama administration. But two years later Trump’s EPA rescinded that rule, calling chlorpyrifos “crucial to U.S. agriculture,” and citing a return to “sound science in decision-making.”

Regulators also fail to account for risks associated with the scores of pesticides that don’t stay where they’re sprayed, creating a toxic environment for farmworkers and their families. It’s clear that workers have higher exposure, Trasande says, “and kids of workers can be exquisitely vulnerable.”

Unequal exposures

Pesticide residues can follow workers home from the fields on clothing and shoes, then collect in the dust on floors where babies and toddlers play. Several studies show that children of farmworkers routinely endure higher pesticide exposures than consumers and that mothers living close to fields treated with pesticides, including those on the dirty-dozen list, are more likely to have premature babies and children with autism, impaired cognitive function and other neurodevelopmental disorders.

Several pesticides have been linked to early puberty, impaired fertility and increased breast cancer risk, suggesting that young girls—whose brains and breasts undergo rapid development during puberty—may be particularly vulnerable to pesticide exposures. Researchers at the University of California, Berkeley, recently asked teenage girls living in the intensively farmed Salinas Valley to wear silicone wristbands—which soak up environmental chemicals like a sponge—to gauge their pesticide exposures. Dacthal and chlorpyrifos were among the most frequently detected pesticides for these Latina girls, and concentrations of dacthal and permethrin were three times higher for those who lived close to fields.

California, the nation’s most productive agricultural region, used close to 210 million pounds of pesticides in 2016, the most recent statistics available, including many classified as probable or possible carcinogens, endocrine disruptors (affecting the hormonal system) and reproductive or developmental toxicants. Farmers applied more than 380,000 pounds of dacthal on kale, broccoli, cauliflower and other crops in 2015 and 2016. The highest levels recorded in 2016 were in Lamont, a Central Valley town where the vast majority of residents are Hispanic and 35 percent of people live below the poverty line.

California growers applied 11.3 million pounds of pesticides to produce nearly 3 billion pounds of strawberries worth over $1.8 billion in 2016. For decades, the EPA gave strawberry growers an exemption to use methyl bromide, a fumigant banned by international treaty to protect the ozone layer that has also been tied to birth defects.

Growers lost that exemption in 2017, and had already turned to other fumigants—with similar toxic properties. But before they did, farmers routinely applied thousands of pounds of methyl bromide near predominantly Latino schools in violation of the federal civil rights laws. They applied more than 14,500 pounds of methyl bromide—in just 2015 and 2016 alone—within a mile of Oxnard’s Rio Mesa High School, where most students are Hispanic and which California health officials flagged as the school with the most toxic pesticides sprayed nearby in a 2014 report. During the same time, growers also doused fields near Rio Mesa with more than 142,000 pounds of chloropicrin, a choking agent once used in warfare and riot control, and 1,3-Dichloropropene (1,3-D), classified as a probable human carcinogen.

State regulators calculate risk based on averages of exposures to single pesticides over several months, even though growers can spray more than 100,000 pounds of fumigants like 1,3-D and chloropicrin in a single week. As a result, a 2016 study from the UCLA Sustainable Technology & Policy Program reported, “exposure to multiple pesticides occurs at a number of locations in the area, including sensitive sites like schools and daycares.” In addition, the study noted, human health risks from simultaneous exposures to drift-prone toxic chemicals like 1,3-D, chloropicrin and metam sodium (a methyl bromide replacement) “may be significantly greater than the added risks of the individual components.”

Last year California’s Department of Pesticide Regulation measured the highest levels of 1,3-D the agency ever recorded at a high school in Shafter, a small Central Valley town, where 83 percent of the population is Hispanic and 25 percent live below the poverty line. The levels far exceeded those the state deemed “unacceptably high” when it issued a temporary ban in 1990. The DPR relaxed its 1,3-D cancer risk standard in 2015, after the previous risk level was exceeded multiple times, says Anne Katten, director of the pesticide and worker safety project at the California Rural Legal Assistance Foundation.

Following the 1,3-D spike last year, Katten and members of other advocacy groups met with state officials to discuss the risks to the communities. In a follow-up letter, the group pointed out that the agency’s estimates of air concentrations far exceeded its own safety standards for both acute and chronic risks. “We urge DPR to immediately suspend all uses of 1,3-D,” they wrote in an email, citing risks to nearby homes and elementary schools.

State regulators declined, noting that the monitoring data did not justify action to curb 1,3-D use. They did not acknowledge that residents and workers could be exposed to other pesticides, along with 1,3-D, that might increase their risk. “The reality is that we have a regulatory framework that just assumes that these chemicals are fine and we don’t need to regulate them in agriculture,” Trasande says. “Even when the science tells us to do it.”