The search for clues related to cancer cases in the region – specifically ocular melanoma (OM) in north Mecklenburg and thyroid cancer in southern Iredell – recently zeroed in on speculation about the possible dangers of coal ash. But a new report from the N.C. Department of Health and Human Services could shift the focus of the conversation.

The report, distributed in January to Iredell County officials and N.C. General Assembly members representing Iredell, concludes that there are “no published studies to support an association between coal ash exposure and thyroid cancer.”

The DHHS report includes acknowledgement that coal ash can contain radionuclides (chemical elements that emit radiation), and that radiation has been identified as the only environmental element clearly linked to thyroid cancer. But it emphasizes the lack of known ties between coal ash and the cancer.

Topic of discussion

Coal ash and its environmental impacts emerged as topics of discussion in cancer-related conversations in Iredell and Mecklenburg in reference to thousands of tons of coal ash stored at Duke Energy’s coal-fired production plants in the region, coal ash (the leftover product of coal burning) and its use for years as fill material for construction projects, including more than a dozen documented in the Mooresville area.

The practice involved truckloads of coal ash mixed with dirt to create suitable construction sites. Last year, seepage at a fill site off N.C. 150 – where a project had been abandoned before a solid surface concrete foundation or asphalt parking lot had been installed – drew heightened attention to coal ash.

Concerns about coal ash spilled into an ongoing effort to find clues about a statistically- high occurrence rate of thyroid cancer in and around Mooresville, where a researcher from Duke University is exploring potential environmental ties.

And in Huntersville, at the most recent meeting of an advisory board supervising regional research into cases of extremely rare OM, coal ash was again referenced. Zach Hall, director of environmental science for Duke Energy, participated in the meeting and provided details of the company’s constant ash storage monitoring efforts.

But also at that meeting, Kenny Colbert, whose daughter Kenan died in 2014 after a four-year battle with OM, spoke up about the unknowns of coal ash, including how it might react, over time, with soil in a construction site.

Coal ash is referenced in just one section of the 21-page DHHS report, prepared by Zack Moore, state epidemiologist and epidemiology section chief for DHHS; and Chandrika Rao, director of the N.C. Central Cancer Registry.

The report states DHHS officials heard concerns from the community “about the possible contribution of other chemicals to rates of thyroid cancer, particularly those related to coal ash.” And in response, DHHS examined research and literature for links between coal ash and thyroid cancer and found none.

Not a complete research project

The report confirmed the rate of thyroid cancer diagnoses in southern Iredell has been “significantly higher” than the state rate in recent years, but the rate of thyroid cancer cases has been increasing at the state, national and international level during the same timeframe.

The report says that “few differences were seen in age, sex and race of people diagnosed with thyroid cancer” in Iredell compared to people diagnosed elsewhere in the state and country, except in southwestern Iredell (which includes the Lake Norman area) where the average age at diagnosis was “slightly higher” than state and national averages.

Multiple times, the report identifies ionized radiation (often from medical treatments) as a known cause of thyroid cancer. It also references other chemicals – like benzene, nitrates, formaldehyde and flame retardants – that have been linked to some thyroid cancer cases.

The DHHS report states no radiation releases or significant community exposures to radiation were found. But the agency also emphasized its report reflects a compilation of data and “is not a research study.”

“Only a comprehensive research study can provide information about whether exposure to these or other factors might be associated with rates of thyroid cancer diagnosis in Iredell County,” the report states.


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