Expert faults EPA on lead

Chemical change cited in Durham water tests

Staff WriterJune 30, 2006 

  • Virginia Tech engineering professor Marc Edwards says Durham's water is not corrosive in ways normally expected in off-kilter public water supplies. He found no problems with pH, alkalinity or the working of chemical corrosion inhibitors.

    What he did find was an imbalance between two chemicals: chloride and sulfate. He blames the imbalance on a switch Durham made in 2003 at one water plant. Changing a chemical used to extract organic materials at the site, the utility may have increased the amount of chloride in the water compared to sulfate. The high ratio produces a charge that can lift lead off solder used to connect lead pipes.

    Houses in North Carolina at greatest risk of lead corrosion are those built in 1983, 1984 and 1985, the year lead solder was banned here. Those homes may not be old enough to have built up protective films in their pipes. Also at risk are homes with lead plumbing components.

    Taps with very high levels of lead are probably rare, Edwards says. But water in any building with lead in the plumbing should be considered at risk until a test says otherwise.

    Durham water officials recommend that their customers run water for three to five minute before consuming it and that they cook with cold water, not warm. They also recommend that people routinely clean aerators in the kitchen taps to be sure none are clogged with toxic plumbing parts.

    In addition, particles captured in tap aerators can be tested for lead using inexpensive kits sold at hardware and home improvement stores. Water filters can also screen out lead, and Edwards recommends those certified for lead removal by the National Sanitation Foundation. Many sell for less than $100.

After conducting tests in Durham, a Virginia scientist says a change in water cleansing chemistry likely caused lead contamination in multiple homes.

Similar problems with lead-tainted water might be evading detection elsewhere in Durham -- and at residences across the country, the researcher concludes. And he blames inadequate testing required by the U.S. Environmental Protection Agency, the agency that is supposed to keep drinking water clear of lead.

"A lead poisoning could happen anywhere," said Marc Edwards, an engineering professor at Virginia Polytechnic Institute and State University. "No one should construe government lead rules as a guarantee that their tap water is safe."

Terry Rolan, director of Durham's water department, said Thursday that his utility will investigate Edwards' conclusions, detailed in a technical report. But Rolan stressed that he is not convinced Durham has a widespread problem on its hands.

"I think it's something we look into and we should investigate. But I can't jump as far as he jumps," Rolan said, stressing that a change in water chemistry will affect one system differently from another.

Durham may be better protected than other cities, Rolan said, because its water department has used chemical films to protect residential piping from leaching lead longer than any other state utility.

Edwards was commissioned to analyze water in Durham last month by WHH Trice & Co., which manages Penrith Townhomes. County health investigators say a child developed lead poisoning from water consumed in a Penrith rental unit.

The poisoning occurred even though EPA-required water tests of 92 homes citywide in 2004 turned up no evidence of a lead problem in Durham's water. But aggressive investigations by county and state public health officials after the Penrith poisoning appear to be finding problems the city missed, Edwards said.

Initially, city water officials announced that any problem in Durham was confined to Penrith plumbing. But water tests arranged by county health officials revealed elevated lead in homes located outside the complex, too. A state survey started this month has detected high lead elsewhere in the city.

Extent of threat questioned

EPA officials, however, say there is no evidence of a huge public health threat originating from lead in drinking water. Rates of lead poisoning in children have declined for years, noted Veronica Blette, special assistant to the EPA director of the Office of Ground Water and Drinking Water.

"[Edwards] wants to say there is an emerging problem," Blette said. "But I don't see the percentage of children with elevated lead in their blood increasing."

This is the second North Carolina city where Edwards has traced a lead problem to a chemical imbalance caused by water cleansing additives. Earlier this year he found a similar problem in Greenville. Water collected from the home of a lead-poisoned boy produced pasta containing more lead per serving than lead in dime-sized paint chips, he said.

A water treatment expert funded by the National Science Foundation, Edwards says a chemical combination found in some municipal water supplies can make the water highly corrosive. The trouble arises when there's too much chloride compared to sulfate.

Edwards has shown in laboratory studies that a high ratio between chloride and sulfate pulls particles of lead off exposed solder used to seal copper pipes before 1985, when lead solder was banned in this state.

Lead, even in small quantities, can harm the mental development of children younger than 6.

Edwards advises city residents to consider any home built with lead solder at risk of lead contamination until a reliable test proves water safe.

Looking for guidance

In 2003, Durham changed the chemical it uses to extract organic materials from water at one of two city treatment plants -- the Brown plant on Infinity Road. The amount of chloride compared to sulfate in water released at the Brown plant increased. The ratio at the Williams plant, located on Hillandale Avenue, changed very little.

Because the water is blended at many spots in the distribution system, it's difficult to say which plant produces the water in any given city tap, Rolan said. The Durham utility has scratched plans to make the same switch at the Williams plant until it investigates Edwards' claims, he said.

Edwards said he found a problem with lead tests conducted by the Durham water system. The utility instructs people participating in tests to remove the aerators on their kitchen taps the night before they take a sample first thing in the morning. That could remove trapped lead particles and overlook a possible source of contamination, he said.

Durham does that because the EPA advises people to clean aerators periodically to remove trapped plumbing debris, said Vicki Westbrook, manager of regulatory compliance for Durham's water management department.

Edwards said EPA guidance on how to analyze lead content in water samples might not be adequate. EPA recommends using a strength of nitric acid that doesn't dissolve some lead particles, he said.

Blette said EPA is re-evaluating aspects of its lead testing rules. It is doing so to better address elevated levels of lead in drinking water in Washington, D.C., and Greenville after changes in cleansing chemistry.

Missy Valentine wants the experts to straighten all this out soon. The Chapel Hill art teacher lives on Loyal Avenue near Penrith Townhomes. She is six months pregnant with her first child. A Durham County test discovered elevated lead levels at her kitchen tap. Now she drinks only bottled water.

"This has been the scariest part of the pregnancy by far," she said.

Staff writer Catherine Clabby can be reached at 956-2414 or cclabby@newsobserver.com.

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