CHARLOTTE (AP) â€” State regulators this year have cited 15 of roughly 90 of North Carolinaâ€™s largest water systems including Lincoln County for releasing too many toxic chemicals into their water.
The chemicals arenâ€™t immediately harmful, the Environmental Protection Agency says, but people who drink water containing them for several decades may face a greater cancer risk.
Among the systems cited are those in Statesville, Monroe, Kannapolis, Lincoln County and Union County.
The toxins are the result of disinfection released into water systems, which makes drinking water safe from disease-spreading bacteria and viruses. But it also creates toxins in some water, called disinfection byproducts.
The byproducts form when naturally occurring matter in water, such as soil or leaf debris, reacts with chlorine or other disinfectants.
The EPA, followed by North Carolina in 2000, set lower drinking-water limits for one class of those chemicals â€” trihalomethanes â€” and set new limits for a second class called haloacetic acids.
Surface-water systems serving 10,000 or more people had to meet new limits in January 2002. Because compliance is based on running yearlong averages, calculated every three months, violations werenâ€™t cited until this year.
Through September, 15 systems of that size have been cited for violations in at least one quarter involving one or both classes of chemicals. Southern Pines, Albemarle, King and Rockingham racked up violations in each of the yearâ€™s first three quarters.
Groundwater systems and surface-water systems serving fewer than 10,000 people have to meet the same limits starting in January. About 2,200 N.C. systems are in that class.
Systems with violations must notify customers within 30 days. The notices, written by the state public water supply section, say the violations pose no immediate risk. Customers are not advised to switch to bottled water.
â€œWe had quite a bit of response to it, especially on the eastern side of the county,â€ said Larry Warren of the Lincoln County system, which broke the haloacetic acid limit in July.
Chlorinating the water later in the treatment process cured the problem, he said.
A half-dozen former cancer patients came to talk about the notices. â€œI was able to relieve some of their fears,â€ said Warren, himself a seven-year cancer survivor.
Both classes of disinfection byproducts include chemicals that probably cause cancer after many years of exposure, the EPA says.
Trihalomethanes can also harm the liver, kidneys and central nervous systems. But state toxicologist Kenneth Rudo said recent studies indicate trihalomethanes arenâ€™t as dangerous as once thought.
â€œA few years ago we would have looked at these levels as being of concern,â€ he said. New data, he added, â€œshows it is not as much a problem from a toxicity standpoint as we thought it was.â€
Less clear is the effect of haloacetic acids, he said. The state needs to see how levels rise and fall over time, he said.
Diane Williams, the official in charge of the rule for the state public water supply section, said the weather helped form the chemicals.
With less water moving through pipelines during last yearâ€™s drought, she said, water temperatures rose, stimulating formation of trihalomethanes. Later, heavy spring rainfall lowered pH levels, prompting more haloacetic acids to form.
Systems can fight the chemicals with steps, she said, such as applying chlorine later in the water-treatment process and reducing accumulations of organic sediment in reservoirs.
Statesville, cited for violations twice this year, believes drought caused the compounds to form in its water system.