Wealthy Orange County Community Suspects Pesticides in Rare Bone-Cancer Cluster

A cancer cluster in Ladera Ranch, a wealthy Orange County neighborhood, has raised alarm bells for residents who are demanding that the Homeowners Association (HOA) halt the current pesticide regimen, which includes Lifeline (glufosinate-ammonium), Atrimmec (a growth regulator), and Specticle G (indaziflam). The community has a population of 23,000-26,000 and has seen 9-12 cases of rare cancers known as Ewing sarcoma and synovial sarcoma.

Ewing sarcoma affects only 200-240 children nationwide each year, or about three cases per one million children and teens. This community has had six to nine cases since 2013, with an approximate population of 8,400 residents under 18. Six cases over a 13-year period is about one case per 1,400 children. Nationally, the approximate rate of Ewing sarcoma over a 13-year period is one out of 25,000 children. Unofficial calculations based on a static child population show the community has a 15-20x higher risk of Ewing sarcoma compared to the national rate.

No official confirmation has determined that pesticides caused the cancer cluster, but an investigation is underway. The New York Post reported on the HOA’s board meeting, which included statements from Santa Margarita Water District board member Margaret Novak, who said traditional pesticides are needed so the landscape looks pretty. The Post reported a mother who lost her son to cancer earlier this year was “visibly shaken and began crying during Novak’s speech.”

The HOA implemented a 60-day temporary pause on certain landscaping products on July 17, but continued to spray Specticle G Herbicide, which contained the primary ingredient indaziflam. Bayer Crop Science attempted to register the chemical internationally in 2010, but it did not receive approval in Europe. The HOA added that chemical to the temporary ban list and extended the pause to 120 days, which expires at the end of November.

The cancer cluster is concerning to residents, and they have called for an independent investigation and a permanent ban on traditional pesticides. Resident and prospective HOA board member Jeff Moll told the Post that the community already spends $44,000 a month on certified landscape.

The board did unanimously approve a new organic landscaping plan that expands the areas designated as “high-use” where synthetic pesticides will not be sprayed. Parents in the community are not satisfied with anything short of a full ban on the concerning chemicals. They say their children walk in areas other than sidewalks and designated paths, so they are still likely to be spending time in areas labeled as “low-use.”

Glufosinate and Indaziflam are all labeled as “not likely to be carcinogenic” and do not contain labels that state there is a cancer risk associated with these products. The granular formulation of Specticle G states that the product “may cause cancer,” but it is not due to the primary active ingredient of indaziflam. The cancer risk is associated with the “respirable crystalline silica in the granule carrier.”

While there isn’t scientific literature demonstrating a cancer risk associated with these specific herbicides, there are epidemiological studies that find an association between pesticide exposure and various forms of cancer. A 2024 study concluded, “Pesticides have a significant effect on increasing cancer risk for all the cancer types evaluated.” The study did not include the specific pesticides used by the Orange County community, and it did not evaluate Ewing sarcoma, a very rare form of cancer.

First Assistant U.S. Attorney Bill Essayli asked EPA administrator Lee Zeldin in July to investigate possible environmental factors and whether federal environmental laws have been violated. Orange County Supervisor Katrina Foley asked the California Department of Public Health to expedite its review. State legislators representing the area requested a joint look at pesticide application records, soil and water, and updated cancer-registry data. The Orange County Health Care Agency convened the Cancer Registry, UC Irvine’s cancer center, and the county agricultural commissioner for an updated data review.

Cal State Fullerton researchers collected soil and water at three parks in mid-September. NBC Los Angeles reported USC researchers agreed to study the sarcoma cases.

Two epidemiologists wrote an op-ed for the Orange County Register stating that case counts do not prove there is a cluster and that the denominator must include the children who have lived in the area dating back to 2007, when the first sarcoma case was diagnosed in Ladera Ranch. They state that random clustering can occur within a large country, but it doesn’t prove there is an environmental exposure causing harm. The authors said they support an investigation if Ewing sarcoma numbers are elevated within the Ladera Ranch community. They also note that there is high pesticide usage across California and no other apparent Ewing sarcoma cancer clusters in other areas.

The epidemiologists cited past case studies in which officials investigated cancer clusters but could not find an environmental cause. The authors referenced a 2012 review of 20 years of investigations that concluded: “it is fair to state that extensive efforts to find causes of community cancer clusters have not been successful.” They state that small absolute numbers of cases make it difficult to find a causal link. Around the year 2000, an investigation into 16 childhood cases of leukemia in Fallon, Nevada came up with no clear cause for the apparent cluster. The town would have only expected one or two cases during that time frame.

Meanwhile, the EPA is working to complete its hazard assessment on glyphosate’s risk to human health. The agency has released an open search literature document of the glyphosate research it is going to use in its evaluation and is providing the public an opportunity to submit comments until September 24, 2026, with other literature it should consider in the review process. The EPA plans to complete the review by the end of the year.