Lead risk worst for fetuses, children

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Pregnant women and children ages 6 and younger are the only populations that have to fear excess lead in the District's drinking water, health specialists at the local and national levels say.

"Only the most at-risk populations can be affected by excessive lead levels [in drinking water]. There is no medical literature on ill effects on folk from 7 years [old] onward," unless they are pregnant women, said Dr. Thomas Calhoun, medical director of the D.C. Health Department's Emergency Health and Medical Services.

Dr. John Rosen, professor of pediatrics at Children's Montefiore Hospital in New York, who heads the hospital's lead program, said, "The most susceptible populations would be pregnant women and young children, ages 1 to 6, because of the rapid development of the brain in utero and during a child's first six years."

For fetuses and young children, Dr. Rosen said, the damage caused by excess lead tends to center on the brain and is "irreversible."

High levels of lead have been detected in the District's drinking water, and the D.C. Water and Sewer Authority has begun a multimillion-dollar program to replace lead-lined pipes in the city.

Studies suggest that even low lead levels can cause reduced intelligence, decreased growth, impaired neurobehavioral development and impaired hearing, according to the federal Centers for Disease Control and Prevention (CDC).

In 1991, the CDC said lead levels in the blood should not exceed 10 micrograms per deciliter. "But there are studies dating back from 1994 to April 2003 that indicate that going from a blood lead [reading] of 1 microgram per deciliter to 9 micrograms per deciliter results in an average deficit of 7.4 IQ points," Dr. Rosen said.

"There's still a lot of controversy about those findings," said Henry Abadin, an environmental scientist with the Agency for Toxic Substances and Disease Registry, which is affiliated with the CDC.

Nevertheless, Mr. Abadin said a blood lead level of 15 to 20 micrograms per deciliter is enough to impair production of hemoglobin, the iron-containing pigment of red blood cells. Hemoglobin carries oxygen from the lungs to the tissues.

"We know what lead does at high levels, and there is some evidence it affects I.Q. scores" at low levels, he added.

"We have not been able to find any thresholds below which there are no adverse effects," Mary Jean Brown, chief of the CDC's lead-poisoning prevention branch, told the Houston Post.

Repeated attempts yesterday to find how much lead-tainted water someone would have to drink to suffer harm were unsuccessful.

Since the 1980s, the U.S. Environmental Protection Agency has said lead levels in water should not exceed 15 parts per billion. But the lead level in thousands of D.C. homes has tested at 50 parts of billion, with some at 300 parts per billion.

Dr. Herbert L. Needleman, a professor of pediatrics and psychiatry at the University of Pittsburgh who has studied the effects of lead on children's intelligence, did some calculations yesterday. He said through an aide that if the lead level in water is 15 parts per billion, just "three 8-ounce glasses of water per day would be over the acceptable amount."

In the District, Dr. Calhoun said the concentration of lead in the water of a single home will fluctuate "with the number of flushes."

As for the high blood lead levels found to date in 11 D.C. children and one adult, he said they "don't equate with clinical problems."

Noting that one child was found with a blood lead level of 23 micrograms per deciliter, Dr. Calhoun said that figure has since been reduced to 16 micrograms per deciliter.

"We're still recommending that people filter the water, since filtering will extract 97 [percent] to 98 percent of lead from the water," he said.