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PREVENTING PIPE CORROSION IS THE KEYTO LOWERING LEAD LEVELS IN DRINKING WATER

 VALLEY FORGE, Pa., Sept. 14 /PRNewswire/ -- Changes in the Safe Drinking Water Act proposed by the Clinton administration would strengthen enforcement of regulations covering lead in drinking water.
 The U.S. Environmental Protection Agency (EPA) intends to crack down on the use of lead in plumbing pipes, the main source of lead contamination in drinking water.
 More than 30 million people in the United States have excessive levels of lead in their drinking water at home, the agency recently found, and the agency has ordered the water systems serving them to take steps to reduce lead levels. But the problems of lead contamination of drinking water is complex and widespread, and reducing levels can be a tricky process.
 EPA rules regarding lead in drinking water focus on preventing pipes from corroding, rather than removing lead from the pipes or replacing the pipes themselves, as the most cost-effective solution to the problem of lead contamination. The current standard calls for 90 percent of the homes sampled to have lead levels of less than 15 parts per billion (ppb) at the tap.
 Pat Delaney, project manager at PQ Corporation, a manufacturer of industrial chemicals used in water treatment, said, "Because the type of water in a community is such a critical factor, the type of solution that works in one area will not work as well in another. And it may be that several products together provide the best answer. Picking the right combination depends on the water chemistry."
 According to Delaney, lead contamination occurs in most cases when the water passes from the utility's distribution system into a customer's home. "Water utilities argue correctly that they don't put lead in the water," he said. "In 99 percent of the cases, the lead levels are well below the EPA standards when the utility releases its water. However, if the water is very acidic (hard) or very alkaline (soft), it can cause corrosion of soldered copper pipe or plumbing fixtures in the home, allowing the lead to enter the drinking water.
 "Before, when people had corrosion problems, they were often manifested as rust-colored or greenish water," added Delaney. "In other words, there was a heavy concentration of copper or iron that was visible. When water authorities received complaints, they solved corrosion problems on a case-by-case basis. But lead corrosion usually is not visible."
 Serious health problems can result from the lead contamination. In children, lead interferes with brain development and physical development and can cause low birth weight or premature birth. In adults, it can increase blood pressure and damage hearing, among other effects.
 Delaney said the EPA and other federal agencies "have redefined a water authority's responsibility as one of supplying to customers' homes water that is not corrosive." The agency has recommended several ways to treat water at its source so that it doesn't pick up lead on its way to the customer's tap. They include:
 -- Increasing the pH above 7 to make the water less corrosive. This can be done by adding soluble silicates, such as sodium silicate, lime, caustic soda, soda ash, etc. These raise the pH, thus reducing the rate at which lead and other metals will dissolve. Delaney said silicates have been used for more than 70 years to control lead.
 -- Increasing the hardness of the water so that it develops a scale or coating, which prevents the water from affecting the pipes.
 -- Using an inhibitor, either silica-based or phosphate-based, which reacts with the pipe's interior surface to form a film that acts as a barrier to corrosion. Silica-based inhibitors can also raise pH to make water less corrosive. However, Delaney emphasized that since phosphates are nutrients for algae, they are less suitable for use in communities that store treated water in an open reservoir, a common practice in many states.
 According to Delaney, a number of water utilities around the country have been able to bring lead levels into compliance by using silicates alone or by combining them with other inorganic chemicals. And under certain conditions, silicates are as cost-effective as phosphates. For example, in New England and other regions with very acidic water, raw water must first be treated with caustic soda or soda ash to raise the pH to the mid-seven range before phosphates would work. Then adding additional chemicals increases treatment costs. But silicates will raise pH and inhibit corrosion.
 In addition, Delaney said silicates treatments are less labor intensive and don't require special handling, as soda ash and lime do. But Delaney again emphasized that success is very site-specific and each water system must be evaluated independently.
 The PQ Corporation, headquartered near Philadelphia in Valley Forge, specializes in the manufacture of inorganic industrial chemicals and glass beads. PQ's soluble silicates and their derivatives make significant contributions in a variety of products and industries, including detergents, construction, transportation, pulp and paper, food and beverages, and waste management.
 /delval/
 -0- 9/14/93
 /CONTACT: Dorie Owen of PQ Corporation, 215-293-7330, or Neil Gussman of Godfrey Advertising, 717-393-3831, for PQ Corporation/


CO: PQ Corporation ST: Pennsylvania IN: ENV SU:

JM-MK -- PH011 -- 1721 09/14/93 11:12 EDT
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Date:Sep 14, 1993
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