A cluster of rare cancer diagnoses has sparked concern and prompted environmental testing in Ladera Ranch, California, although state health officials say no specific cause has been identified.
At least six children in the area have been diagnosed with Ewing sarcoma, according to federal officials and local reporting.
This exceptionally rare cancer, which forms in the bone or nearby soft tissue, primarily occurs in adolescents and young adults, per the National Cancer Institute.
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“Knowing that this is a very rare cancer diagnosis amplifies the concerns,” Dr. Janet Yoon, a pediatric oncologist and sarcoma specialist at City of Hope in Los Angeles, told Fox News Digital. “Anytime you hear of cases in a geographic location, it does raise some concerns … I can completely understand why further investigation is being done.”
Following the March 2026 death of 17-year-old Brody Matteson from complications of treatment for Ewing sarcoma, more families began speaking publicly about rare cancer diagnoses in the community, according to local reports.
Some residents – including Matteson’s father, Dustin Matteson – have suggested the illnesses could be linked to the community’s use of herbicides and pesticides, which prompted calls for a broader environmental investigation.
“We don’t have a clear line of evidence for pesticides, but it is one of the things that concerns us,” Matteson said to NBC Los Angeles in July.
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In 2024, prompted by residents’ concerns, the California Department of Public Health conducted a county-level review in an attempt to determine whether pesticide use in the community could have played a role in the development of certain cancer types.
“That analysis did not find an unusual pattern at the county level, but the data available at the time was limited,” the CDPH stated on its website.
The agency is now conducting a second review of cancer incidence data for the Ladera Ranch area.
“CDPH currently estimates the assessment will be completed in fall 2026, although the timeline may change based on the scope and complexity of the review and any additional information that may need to be evaluated,” the agency stated.
“At this time, our colleagues at CalEPA (California Environmental Protection Agency) and its boards, departments and offices have not identified any immediate environmental hazards.”
The CDPH stated that it is not yet known whether diagnoses of Ewing sarcoma and other cancer types are higher than expected in the Ladera Ranch community – or whether environmental factors can increase the risk.
In July 2026, First Assistant U.S. Attorney Bill Essayli asked the Environmental Protection Agency to investigate possible environmental factors that could have contributed to multiple pediatric cancer cases.
Over the summer, hundreds of residents gathered at community meetings. At the same time, Ladera Ranch Maintenance Corporation (LARMAC) – the master homeowners association (HOA) for the planned community of Ladera Ranch in Orange County – temporarily paused its use of certain landscape chemicals and formed an advisory committee to review its landscaping practices.
As the investigation has continued, some residents have also publicly reported diagnoses of other cancers, including glioblastoma, although the current state review has not established whether those cases are related.
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On Sept. 14, California State Fullerton researchers began collecting soil and water samples from local parks as part of the environmental investigation.
Jennifer Piazza, Ph.D., professor in the Department of Public Health at Cal State Fullerton, assembled a team of researchers to help address the environmental concerns stemming from the pediatric cancer cases.
“Environmental sampling is the first step of our larger, ongoing scientific investigation,” she told Fox News Digital. “We are collecting soil and water samples across Ladera Ranch. They are being analyzed for heavy metals, such as arsenic and lead, as well as pesticides.”
The team expects to have results by the end of the year, Piazza said.
“I also want to emphasize that whatever we find does not imply causality in terms of the pediatric cancer cases in Ladera Ranch,” she added.
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LARMAC released a statement to People magazine, extending its “heartfelt compassion to the families who have been affected by these devastating illnesses.”
“LARMAC takes these concerns seriously. We are aware that public health agencies are reviewing available information, and we will continue to cooperate with those efforts and follow guidance provided by the appropriate health and regulatory authorities.”
“At this time, we are not aware of any determination by those agencies identifying a specific environmental cause or linking the Association’s landscape management practices to these illnesses,” the statement read.
The organization also noted that it has reduced the use of synthetic pesticides and switched to organic pesticides.
“With Ewing sarcoma, there is no confirmed genetic or environmental cause that we know of,” Yoon told Fox News Digital.
“We have not found any confirmed genetic or environmental factor that increases the likelihood of developing Ewing sarcoma.”
Some studies have linked occupational or high-level exposure to certain pesticides with an increased risk of several cancers, although the evidence varies by chemical and cancer type, according to the American Cancer Society.
No known lifestyle-related or environmental cause of Ewing sarcoma has been identified, the ACS states.
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The disease most often presents as persistent pain rather than a typical sports injury or growing pain, according to Yoon.
“It’s pain that persists. It’s pain that wakes them up from their sleep. It’s pain that limits their daily activities.”
The doctor called cancer the “great masquerader” in children due to its rarity. “Growing pains are much more common than cancer,” she added.
Yoon encouraged families to seek medical evaluation if pain is persistent, worsening or interfering with normal activities. Specialized cancer centers with sarcoma expertise can help ensure an accurate diagnosis, she advised.
