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What Pesticides Are Sprayed On Almond Orchards, And Are They Harmful To Those Who Live Nearby?

U.S. Department of Agriculture

“Hi, my name is Beverly Thomassian and I want to know what pesticides they are spraying on the almond orchards throughout the year and if they’re harmful to the humans living adjacent to the orchards.”

This was something I also wondered since moving to Chico several years ago. Fortunately, California keeps meticulous data on which pesticides are used throughout the state. I was able to find the top five pesticides used on almonds in Beverly’s neighborhood with the state’s Agricultural Pesticide Mapping Tool. They’re Ziram, Oryzalin, Glyphosate, Paraquat Dichloride, and Clarified Hydrochloric extract.

Since You Asked is a series that answers your questions about the North State. Submit your question by calling 530-433-4887 or emailing

There are many different types of pesticides that growers apply to almonds orchards throughout the year, though predominantly during the spring. Many of these chemicals are very dangerous if used incorrectly, which is why there are so many rules and regulations around their use. Growers must assure that they are safely applying these chemicals. The state also labels the more dangerous pesticides as Restricted Materials. Applicators have to be trained and permitted in order to even purchase them.

Lisa Blecker trains applicators in pesticide safety across the state. She’s with the University of California Davis’ Agriculture and Natural Resource Department. She says that it’s illegal to spray on people, private property and animals.

“It is illegal to spray on them,” Blecker said. “There is no set distance, so even if someone is a mile down the road and you spray on them, you’re liable for that.”

Even if growers follow all the rules, things can go wrong. In an educational pamphlet on pesticide drift, the Department of Pesticide Regulation states that quote “some off site movement occurs with every application, even if only a few molecules.”

Data sourced from the California Department of Pesticide Regulation Pesticide Use Report Database and the California Environmental Health Tracking Program Agricultural Pesticide Mapping Tool.

Rebecca Schmidt is a molecular epidemiologist with the University of California Davis. She and her colleagues looked at some of the risks associated with living near areas where agricultural pesticides are used. Part of that study was done locally. A number of women from the Yuba City area participated.

“We found that moms that had the highest associated risks of having a child with autism were the moms who were exposed to almost any of these types of pesticides and the combination of having not taken a prenatal vitamin or having low folic acid, in the early months,” Schmidt said.

The pesticides Schmidt looked at in her study were chlorpyrifos, organophosphates, and pyrethroids. Previous studies have also found a link between autism and agricultural pesticides. Chlorpyrifos is used throughout our region and it’s been the topic of much debate. A number of activist groups in California are pushing for an outright ban.

Schmidt says that the state does take findings like hers into consideration when making regulations, but she says that the science is often a step behind. Even when a product is banned the replacement isn’t necessarily safer.

“They often replace it with something else that hasn’t been tested for long-term human neural developmental effects, so we end up doing the science to see whether that is still an issue or not with the new product,” she said.

Here in California, the Department of Pesticide Regulation (DPR) and the California Environmental Protection Agency (EPA) decide which pesticides are allowed to be used in the state. Charlotte Fadipe is a spokesperson for the DPR. She says that the state reassesses the safety of pesticides as new information becomes available. A panel of nine independent scientists known as the scientific review panel is currently looking over the available data on chlorpyrifos. This could lead to more restrictions by December of 2018.  In the meantime, the DPR is recommending that county agriculture commissioners increase the distance between where the pesticide can be used and sensitive sites, such as schools and homes.

The county agricultural commissioner is also responsible for making sure that everyone follows the rules. Katharine Quist is the deputy agricultural commissioner for Butte County, where Beverly lives.

“This year alone we’ve done about 350 inspections and we haven’t had very many violations, only about 30 violations on those 350 inspections,” Quist said.

The commissioner's office can give out up to 50 violations per inspection. Quist says that for the most part, people are abiding by the rules.

Data sourced from the California Department of Pesticide Regulation Pesticide Use Report Database and the California Environmental Health Tracking Program Agricultural Pesticide Mapping Tool.

If you are worried about pesticide use next door, calling up your neighboring farm may help to alleviate some of these concerns. They can tell you everything they are doing to prevent drift. They may even be willing to notify you before they spray, so that you can shut your windows and stay inside. There are also several things you can do to monitor for drift. Be aware of unusual smells, paraquat products, for example, have a non-hazardous odour that will alert you to it presence. Observe when pesticides are being applied. In general it shouldn’t be windy. If you do notice a violation, you can call the county agricultural commissioner. They are responsible for investigating complaints.

Additional Resources

Use the following resources to learn how to read product labels, determine how safe a pesticide is and monitor for drift.

National Pesticide Information Center:
Agrian Label Lookup:
Pesticide Action Network:

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