What Is in Coal Ash?
Coal ash — technically known as coal combustion residuals (CCRs) — is the toxic byproduct left after coal is burned to generate electricity. It includes fly ash (fine particles captured by smokestack filters), bottom ash (heavier material that falls to the furnace floor), boiler slag, and flue gas desulfurization sludge. When coal is burned, the trace toxic elements present in coal become concentrated in the ash — often at levels 5 to 10 times higher than in the original coal. A single coal plant can produce millions of tons of ash over its operating life, and this material has historically been stored in unlined ponds and landfills where toxic constituents leach into groundwater over decades.
The EPA has identified the following contaminants of concern in coal ash: arsenic (a known human carcinogen), hexavalent chromium (the Erin Brockovich chemical — a potent carcinogen), lead, mercury, cadmium, selenium, boron, molybdenum, thallium, cobalt, lithium, manganese, antimony, beryllium, and radioactive isotopes of radium and uranium. These are not theoretical risks — they have been measured at dangerous concentrations in groundwater at coal ash sites across the United States.
Cancers Linked to Coal Ash Exposure
Epidemiological studies and EPA risk assessments have linked chronic exposure to coal ash contaminants to multiple cancer types. Arsenic exposure is associated with cancers of the skin, lung, bladder, kidney, and liver — the International Agency for Research on Cancer (IARC) classifies arsenic as a Group 1 human carcinogen. Hexavalent chromium (Cr(VI)) causes lung cancer through inhalation and has been linked to stomach and intestinal cancers through ingestion of contaminated water — it is the same chemical that contaminated Hinkley, California's water supply in the case made famous by Erin Brockovich. Cadmium is linked to kidney and lung cancer. Radium and other radioactive constituents in coal ash contribute to cumulative radiation exposure that increases cancer risk over a lifetime of exposure.
The EPA's own 2010 risk assessment found that living near an unlined coal ash pond and drinking contaminated groundwater creates a cancer risk as high as 1 in 50 — nearly 2,000 times above the EPA's acceptable risk threshold of 1 in 1,000,000. This stunning finding was a primary driver of the 2015 Coal Combustion Residuals Rule.
Arsenic: The Primary Cancer Driver
Arsenic is the contaminant of greatest concern in coal ash. Inorganic arsenic — the form found in coal ash leachate — is a proven human carcinogen at any level of exposure. There is no safe threshold. Chronic low-level arsenic exposure through contaminated drinking water causes a distinctive pattern of cancers: bladder cancer (risk increases 3-7 times at exposures above 50 ppb), kidney cancer, liver cancer, lung cancer (even without inhalation — ingested arsenic reaches the lungs through the bloodstream), and skin cancers including squamous cell carcinoma and basal cell carcinoma. Arsenic also causes a pre-cancerous skin condition called arsenical keratoses — distinctive hard bumps on the palms and soles that are a clinical marker of chronic arsenic exposure.
The EPA maximum contaminant level (MCL) for arsenic in drinking water is 10 parts per billion (ppb), reduced from 50 ppb in 2001. Many private wells near coal ash sites have tested at levels of 20, 50, or even 100+ ppb — far above the MCL and in the range associated with significantly elevated cancer risk. Because arsenic is tasteless, odorless, and invisible, well owners have no way of knowing their water is contaminated without laboratory testing.
Hexavalent Chromium: The Erin Brockovich Chemical
Hexavalent chromium (Cr(VI)) is a potent carcinogen found in coal ash leachate. It is the same chemical that contaminated the drinking water of Hinkley, California — the case immortalized in the film Erin Brockovich. Hexavalent chromium causes lung cancer through inhalation (established in occupational studies of chromium workers) and is increasingly linked to stomach and gastrointestinal cancers through ingestion of contaminated water. A landmark 2008 National Toxicology Program study found clear evidence that hexavalent chromium causes cancer in laboratory animals when ingested in drinking water, and in 2010 an EWG study found hexavalent chromium in the drinking water of 31 of 35 U.S. cities tested. Coal ash is a significant source of hexavalent chromium contamination in groundwater near power plant sites.
