This story was produced by the Food & Environment Reporting Network, an independent nonprofit news organization.

When Dayane Zuñiga started running for Oxnard High School’s track team a few years ago, she often noticed an odd odor coming from the strawberry fields on her route. A farming community between the beach towns of Santa Barbara and Malibu, California, Oxnard is among the largest strawberry-growing regions in the nation. At first, Zuñiga didn’t pay much attention to the smell. Growing up near agriculture, she was used to odd odors.

Then one day during practice, Zuñiga saw men working in the fields with face masks and smelled the same odor. Suspecting they were applying chemicals, she wondered why no one had warned her team. She asked her principal if the administration ever got notices about pesticide use around the school, attended by more than 3,200 kids. He told her it did, in accordance with strict regulations, and that she had nothing to worry about.

So Zuñiga put pesticides out of her mind. When she smelled a pungent odor, she ran faster to reach a patch of fresh air. When her asthma acted up, she puffed on her mini-inhaler and kept running.

Now she wishes she had asked more questions.

Oxnard and surrounding Ventura County grow more than 630 million pounds of strawberries a year, enough to feed 78 million Americans. But that bounty exacts a heavy toll: strawberries rank among California’s most pesticide-intensive crops. The pesticides that growers depend on—a revolving roster of caustic and highly volatile chemicals called fumigants—are among the most toxic used in agriculture. They include sixty-six chemicals that have been identified by the state’s Office of Environmental Health Hazard Assessment as the most likely to drift through the air and cause harm. Studies in laboratory animals and humans have linked many of these chemicals—including the organophosphate chlorpyrifos and fumigants 1,3-Dichloropropene (1,3-D), metam sodium, methyl bromide and chloropicrin, all used in strawberry production—to one or several chronic health conditions, including birth defects, asthma, cancer and multiple neurodevelopmental abnormalities.

Dayane Zuñiga

Use of many of these sixty-six pesticides has fallen statewide since 2007. But a handful of communities saw a dramatic increase. By 2012, the most recent year for which data is available, more than 29 million pounds of these chemicals—more than half the total used in the state—were applied in just 5 percent of California’s 1,769 census ZIP codes, according to an independent investigation by this reporter. In two ZIP codes that Zuñiga knows well—areas that include the Oxnard High neighborhood where she trained and south Oxnard, where she lives—applications of these especially toxic pesticides, which were already among the highest in the state, rose between 61 percent and 84 percent from 2007 t0 2012, records at the California Department of Pesticide Regulation show. Both are among the ten ZIP codes with the most intensive use of these pesticides in California. And both have sizable Latino populations—around 70 percent—thanks, in part, to the large number of farm jobs in the area. The great majority of the people who work in the strawberry fields in Oxnard, which hosts the largest population of farmworkers in Ventura County, come from Mexico.

Last year, the California Department of Public Health’s Environmental Health Tracking Program released the first state study to systematically review pesticide use near schools. Health officials tracked pesticides applied in 2010, focusing on those most likely to harm children based on known health effects or regulatory status. Ventura County had more schools and more students—over 13,000—attending classes within a quarter-mile of areas most heavily treated with potentially harmful pesticides than any other county in the state. And Oxnard was home to over one-fourth of the schools next to fields with the highest pesticide use, data obtained from the health department show. But no school had higher use of these pesticides nearby than Rio Mesa High School, a fifteen-minute drive from Oxnard High, with nearly 29,000 pounds of pesticides applied within a quarter-mile of campus.

Agricultural interests and pesticide regulators argue that just because chemicals are used near schools, it doesn’t mean they will have harmful effects. And harm is difficult to prove, because the health consequences of chronic exposure to low levels of hazardous substances can take decades to show up, if they show up at all. But scores of studies have shown that living near areas of high pesticide use is a major route of exposure, which has led health experts and even the US Environmental Protection Agency to conclude that the risks of long-term health problems for these schoolchildren are real.

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If the concentrated use of pesticides near predominantly Latino communities seems unfair, some have argued that it’s also illegal. Parents of students at Rio Mesa High School first raised that question sixteen years ago, after the Environmental Working Group, a research and advocacy organization, reported in 1998 that thousands of pounds of the fumigant methyl bromide were routinely applied within close range of California schools. Methyl bromide, a potent neurotoxic agent that can cause involuntary twitching, neurodegeneration and even death, is applied to fields before planting to wipe out pests and soil diseases and for decades was strawberry growers’ preferred fumigant. In the EWG study, Rio Mesa, with 2,169 students at the time, ranked second statewide when it came to methyl bromide use within a mile and a half of a school. The top-ranked position was held by an elementary school in Oxnard.

