EPA proposes new rules to get the lead out.
Ingested lead can do a lot of damage. And drinking water now accounts for about 20 percent of the typical U.S. resident's lead exposure, according to Environmental Protection Agency Administrator Lee M. Thomas. Last week, the EPA proposed new requirements aimed at lowering human exposure to the metal from U.S. drinking water. The regulations would affect an estimated 43,000 public water systems and lower exposures to lead in drinking water for about 138 million people.
Following a 60-day public comment period, EPA can enact the proposal or draft a revised one. Though some environmentalists says the current proposal fails to go far enough, they widely acknowledge its cost effectiveness. Besides reducing such risks as mental retardation, hearing loss and hypertension, the tougher regulations -- expected to cost about $207 million annually--should save $500 million annually in corrosion to U.S. plumbing, according to EPA estimates.
Most of the lead in U.S. drinking-water supplies comes from pipes (water mains to household plumbing) and the solder and brass fittings used to connect them. Though contact with water is all it takes to release lead from plumbing, corrosion of these pipes by acidic water greatly enhances their lead release.
Corrosity--and therefore lead leaching--increases with water temperature, notes William A. Sharpe, a water resources specialist at Pennsylvania State University in University Park. A preliminary sturdy by Sharpe and David R. DeWalle of eight homes in Pennsylvania -- where 85 percent of public water supplies are corrosive -- recorded more than a four-fold seasonal lead increase in one home's water. For instance, cold water leaving the tap during March and April was typical 44[deg.]F in one home -- and its lead concentrations consistently lower than 10 micrograms per liter ([muo]g/ l). By July, water from that same cold faucet was about 71[deg.]F and carried as much as 42]muo]g/l lead.
To limit excess lead leaching, EPA proposes a new corrosion control program. It would require public water suppliers to treat their water with alkaline additives when average lead levels at their consumers' taps are greater than 10 parts per billion (ppb), or if the water has a pH of less than 8. But EPA's Thomas concedes that even where they're needed, most corrosion controls will not likely be adopted quickly. A year or more of tap-waters surveys may be necessary to establish where problems exist. And the new rules permit water suppliers up to three years to study and develop treatment strategies tailored for their specific water-distribution system.
The proposal also would lower allowable levels of lead in drinking water to 5 ppb. Though the current limit is 50 ppb, the actual reduction would not be truly 10-fold, because the current limit is for water measured at the tap while the proposed standard would measure it leaving the treatment plant. Because most lead enters water after it leaves the treatment plant, this move to upstream measurement of the enforceable standard "is really not going to accomplish very much" in lowering public exposures, contends toxicologist Ellen Silbergeld of the Environmental Defense Fund in Washington, D.C.
Moreover, says Silbergeld, in the event corrosion control doesn't solve the tap-water-lead problem, EPA will not require water suppliers to do much more than initiate public information campaigns to teach consumers practices that minimize lead exposure -- such as "flushing" the pipes by letting water run for several minutes at the beginning of each day -- or suggest people replace their household plumbing.
Silbergeld thinks water suppliers should have to replace any of their leaded distribution pipes, and where the primary lead problem is in the home, the owner should be warned. She objects to EPA's suggestion that homeowners flush their pipes to lower lead exposure. This practice could "waste 3 billion gallons of water a day," she says.
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|Title Annotation:||new Environmental Protection Agency rules to lower lead levels in drinking water|
|Date:||Aug 20, 1988|
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