Children's Health Risks
Children are disproportionately vulnerable to coal ash contaminants. Their developing bodies absorb a higher percentage of ingested lead, arsenic, and other metals than adult bodies. Lead exposure — even at low levels — causes irreversible neurological damage, reduced IQ, behavioral problems, and learning disabilities. Arsenic exposure during childhood is associated with increased cancer risk later in life, impaired cognitive development, and immune system suppression. Mercury exposure during pregnancy and early childhood causes developmental delays and neurological damage. Children living near coal ash sites who drink contaminated well water, play in contaminated soil, or attend schools built on or near coal ash disposal areas face a lifetime of accumulated toxic exposure during their most vulnerable developmental years.
Reproductive and Neurological Harm
Beyond cancer, coal ash contaminants cause a range of serious non-cancer health effects. Arsenic exposure is linked to cardiovascular disease (heart attacks and strokes), diabetes, peripheral neuropathy (nerve damage causing numbness and tingling in hands and feet), and immune suppression. Lead causes hypertension, kidney damage, and reproductive harm including reduced fertility, miscarriage, and low birth weight. Mercury is a potent neurotoxin that causes tremors, memory loss, and cognitive impairment in adults and devastating developmental effects in children exposed in utero. Selenium at high concentrations causes selenosis — a condition marked by hair loss, nail brittleness, nausea, and neurological symptoms. Boron exposure is associated with reproductive toxicity in animal studies, with concerns about similar effects in humans at high exposure levels.
Latency Periods and the Importance of Early Action
The latency period between coal ash exposure and cancer diagnosis can range from 10 to 40 years. Arsenic-related bladder and kidney cancers typically appear 15-30 years after the onset of chronic exposure. Hexavalent chromium-related lung cancer has a latency period of 10-20 years. This long latency means that people who drank contaminated well water in the 1990s and 2000s may only now be receiving cancer diagnoses linked to that exposure. The latency period also has legal implications: statutes of limitations generally begin running from the date of discovery of the injury and its connection to the contamination, not from the date of exposure. If you have lived near a coal ash site and have been diagnosed with cancer — particularly kidney, bladder, liver, or lung cancer — you should consult an attorney immediately to preserve your legal rights before the applicable statute of limitations expires.
Related Pages
Coal Ash Contamination Lawsuit Lawsuit
Coal combustion residuals — commonly called coal ash — are the second-largest industrial waste stream in the United States, behind only mining waste. Every coal-fired power plant in the country produces coal ash, and the utility industry has disposed of it for decades by dumping it into unlined surface impoundments (wet ash ponds) and dry landfills, many of them sited directly above drinking water aquifers. The toxic constituents of coal ash — arsenic, hexavalent chromium, lead, mercury, selenium, cadmium, boron, and naturally occurring radioactive materials — migrate through soil into groundwater over time, especially from unlined ponds where water constantly percolates through the ash and carries dissolved metals into the subsurface. Duke Energy is the primary corporate defendant in coal ash contamination litigation. The company operates the largest fleet of coal-fired power plants in the United States and maintains more than 17 coal ash disposal sites in North Carolina alone. The North Carolina Department of Environmental Quality (DEQ) and independent testing have confirmed that groundwater at virtually all Duke Energy coal ash sites in the state exceeds safe drinking water standards for one or more heavy metals. Thousands of households near these sites rely on private wells — which are not subject to the public water supply testing requirements of the Safe Drinking Water Act — and many consumed contaminated water for years before the extent of the problem became known. The Tennessee Valley Authority (TVA), American Electric Power (AEP), Dominion Energy, and other major utilities face similar claims in their respective service territories. The legal landscape shifted dramatically after the 2014 Dan River spill, when a stormwater pipe beneath a Duke Energy coal ash pond at the retired Dan River Steam Station collapsed and released 39,000 tons of toxic ash and 27 million gallons of contaminated water into the Dan River. The disaster prompted federal criminal charges, a $102 million settlement, and the passage of North Carolina's Coal Ash Management Act requiring excavation of high-risk sites. The EPA finalized the Coal Combustion Residuals Rule in 2015 — the first-ever federal regulation of coal ash disposal — and strengthened it in 2024 to cover legacy surface impoundments that had previously been exempted. Individual plaintiffs in communities near coal ash sites are now pursuing cancer claims, medical monitoring, property damage, and diminished property value lawsuits against Duke Energy and other utilities.
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