Shoring up
shocking levels of lead in Washington's tap water have prompted us lawmakers to introduce a bill to amend the Safe Drinking Water Act (sdwa). The new bill, called Lead-free Drinking Water Act of 2004, proposes several changes, including increasing funding to clean up tap water.
One of the main recommendations is that Congress should redefine "lead free' in sdwa as no more than 0.1-0.25 per cent. At present, "lead free' refers to less than 0.2 per cent lead in solders and flux, and less than 8 per cent lead in pipes, pipe fittings and well pumps.
As many as 4,075 houses in the country's capital have exceeded the us Environmental Protection Agency (epa) lead limits of 15 parts per billion (ppb). Of these, 2,287 houses had lead levels above 50 ppb, 157 had lead levels more than 300 ppb and 11 had lead levels more than 500 ppb. These houses are spread throughout the city.
The lead comes mainly from the district's 130,000 water service lines for residential customers. About 23,000 of these are made of lead, while the rest are made of copper. The lead pipes mostly serve older homes. According to officials of Washington dc's Water and Sewer Authority (wasa), this problem is confined to homes built in the early 1900s or during 1930s and the subsequent decade of World War II, when copper shortages forced plumbers to use lead pipes.
But there is another theory. wasa gets its water from the Washington Aqueduct, the capital's first public water system. The water here has for long been treated with chlorine to kill bacteria. The chlorine combined with organic material in pipes and created new harmful chemicals. Four years ago, scientists added ammonia to balance the chlorine, creating a compound named chloramine. It is believed that this compound corrodes lead pipes faster.
Some experts aver that extraordinary amounts of water need to be consumed for its lead content to pose a risk. John F Rosen, a paediatrics professor and the chief of comprehensive lead programme at the Montefiore Medical Center, Albert Einstein College of Medicine, says: "A child will have to drink an awful lot of water for it to have a measurable effect.' But Mary Jean Brown, chief, lead poisoning branch, Centers for Disease Control's National Environmental Health Center, disagrees: "For small children, water could be a significant source of exposure.'
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