SUNDAY, DECEMBER 12, 2010
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C5 D.C. water study sharpens understanding of lead threat lead from C1
Health, who serves on a working group of the federal government’s Advisory Committee on Child- hood Lead Poisoning Prevention. “We’re spreading the word
about it [the report]. It went out to our members as a hot news item,” saidSteveVia,headof regu- latory affairs for the American Water Works Association, whose membershipincludes 4,100water systems serving about 80 percent of theU.S. population.
‘A really big deal’ The source of the problemisno
secret. It is lead pipes, some dat- ing fromthe 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 thepipe,municipalwater systems own — and control — only the sectionfromthemaintothehom- eowner’s property line. If a city’s water violates federal lead stan- dards, the first thing the water systemmust do is treat the water to make it less corrosive and less likely toleachleadfrompipes and solder. If that doesn’t work, the Environmental Protection Agen- cy orders cities to replace the public part of lead service lines. But as it turns out, that half-a-
loaf strategy isworthless. Children living in houses in
which the city-owned section of lead pipe has been replaced have blood lead levels indistinguish- able fromthose of children living in houses with intact lead pipes. Andbothgroups of childrenruna significant risk of lead poisoning comparedwithchildreninhouses with no lead pipes — even when the water system overall meets the federal standard of less than 15 parts per billion of lead. Curiously, the EPA has no idea
how many water utilities in the United States are doing “partial lead service line replacement” and might like to know that, in Washington at least, that proce- dure made no difference to chil- dren’s health. States enforce the federal lead
standard. Only recently has the EPA asked them to report the number of water utilities doing partial-pipe replacement. Of the 354 water systems currently in violation, the agency knows of 11 using that laborious and expen- sive strategy to lower the lead in their water. There could bemany more.
IntheCDCstudy, five scientists
analyzed routine blood lead tests done on 64,000 District children from 1998 through 2006. They correlated the results with the child’s age, whether the child’s home was served by a lead pipe and the age of
thehouse.That last variable is crucial because a child’s biggest exposure to lead comes fromdusty residues of lead paint on floors and walls and in yard dirt. Old houses are much more likely to have lead paint. What they found was trou-
bling. About 16 percent of children
sampled during the nine-year pe- riod had blood lead levels from five to ninemicrograms per deci- liter. Slightlymore than 3 percent had levels exceeding 10 micro- grams, the federal government’s current definition of “elevated” blood lead. (CDC has lowered the cutoff for “elevated” blood lead four times since the 1970s, and many experts consider the cur- rent threshold too high). The large number of children
at risk of lead-induced health problems — 19 percent of the nearly 64,000 children—was just one of the findings. The study, published in the
journal Environmental Research, also found that children living in houseswith lead pipeswere three times as likely to have elevated blood lead as children in houses without lead pipes. The youngest children were at
the highest risk. Infants and tod- dlers younger than 16months old (many drinking formula mixed withwater), had a fourfold risk of having blood lead over 10 micro- grams. That was true in 1998, 1999 and the first 10 months of 2000, a period inwhichWashing- ton’s lead-in-water level was be- low 15 parts per billion. Children in houses where lead pipe had been partially replaced were no better off than those in houses whose lead pipes had not been touched. To the researchers’ surprise,
the conclusions held even after they tookthe age of a child’shome into account. “I was expecting that any ex-
cess riskmight have disappeared once we controlled for the age of housing — in other words that sources of lead other than water were responsible,” said Thomas Sinks, a CDC epidemiologist and one of the authors of the study. “What we found is that there remainsacontributionfromlead- ed pipes that continues despite compliance” with government
lead-in-water standards. Other experts were impressed
by the results. “This is a really big deal,” said
Marc Edwards, a Virginia Tech engineer who has warned of the hazards of the District’swater for years. “Meeting the EPA lead-in- water standard is not sufficient. Just because you’re meeting the ‘action level’ doesn’t mean that your child is not threatened.” “This is very different from
what CDC was telling us in the past,” saidLynnGoldman,deanof the school of public health at George Washington University and an expert on lead poisoning. “What is not clear to me is what the CDC actually recommends on the basis of this.”
