More than 100 schools in Stanislaus County face pesticide risks. What can be done?
More than 100 schools and child care facilities in Stanislaus County are near areas where agricultural pesticides are applied.
One major concern is pesticide drift — the unintentional movement of pesticide particles or vapors through the air during or after application. Drift can expose nearby residents to harmful chemicals, potentially causing symptoms including eye and throat irritation, nausea and in some cases more serious health effects depending on the chemical involved.
Children are especially at risk. Because their bodies are still developing and they breathe more air per pound of body weight than adults, they are more vulnerable to the effects of pesticide exposure.
Stanislaus County Agricultural Commissioner Linda Pinfold said her office follows state rules about notifying K-12 public schools about planned nearby pesticide use.
Reported exposures near Stanislaus County schools
In the past three years, at least two incidents of alleged pesticide drift have been reported near schools in Stanislaus County.
One such incident occurred at Modesto Christian High School on Jan. 19, 2023, during a fire drill. The incident involved pesticide application from an almond orchard west of the school.
According to the report, 24 people showed symptoms consistent with pesticide exposure and were evaluated by EMTs. Among them, 19 were students, and one student was taken to a hospital.
Pinfold said the timing of the incident was unfortunate. During the investigation, she learned there had been some communication between the school’s maintenance staff and the grower, but she assumes this particular incident was not shared.
“I think growers try to do their best, but how is the grower to know that they were going to be doing a fire drill as well?” Pinfold said.
The investigation was prompted by a Facebook post that reported a hazardous materials issue at the school. The Stanislaus County Agricultural Commissioner’s Office inspectors collected swab and foliage samples from both the school parking lot and the nearby almond orchard the following day. The samples were tested for oxyfluorfen, a restricted herbicide used in the application.
The test results revealed that the swab samples taken from the school came back negative, showing no evidence of oxyfluorfen pesticide drift onto the school grounds. However, the investigation did not test for glyphosate, another pesticide used in the almond orchard.
This was because glyphosate is a widely used herbicide in both agricultural and nonagricultural settings, often applied on school campuses, which could mean it already had been used on the school property. Additionally, investigators were unable to obtain information from the school about its pesticide use.
Additionally, the investigators could not gather medical confirmation or interview individuals with symptoms to directly link those symptoms to pesticide exposure. As a result, the investigation found that the grower did not violate any regulations concerning pesticide application.
“We cannot say that there was drift onto their property. We do not have evidence of that,” Pinfold said.
Mark Weller, campaign director for Californians for Pesticide Reform, said glyphosate should have still been tested for. He also added that more effort could have been made to speak with those experiencing symptoms and to verify the school’s pesticide use.
Pinfold said that even if it were confirmed that the school had not used glyphosate and testing showed a positive result, it wouldn’t prove pesticide drift, because the chemical could have come from another nearby field.
A public charter school neighboring Modesto Christian School, Great Valley Academy, had a similar incident a year later.
On Jan. 26, 2024, Britton Konynenburg Farms applied pesticides using an air-blast sprayer near the school, according to a report. The application was made within a quarter mile of the school, violating pesticide application restrictions.
A GVA employee reported smelling a strong odor and feeling lightheaded after witnessing the application. The employee did not seek medical attention but reported the incident to the school’s maintenance staff.
Swab samples were collected from the school property and analyzed for the presence of copper, the active ingredient in Nu-Cop 50 DF, one of the pesticides used. The analysis revealed a detectable amount of copper in the samples, indicating pesticide drift had occurred.
Britton Konynenburg Farms was issued a violation notice for violating pesticide application restrictions, failing to protect persons and property from pesticide contamination and failing to submit a Pesticide Use Report on time.
Bianca Lopez of Valley Improvement Projects believes that incidents like these, where individuals experience symptoms or become ill, have occurred frequently but often go unreported.
She said the Agricultural Commissioner’s Office should do more to raise awareness that school administrators should contact it when necessary. Regarding the GVA case, the complaint was received by Lopez before being referred to Pinfold’s office.
Valley Improvement Projects, the county and Californians for Pesticide Reform are developing a Pesticide Incident Response Guide for Schools, Lopez added.
What the state requires
To reduce risk, California has implemented several laws and regulations. The Healthy Schools Act, enacted in 2000, requires schools to notify parents annually about expected pesticide use on school property. It also encourages the adoption of integrated pest management strategies using the least toxic, most effective methods to address pest problems.
In 2018, the California Department of Pesticide Regulation introduced additional statewide protections for schoolchildren. These rules require growers to provide written annual notifications to public K-12 schools, licensed day cares and county agricultural commissioners about planned pesticide use within a quarter-mile of school sites.
The notification is simply a list of pesticides that growers plan to use in the upcoming year and does not include details such as the specific day, time or method of application. “It doesn’t give us dates or anything like that that we would want,” Weller said.
Some applications, especially those involving restricted materials — pesticides considered to carry greater risks — must also be reported to county officials at least 24 hours in advance.
Certain application methods also are prohibited within a quarter-mile of public schools and day cares from 6 a.m. to 6 p.m. weekdays. These include aerial spraying, air-blast sprayers, fumigation and most dust or powder applications, which are more likely to drift.
By the end of 2026, these regulations will be expanded to include private K-12 schools with six or more students, in accordance with Assembly Bill 1864, introduced in 2024.
Pinfold said her office isn’t actively encouraging or seeking our private schools to register for notifications since it doesn’t have a full list of private schools in the area. “But if any schools … want to contact us and ask us to register them to be part of that notification, of course, we’re going to do everything that we can to work with them on that,” Pinfold said.
Increasing student protection
Pinfold said her staff has been working with the Modesto Fire Department and local school systems to increase outreach and ensure they understand that the County Agricultural Commissioner Office is a resource to contact.
She also noted that there could be improved communication between schools and growers regarding schedules. For instance, a school might have a football game that starts after 6 p.m., when the buffer zone expires. In such cases, growers could apply pesticides at that time, potentially causing drift onto the football field.
She and her staff are happy to assist schools in reaching out to growers, Pinfold said, but she relies on schools to initiate contact because there is no way for her to know every school’s schedule of outdoor activities.
She has also advised growers that if they want to take a proactive approach to a potentially sensitive situation, they can inform her office in advance. “You’ve got to realize, it’s those growers’ kids who are going to those schools as well,” she said.
Weller argued that buffer zones around schools should be expanded because pesticide drift can extend beyond a mile. He suggests a 2- to 2.5-mile radius would be more effective in protecting students. Additionally, he said he believes the buffer zone should be in place around the clock rather than just from 6 a.m. to 6 p.m.
Moreover, he said all farming within a mile of schools should be organic, which he said would greatly reduce the risks and potential harm to children while they are at school.
“We look forward to a time when all growers, all fields around schools, are organic. And I think that would be the best solution to this,” he said.
This story was originally published May 8, 2025 at 1:57 PM.
