Study of D.C. water sharpens understanding of lead threat
Saturday, December 11, 2010; 10:01 PM
The latest research on the District's decade-long effort to reduce lead in its drinking water is likely to reverberate well beyond the city's borders and add a chapter to one of the more tortuous public health chronicles of the past century.
A report released this month by the Centers for Disease Control and Prevention said the water supplied to almost 15,000 homes might still contain dangerous levels of lead despite the partial replacement of lead pipes at the homes from 2004 to 2008.
The findings called into question what was once one of the city's chief methods of mitigating lead contamination of drinking water. The federal government ordered the District's water authority - now called D.C. Water - to carry out those replacements, but the CDC study found that they didn't solve the problem.
Lead poisoning was once thought to be a serious threat only when it caused such dramatic problems as personality changes, anemia and kidney failure. But lead is now considered a toxin for which there is no safe level, especially in small children. For them, even low concentrations in the blood are associated with reduced IQ, attention deficit and antisocial behavior.
As evidence of lead's hazards accumulated over 50 years, reducing exposure became an important, expensive and contentious goal of government. Lead was removed from gasoline. Lead paint was banned. Children, particularly those living in dilapidated housing in old cities, were tested regularly, and doctors and public health officials stepped in to protect those whose "lead burden" was high.
Now, thanks to the new study, this much is clear: Even when the known exposures to lead are minimized and a city meets the federal government's safety standards, some children may be getting a worrisome amount of lead from the water they drink.
"This really means that the whole way that we've thought about this problem, and have developed public health policies to address it, has to change," said Ellen Silbergeld, a professor at the Johns Hopkins Bloomberg School of Public Health, who serves on a working group of the federal government's Advisory Committee on Childhood Lead Poisoning Prevention.
"We're spreading the word about it [the report]. It went out to our members as a hot news item," said Steve Via, head of regulatory affairs for the American Water Works Association, whose membership includes 4,100 water systems serving about 80 percent of the U.S. population.
'A really big deal'
The source of the problem is no secret. It is lead pipes, some dating from the 1800s, that run from water mains under the street up to houses.
Although water entering a house through a so-called lead service line is exposed to the toxic metal along the entire length of the pipe, municipal water systems own - and control - only the section from the main to the homeowner's property line. If a city's water violates federal lead standards, the first thing the water system must do is treat the water to make it less corrosive and less likely to leach lead from pipes and solder. If that doesn't work, the Environmental Protection Agency orders cities to replace the public part of lead service lines.
But as it turns out, that half-a-loaf strategy is worthless.
Children living in houses in which the city-owned section of lead pipe has been replaced have blood lead levels indistinguishable from those of children living in houses with intact lead pipes. And both groups of children run a significant risk of lead poisoning compared with children in houses with no lead pipes - even when the water system overall meets the federal standard of less than 15 parts per billion of lead.