CASTAIC, Calif. — A Los Angeles County supervisor and the public health director is asking  for assistance Friday to evaluate claims by residents that the Chiquita Canyon Landfill in Castaic has led to a cluster of cancer cases.

Supervisor Kathryn Barger and county Public Health Director Barbara Ferrer sent a joint letter to the Los Angeles County Cancer Surveillance Program to evaluate the situation.

"Since this crisis began, I have led our county's efforts to provide real-time response and action to the impacted communities," Barger said in a statement released Thursday. "Residents in Val Verde, Castaic, and surrounding neighborhoods deserve real solutions. I will continue to take every concern seriously and remain committed to investigating all concerns raised by the community."

At a news conference Tuesday, a group of residents said toxic fumes from the troubled landfill have led to a cluster of cancer cases. Residents have long complained about ailments such as headaches, burning eyes, rashes and nausea due to the landfill.

The South Coast Air Quality Management District has issued abatement orders at the site, but residents say the issues are persisting.

Assemblywoman Pilar Schiavo, D-Chatsworth, said previously that seven people have been diagnosed on a single street of 14 homes in the area, and one of those people has died.

Landfill officials have said odors from the facility are due to "an abnormal biotic or abiotic process, also known as a landfill reaction, taking place deep within a lined but older and inactive portion of the landfill waste mess."

The Los Angeles County Cancer Surveillance Program was created in 1972 and is operated by the Keck School of Medicine at USC.

"The concerns regarding cancer clusters are serious," Barger and Ferrer wrote in the letter to the program. "Identifying increases in cancer cases and ... causes can be challenging. Given your expertise in analyzing cancer trends, we believe your insights will be invaluable."