Children who attended schools near the highest applications of methyl bromide, among the most widely used pesticides in California then, also faced the highest risk of exposure to all pesticides. And, as their families noted in a civil-rights complaint, more than 80 percent of these students were children of color, primarily Latino.

Since Title VI of the Civil Rights Act prohibits recipients of federal funding from discriminating on the basis of race, color or national origin, the findings opened the door to a legal strategy to protect the children’s health. The EPA regularly awards millions of dollars in grants to California’s Department of Pesticide Regulation. In order to accept federal funds, state pesticide regulators are required to comply with the Civil Rights Act. The EPA, in turn, is obligated to enforce the Civil Rights Act by ensuring compliance. Six parents, who withheld their last names in the action to shield themselves from potential backlash from agricultural interests, filed a complaint with the EPA in 1999, charging that state regulators violated federal discrimination laws.

In filing, the parents were taking an unusual step. Many were farmworkers who spent their days picking strawberries and other crops in California’s rich agricultural regions. By going to the EPA, they were not only taking on their employers, but they were doing so from highly vulnerable positions. Over half of Ventura County’s farmhands are undocumented. And many fear that they could risk deportation by targeting pesticides. Even those who immigrated legally still say they could lose their jobs if they speak out.

Yet the six parents who stepped forward, including one known as Maria G., a farmhand whose son attended Rio Mesa High, were optimistic that the state would take action and reduce pesticide use near their children’s schools. At the very least, they wanted the state to prohibit the use of the most dangerous pesticides near neighborhoods and schools.

Few studies have examined methyl bromide’s effects on children. But even in the 1990s, pesticide regulators knew that chronic exposure to the neurotoxic chemical could disrupt fetal development in laboratory animals. Recent evidence suggests that methyl bromide can cause birth defects in humans, too. In a 2013 Environmental Health Perspectives study, researchers at the University of California, Berkeley, reported that pregnant women who lived within three miles of “moderate” (2.2 to 32,386 pounds) to “high” (32,386 to 168,225 pounds) methyl bromide use during their second trimester were more likely to have babies that weighed less and had smaller heads and shorter bodies than mothers who didn’t live near methyl bromide applications.

When the parents filed their complaint, growers were far exceeding the moderate levels later described in the UC Berkeley study, applying anywhere from 67,000 pounds to 170,000 pounds of methyl bromide within a mile and a half of Rio Mesa High School each year. No studies of the potential consequences of these specific applications have been published, but researchers have long known that growing children are more susceptible to long-term harm from toxic agents than adults.

* * *

Once a civil-rights complaint is filed, the EPA is required to acknowledge the complaint within five days and then indicate whether it will investigate it within twenty days. Twenty-five days went by, and the parents heard nothing. Days turned to months, and still no word came from the EPA. The agency would later defend its failure to respond to the families by likening civil-rights complainants to “tipsters” whom it could choose to involve or not. The characterization did not sit well with the families’ attorney, Brent Newell of the Center on Race, Poverty and the Environment (CRPE). “What EPA doesn’t get,” he says, “is that these are people who are suffering from discrimination and trying to get a remedy, and EPA treats them as if they’re someone dropping a dime on a criminal.”

The families had expected that the EPA would at least keep them in the loop as it investigated their claim. Little did they know it would take more than a decade to get any resolution.

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The families’ complaint hinged on whether pesticide use in California was having a disproportionate impact on students of color by placing them at higher risk of exposure—a risk that couldn’t be immediately seen. With acute poisoning incidents, however, the risks posed by proximity to pesticides are harder to deny.

On the morning of November 8, 2000, a Ventura County citrus grower air-blasted the pesticide chlorpyrifos on his lemon orchard, a short drive from Rio Mesa High and a stone’s throw from Mound Elementary School, just as parents were dropping off their children. Unlike Rio Mesa, Mound is a magnet school where, in 2000, nearly 80 percent of the 575 students were white.

