In critiquing a common safety standard for brass used in plumbing,researchers have found the regimen may be flawed. As a result, theysay, some of the lead that crept into tap water in Washington, D.C.,and other metropolitan areas may be traceable to household fixtures,valves and other components and not just pipes and systems further fromthe home.
The new study looked at the American National StandardsInstitute/National Sanitation Foundation 61 Section 8 standard--aprotocol consisting of specific methods and test-water formulas thatgovernments and industries have relied upon to ensure safe plumbingsince 1988.
"As a result of problems identified with the test protocol,some products passing National Sanitation Foundation Section 8 may havea greater capacity to leach lead into water than we believed," saidMarc Edwards of Virginia Tech, who is one of the study leaders.
Edwards, Abhijeet Dudi and Nestor Murray, all at Virginia Tech,and Michael Schock, of the Environmental Protection Agency (EPA)National Risk Management Research Laboratory, report their findings inthe Aug. 4 issue of the Journal of the American Waterworks Association.
Edwards, Dudi and Murray are members of a multidisciplinaryteam supported by a National Science Foundation Materials Use: Science,Engineering and Society (MUSES) award.
The researchers tested identical brass devices purchased from alocal hardware store by subjecting the pieces to the Section 8 protocoland to modifications they made to the protocol. They also applied thesame tests to a simulated plumbing device made of solid lead.
The results: The Section 8 water samples reacted less, or wereless "aggressive," with lead in the plumbing than designers of thestandard had intended. The researchers found other problems thatstemmed from calculations that underlie some of the test results.Normalization factors allow evaluators to estimate actual leadconcentrations at the tap, but they are affected by device size.Because of normalization and the non-aggressive waters, the small,simulated device made of pure lead pipe passed the Section 8 leachingtest.
The scientists began to scrutinize the Section 8 methods afterlearning that one of the test solutions contains high concentrations oforthophosphate to buffer the water's pH. Water utilities useorthophosphate actually to inhibit lead leaching. So, test solutionscontaining such leaching inhibitors could not react adequately withplumbing and would produce a flawed reading.
"It's analogous to an automobile crash test using a wall of pillows," Edwards said.
Becauselead softens alloys, it is an important component in many plumbingmetals. Without adding small quantities of lead, manufacturers couldnot craft intricate shapes necessary for modern devices. Under certainchemical conditions, such as high acidity or low amounts of carbondissolved from minerals, the devices can leach significant amounts ofthat lead into water.
The problem is complex because treatments necessary to treat onewater-quality problem, such as bacteria, can have unintendedconsequences, such as lead leaching.
In the 1986 Safe Drinking Water Act as amended in 1996 (USEPA, 2000),Congress explicitly banned new devices containing pure lead pipe,leaded solders, and brass with more than 8 percent lead content.However, these materials remain installed in older homes.
At the time of the legislation, there were no alternatives forleaded brass, and experts believed it was not feasible to reduce leadcontent in devices to that in pipes and solder.
Some components are labeled lead-free, even if they contain 7.99percent lead. Despite such labeling, all brass products that containlead must pass the Section 8 performance-testing standard.
Recently, legislators have proposed updated laws to allow for modernbrass alloys--some containing as little as 0.02 percent lead or less byweight--which could reduce lead leaching considerably .
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