What’s safe? How big is the threat from
small elevations of blood lead the children experienced? Research over the past two decades sug- gests that the effects are small but measurable, and all negative. A study published in 2007 that
looked at 534 children, ages 6 to 10, in Boston and rural Maine found that “children with blood lead levels of 5-10 . . . had signifi- cantly lower scores on IQ, achievement, attention, and working memory than did chil- dren . . . who had levels of 1-2.” A working group of experts assem- bled by CDC in 2004 examined many studies and concluded that there are “at least in part, causal adverse impacts of lead on chil- dren’s cognitive function at blood lead levels less than 10.” The current lead levels in the
District’s water stem from deci- sions made over the past decade, usuallywiththegoalof improving public health. The water District residents
drink is collected, treated and sold to the city by theWashington Aqueduct, a federal entity run by
theU.S.ArmyCorps ofEngineers. To disinfect its water, the Aque- duct used to employ chlorine, a chemical that canreactwithcom- pounds in water and produce by- products that cause cancer. To avoid that problem, many
cities—includingWashington in 2000 — switched to a “safer” chemical, chloramine. But it turns out that chlorine suppress- es corrosion of pipes, including lead ones, and chloramine does not. The leaching of lead from pipes and solder increased after the city switched disinfectants, and eventually the lead concen- tration exceeded 15 parts per bil- lion.
‘Good intentions’ When the EPA started regulat-
ing lead in tap water in the early 1990s, one of its enforcement tools was a requirement that a water systemin violation replace lead pipes in total. But several organizations, including the American Water Works Associa- tion, sued, saying that to comply, government would have to make improvements on private proper- ty. In 2000, a court agreed. After the EPA revised its rules
to require only replacement of publicly owned lead pipe, several studies showed that partial re- placement lowered the amount of lead in water. But there were no studies showing that it lowered the amount of lead in children. Many experts, in fact, doubted
that partial replacement would
achievemuch.Not onlywere they right, it also turns out that the strategy can temporarily make things worse. Removing half the pipe can jar loose protective de- posits inside the remaining sec- tion. Lead in the water can spike after the work is done and take months to return to normal. That’s now recognized as a seri- ous enoughproblemthat theCDC put out a warning about it this year. On June 17, 2004, the District’s
water authority agreed with EPA to replace a specified number of lead service lines per year. Thewater agency offered prop-
erty owners a discount price of $100 per foot if they agreed to replacetheirpartof
thepipes.The average length of the pipe on city property was 30 feet, and on pri- vate property, 20 feet. Through September 2009, the District re- placed its portion of 17,654 lead service lines, but the privately owned section was replaced in only 2,832 of those lines, 16 per- cent of the total. After four years and $80 mil-
lion, the lead in the District’s water returned to a level less than the 15 parts-per-billion limit. But pipe replacement probably had very little to dowith it. That’s because in June 2004
theWashingtonAqueduct started adding a chemical called or- thophosphate to thewater. It cre- ates a film on the inside of pipes, reducing corrosion and the leach- ing of lead and other metals. By January 2006, the orthophos- phate treatment had brought the city into compliance. The latest readingthis yearwas
7 parts per billion. The sampling is intentionally done in high-risk houses. Out of 100 houses with
fullorpartial leadservicelines,90 percentmusthavewater leadcon- centrations below 15 parts per billion for the city to pass. Once the District came into
compliance, it no longer had to followtheEPA’s order to replace a certain number of lead service lines each year. The accelerated program end-
ed in September 2008, although the utility continues to replace lead pipes when it encounters them in the course of other work or if a customerdecides to replace the private portion. “Weneverwantedtodopartial
lead replacements in the first place,” said D.C. Water’s general manager, George Hawkins. “It was a requirement, and at the time, it was thought to be a good
idea.Thereweregoodintentions.” At the moment, 13,395 lead
service lines remain on public property, he said. There are also 17,622 lines
whose material is not known, al- though experience suggests that somewhat fewer than half are made of lead. By rough estimate, the city
would need to replace all or part of 25,000 service lines, at a cost of well over $200 million, to make its water system as lead-free as possible. It would also take a change in law to compel home- owners to change their pipes or to fully reimburse them.
Theway forward Other cities have taken on such
herculean tasks. Madison, Wis., with 230,000
people and 65,000 households, is nearing the end of a 10-year proj- ect to replace all of its lead service lines. It is using a twin strategy of inducement and punishment. The city rebates to homeowners half the cost of the work, up to a maximum of $1,000. Those who refuse face a fine so high that just about none have refused, said TomHeikkinen, generalmanager of the utility. Saskatoon, Saskatchewan,
which is about the size of Madi- son, is replacing all the lines and charging homeowners 40 percent of the cost of the work, up to $2,000, and putting it on their tax bills. D.C. Water is addressing the problem case-by-case, offering free testing to residents and pro- vidingwater filters tohousesafter all or part of a lead service line is replaced. “We are not currently contem-
plating replacing all of the lead service lines intheDistrict,public and private,”Hawkins said. A spokesman for the EPA said
the agency still requires partial- pipe replacement when a water system cannot comply by other means. But, he said, “we are tak- ing very seriously this new CDC study. It is eye-opening andshows that we need to continue assess- ing howeffective this strategy is.”
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