Children played outside as the pesticide drifted from the orchard across the narrow lane separating the grove from the school. Nearly forty people, mostly children, complained of dizziness, cramping, nausea, vomiting, asthma and “flu-like” symptoms—all signs of immediate poisoning. Chlorpyrifos, like methyl bromide, can cause respiratory paralysis and death at high doses, and the EPA had banned it for home use just six months earlier.

“Several of the kids had to go to the hospital, and the parents were furious,” says Hannah-Beth Jackson, who was serving in the State Assembly at the time. By February 2001, Jackson had drafted and introduced a bill to increase regulatory oversight of pesticide use near schools and other sensitive sites and to give county commissioners the authority to curtail pesticide use within a quarter-mile of schools.

A few months after Jackson introduced her bill, Ventura County prosecutors sued the ranch owner and his foreman for allowing the pesticide to drift onto the school. Within a year, the rancher agreed to pay a $25,000 fine and avoid spraying within 200 feet of the street that borders Mound until 6 pm on school days. And in September 2002, less than two years after the incident, Jackson’s bill was signed into law.

All exposures aren’t so dramatic, typically occurring as chronic, low-level doses. And their impact, when studied, is more often measured over years or decades, showing up as developmental delays, Parkinson’s and other neurodegenerative diseases or cancers, including childhood leukemia. These were the kinds of chronic exposures the families feared were occurring at Rio Mesa and other largely Latino schools in Oxnard that state pesticide regulators had deemed safe.

Toxicological and animal studies, as well as emerging evidence from human studies, appear to undermine such assurances, however. Several types of pesticides, including carbamates, pyrethroids, organochlorines and organophosphates like chlorpyrifos, which was used near Mound Elementary, work by disrupting enzymes and chemicals in insects’ nervous systems. They kill by interfering with nerve cell signals to muscles, and between nerve cells in the brain, causing convulsions, paralysis or death. At high enough levels, they can cause similar effects in humans. Men exposed to even low levels of these chemicals over several years on the job as pesticide applicators reported diverse neurological problems, including difficulty seeing, concentrating and walking, according to the National Cancer Institute’s ongoing Agricultural Health Study.

Fumigants like methyl bromide, applied near Oxnard and Rio Mesa high schools, can also poison the nervous system, though studies of protracted exposures to fumigants in humans are limited.

Brenda Eskenazi, an epidemiologist at UC Berkeley, has investigated the effects of chronic pesticide exposure on families in the Salinas Valley since 1999 through the Center for the Health Assessment of Mothers and Children of Salinas study. Working with the CHAMACOS mothers, many of whom were born in Mexico, Eskenazi’s group has found associations between prenatal exposure to organophosphates and impaired motor control and cognition, including lower IQs.

Epidemiologist Irva Hertz-Picciotto, at the University of California, Davis, has also found strong associations between several classes of pesticides and impaired cognitive development following exposure in the womb, a period of rapid growth when cells form the structures and connections that underlie brain function.

In addition, researchers have found that proximity—that is, how close you happen to be to pesticide applications—does matter, despite official assurances to the contrary. In a study published last year in Environmental Health Perspectives, Hertz-Picciotto found that women living within nine-tenths of a mile of fields treated with organophosphates, including chlorpyrifos, were 60 percent more likely to have children with autism spectrum disorders than women who did not live near fields. Her team found a 14 percent higher rate of autism for each 100-pound increase in chlorpyrifos applied over the course of pregnancy.

And as early as 2001, Hertz-Picciotto found that women were more likely to have babies with fatal birth defects if they lived within a mile of sites where any of five different classes of toxic pesticides were applied. The incidence of multiple congenital anomalies as well as urinary tract anomalies was “particularly high,” she says, among children whose mothers lived near at least three classes of pesticide applications during the weeks when organs develop.

“These are not benign chemicals,” Hertz-Picciotto says.

The studies add to growing evidence suggesting that these pesticides can scramble signals in the body’s neurodevelopmental and reproductive programs, she says, leading to obvious anatomical defects as well as cognitive changes that are more subtle.

Women can reduce their exposure by washing food thoroughly and using green products in the home, Hertz-Picciotto says. But for involuntary exposures, she adds, there’s not much an individual can do besides moving away from areas of heavy pesticide applications.

