DAVID GREENE, HOST:
There is a medical mystery in North Carolina. In three neighboring towns near Charlotte, the cancer rates are much higher than expected. No one seems to understand why. And as Claire Donnelly reports from member station WFAE, residents are searching for some kind of explanation.
CLAIRE DONNELLY, BYLINE: A Christmas tree with white lights dominates Kenny and Sue Colbert's living room in Cornelius, N.C. A shelf in the corner displays framed family photos, including one of their late daughter, Kenan.
SUE COLBERT: That's her dog, Jetty - her little dog. And Jetty's still living. Jetty is 11 now - 12?
UNIDENTIFIED PERSON: Eleven, yeah.
DONNELLY: Kenan had an eye removed because of a rare form of eye cancer - ocular melanoma. She died five years ago at age 28.
S COLBERT: I never tire of telling Kenan's story and talking to people about her. It's a way that we keep her with us and her memory alive.
DONNELLY: Ocular melanoma affects about six out of every million people. But since 2002, in the towns of Cornelius and Huntersville - combined population 82,000 - researchers have documented at least 16 cases of this rare cancer. The disease typically affects people 50 and older. But all but four were under 50, and seven were younger than 32. Kenny Colbert, Kenan's dad, says many residents are worried.
KENNY COLBERT: A lot of parents who have younger children, you know? My kids are out and about around the entire county. They're swimming in Lake Norman and things. Are they going to be exposed to this?
DONNELLY: Researchers aren't exactly sure why this rare cancer has shown up so frequently in this part of North Carolina. Zack Moore is the state epidemiologist.
ZACK MOORE: There's a lot of things that we're exposed to all the time, so it's hard to know when those exposures might have taken place. For some of those exposures, it can be years or even decades between the time you're exposed to something and the time that you would develop a cancer or be diagnosed with a cancer.
DONNELLY: And those aren't the only towns in this part of North Carolina researchers are concerned about. In Mooresville, about 15 miles away, thyroid cancer is the worry. A health department report found the rate was nearly double compared to the rest of the state between 2012 and 2016. Jenn Harrington (ph) had her thyroid removed after she was diagnosed with cancer in August.
JENN HARRINGTON: I have lost a lot of my energy level. I'm always cold. I'm taking medication three times a day.
DONNELLY: People are starting to take action. One woman, whose daughter was diagnosed with thyroid cancer, has helped raise $100,000 for scientists at Duke University to test the town's water, soil and air. Mooresville is near a coal power plant operated by utility company Duke Energy. Coal ash, a byproduct of burned coal, contains contaminants like mercury and arsenic. On its website, Duke Energy points to decades of research claiming coal ash is not hazardous and does not cause thyroid cancer.
Dr. Clifford Mitchell of Maryland's Environmental Health Bureau says many factors besides the environment can determine whether someone develops cancer.
CLIFFORD MITCHELL: It also depends on your genetic makeup, what your metabolism is like, other risk factors or other exposures that you may have. So it's really complicated.
DONNELLY: As health officials in North Carolina continue to study what's happening and why, people in these towns are forced to keep living with the uncertainty and not knowing why their neighbors keep getting sick.
For NPR News, I'm Claire Donnelly in Charlotte.
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