LADERA RANCH, Calif. (WOWO) — At least six children in a Southern California community have been diagnosed with a rare form of cancer, prompting environmental testing and growing demands from families for answers.

The cases involve Ewing sarcoma, a rare cancer that develops in bone or nearby soft tissue and most often affects adolescents and young adults, according to the National Cancer Institute.

California health officials say they have not identified a specific cause or determined whether the number of cancer diagnoses in Ladera Ranch is higher than would normally be expected.

The California Department of Public Health is conducting a new review of cancer data for the Ladera Ranch area after residents raised concerns about possible environmental exposures, including pesticides and herbicides used around the community.

The investigation gained additional attention after 17-year-old Brody Matteson died in March from complications related to treatment for Ewing sarcoma, according to local reports.

Matteson’s death was followed by other families coming forward about pediatric cancer diagnoses in the community.

Some residents, including Matteson’s father, Dustin Matteson, have questioned whether chemicals used in local landscaping could have contributed to the illnesses.

“We don’t have a clear line of evidence for pesticides, but it is one of the things that concerns us,” Matteson told NBC Los Angeles in July.

The California Department of Public Health previously examined the issue in 2024 at the county level. The agency said that review did not find an unusual cancer pattern, but acknowledged that the information available at the time was limited.

The state is now conducting a more focused assessment of cancer incidence in Ladera Ranch. CDPH estimates that review will be completed in fall 2026, although the agency said the timeline could change depending on the scope of the investigation and additional information that needs to be evaluated.

State environmental agencies have not identified an immediate environmental hazard.

“At this time, our colleagues at CalEPA (California Environmental Protection Agency) and its boards, departments and offices have not identified any immediate environmental hazards,” CDPH said.

The state also said it has not established whether the Ewing sarcoma cases — or other cancer diagnoses reported by residents — are connected to an environmental exposure.

The federal government has become involved as well. In July, First Assistant U.S. Attorney Bill Essayli asked the Environmental Protection Agency to investigate potential environmental factors that could have contributed to the pediatric cancer cases.

Hundreds of residents have attended community meetings as the investigation has expanded.

Ladera Ranch Maintenance Corporation, the community’s master homeowners association, temporarily suspended the use of certain landscape chemicals and created an advisory committee to examine its landscaping practices.

Residents have also reported other cancers, including glioblastoma, but the current state investigation has not determined whether those cases are connected to the Ewing sarcoma diagnoses.

Environmental testing began September 14, when researchers from California State University, Fullerton began collecting soil and water samples from parks throughout Ladera Ranch.

Jennifer Piazza, Ph.D., a professor in Cal State Fullerton’s Department of Public Health, is leading the research team.

“Environmental sampling is the first step of our larger, ongoing scientific investigation,” Piazza told Fox News Digital.

Researchers are testing samples for heavy metals including arsenic and lead, along with pesticides. Piazza said the team expects to have the results by the end of the year.

She cautioned that the testing results alone will not establish whether an environmental exposure caused any of the children’s cancers.

“I also want to emphasize that whatever we find does not imply causality in terms of the pediatric cancer cases in Ladera Ranch,” Piazza said.

LARMAC said it understands residents’ concerns and is cooperating with government investigations.

The organization told People magazine it has “heartfelt compassion to the families who have been affected by these devastating illnesses.”

LARMAC said it was not aware of any government determination identifying a specific environmental cause or connecting the association’s landscaping practices to the illnesses. The organization also said it has reduced its use of synthetic pesticides and moved toward organic pesticides.

Medical experts say the uncertainty is particularly significant in the case of Ewing sarcoma because there is no confirmed environmental or genetic cause known to cause the disease.

Dr. Janet Yoon, a pediatric oncologist and sarcoma specialist at City of Hope in Los Angeles, said the rarity of the cancer makes a geographic cluster worth investigating, while emphasizing that a connection has not been established.

“Knowing that this is a very rare cancer diagnosis amplifies the concerns,” Yoon 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.”

Yoon said there is currently no confirmed genetic or environmental factor known to increase a person’s likelihood of developing Ewing sarcoma.

The American Cancer Society notes that some research has associated occupational or high-level exposure to certain pesticides with increased risks for some cancers, but the evidence varies depending on the chemical and the type of cancer. No known lifestyle-related or environmental cause of Ewing sarcoma has been established.

For parents, one potential warning sign can be persistent pain. Yoon said Ewing sarcoma can initially resemble an ordinary sports injury or growing pains.

“It’s pain that persists. It’s pain that wakes them up from their sleep. It’s pain that limits their daily activities,” Yoon said.

She described cancer as a “great masquerader” in children because the disease is rare and more common childhood complaints can have similar symptoms.

Yoon advised families to have children evaluated when pain persists, worsens or begins interfering with normal daily activities, and said specialized cancer centers with experience treating sarcomas can help with diagnosis.

The Ladera Ranch investigation remains ongoing. State officials have not established that pesticides, herbicides, landscaping practices or another environmental factor caused the cancer cases, while researchers continue gathering data and testing samples for potential exposures.