* * *

Once the EPA accepts a civil-rights complaint for investigation, officials are obliged to make a preliminary finding within 180 days. The agency missed that deadline by more than a decade, during which time strawberry growers applied more than 780,000 pounds of methyl bromide within a mile and a half of Rio Mesa High School, Department of Pesticide Regulation records show. Finally, on April 22, 2011, nearly twelve years after Maria G. and the five other parents filed their civil-rights complaint, the EPA reached a decision. California pesticide regulators had violated Title VI, the EPA ruled, by approving methyl bromide permits that failed to consider the health impacts on Latino children attending schools near fumigated areas. Even then, however, the agency did not inform the families.

To investigate the complaint, agency scientists had developed an exposure model to predict methyl bromide air concentrations near schools. Although more than a decade had passed since the families had filed the complaint, the EPA restricted its review to the years 1995 to 2001. The agency modeled exposure levels at schools around the state and compared the demographic makeup of schools where exposures exceeded safety targets to that of schools where exposures were considered safe. Based on the analysis, the EPA concluded that methyl bromide applications between 1995 and 2001 resulted in an “adverse disparate impact upon Latino schoolchildren.”

The agency also found that methyl bromide applications during that time exceeded safety thresholds for both short-term and chronic exposures.

Yet, instead of informing the parents behind the complaint of its decision, the agency entered closed negotiations with state pesticide regulators. Four months later, the EPA announced it had entered into an agreement with the pesticide department and “resolved” the complaint.

The agreement required state regulators to continue a pesticide air-monitoring program they had launched in 2006 at a handful of sites, which included a monitor in Oxnard that they would later relocate to Rio Mesa High School. Regulators would also have to add a monitor in a second strawberry-growing region in California’s central coast and produce educational information in Spanish about risks associated with pesticides for communities with the highest methyl bromide use—including how to respond to accidents.

But the agreement was more striking for what it failed to do. The EPA did not require pesticide regulators to ban methyl bromide or require less toxic pest-control measures near schools. It did not require them to expand school buffer zones or change the permitting process to ensure that schools attended mostly by children of color don’t suffer disproportionately from pesticide use. Nor did it take advantage of the powerful weapon Congress gave federal agencies to fight discrimination: the threat of withholding funding until state regulators altered their policies to ensure equal treatment for Latino schoolchildren.

And that was not the only problem. Because methyl bromide was found to deplete the protective ozone layer around the earth, the EPA had banned its production, import and use, except for emergency or “critical” uses, by 2005 under an international treaty. Since strawberry production qualified as a “critical” use, growers had time to wean themselves from the toxic compound. By the time the EPA resolved the complaint, however, growers had mostly given up on methyl bromide and turned to other toxic fumigants that were not covered by the settlement. As growers cut back on methyl bromide around Rio Mesa, they applied nearly half a million pounds of 1,3-D and other hazardous methyl bromide replacements in just the twelve months following the settlement.

“EPA has a really sorry track record on enforcing Title VI,” says CRPE attorney Newell, whose client Maria G. is now using her actual surname, Garcia. “What we have here is an agency that does not have the political will to use the Civil Rights Act to protect people’s civil rights. We have an agency that’s more interested in protecting the rights of growers to use harmful pesticides to pollute communities of color.”

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State regulators still say nothing was wrong. According to Department of Pesticide Regulation spokesperson Charlotte Fadipe, the EPA did not conclude that the department’s policies had been discriminatory, but simply made an “allegation” of discrimination that her agency considers unfounded. “We disputed how the data was collected and how it was used, but rather than fight it, we settled,” she says. “We agreed to put in place some processes, because we felt it was much smarter not to spend state time and money on something that happened fifteen years ago over a chemical that’s been phased out.”

Last year, when the state health department’s Environmental Health Tracking Program released its comprehensive survey of pesticide use near schools, focusing on chemicals with known health risks, Latino children were nearly twice as likely as white children to go to a school near the heaviest applications.

Before the survey came out, Hannah-Beth Jackson, now a state senator, had approached farming interests—which had backed her bill after the Mound school poisoning incident—to support a new bill with even stronger restrictions on pesticide use near schools and other vulnerable sites. But during the two months that the bill was under consideration, trade groups representing the state’s $43 billion agricultural industry had mobilized lobbyists to influence several pesticide bills, including Jackson’s. And although letters urging support for Jackson’s bill outnumbered those opposed by a ratio of six to one, documents obtained through the California legislative open records act show, Jackson’s bill died in committee the day before the health department’s school pesticides report came out.

The health report came as a shock to Ben Todd, who teaches history and social science at Rio Mesa. Todd invited staff to his classroom to discuss what the findings might mean for the students. “We’re entrusted with these kids,” he says. “The health and safety of students comes first. If that’s not taken care of, there’s no way education can take place.”

A few weeks after the meeting, Rio Mesa administrators forwarded a letter to the staff from Ventura County Agricultural Commissioner Henry Gonzales. He argued that the “increasingly strict regulatory framework” governing pesticide use near schools rendered many concerns raised by the California health department report “unwarranted.”

The commissioner’s pesticide enforcement office “places the highest priority on the protection of schoolchildren and any others that may be at risk of exposure to pesticides,” Gonzales wrote. He went on to assert that “proximity to these chemicals does not equal exposure,” just as “you can be near the ocean and not get wet.”

The Department of Pesticide Regulation’s Fadipe echoes those remarks. “This report does not measure exposure, which is the main thing that we’re concerned about,” she says.

Last year, monitors installed at Rio Mesa detected levels of the fumigant 1,3-D in the air at the school. The methyl bromide alternative is classified by the EPA as a probable human carcinogen. (A series by the Center for Investigative Reporting last November showed that state pesticide regulators allowed growers to compensate for the loss of methyl bromide by using twice as much 1,3-D as rules allowed, even though doing so exceeded health limits.) 1,3-D is listed under California’s right-to-know law as “known to the state of California to cause cancer.” Pesticide regulators downplayed the risks, saying safety targets would be exceeded only if the levels continued for seventy years. But several of the readings surpassed those associated with high risks of cancer and other chronic conditions discussed in a 2002 study by California’s Environmental Health Investigations Branch.

For Emily Marquez, a scientist at the advocacy group Pesticide Action Network who assesses exposure risk, detection of 1,3-D raises red flags. “Kids exposed to pesticides through their lifetime have an increased risk for leukemia and other types of cancers,” Marquez says. “What does one year of exposure to a level of 1,3-D that exceeds the agency’s screening levels for cancer risk do to kids at Rio Mesa? We may not know until after they’ve graduated.”

In 2013, Newell and a colleague challenged the EPA’s settlement agreement on behalf of Maria Garcia in US District Court but the case was dismissed. After appealing, Garcia and her attorneys agreed to attempt mediation, but the parties failed to reach an agreement. The case is still pending in the US Court of Appeals for the Ninth Circuit. Agency officials won’t comment on any aspects of the case, says spokesperson Jennifer Colaizzi, because it’s still in dispute—as it has been for nearly fifteen years.

Although so many years have passed, Garcia will still not speak publicly about her case. Neither will her son, who has long since graduated from Rio Mesa. And now, Newell says, Garcia’s two grandchildren will attend Rio Mesa and face the same risks her son did in the late 1990s.

On a hazy day in 2014, just a few feet beyond a welcome sign in Rio Mesa’s parking lot, a chain-link fence held a poster. High winds battered the poster’s edges, allowing only brief glimpses of the dates and times scrawled on either side. The warning at its center was easier to read: “do not enter/no entre, methyl bromide fumigant buffer zone.”

* * *

Dayane Zuñiga, who ran for Oxnard High’s track team, had been investigating the health effects of pesticides for a local grassroots organization when she read the California Department of Public Health report. She was soon organizing an event in front of her alma mater to let people know that, once again, their county’s schools had a higher concentration of nearby pesticide use than any others in the state. On a blustery summer day, typical for the coastal town, Zuñiga walked along the edge of a strawberry field and watched the marching band rehearse on the football field just yards away. Cheerleaders practiced close by.

“None of them are thinking, ‘Oh, there are pesticides there,’” Zuñiga said. “They’re just practicing for their teams.”

She might almost have been watching herself, before she knew better.

Liza Gross reported this story with the generous support of the NYU Reporting Award and the Dennis A. Hunt Fund for Health Journalism and the National Health Journalism Fellowship, programs of the USC Annenberg School of Journalism’s California Endowment Health Journalism Fellowships. She thanks the UC Davis Center for Regional Change for technical support in mapping pesticide use data to ZIP codes.