No Safe Level of Lead, Study Shows

Houston Chronicle April 17, 2003

‘NO SAFE’ LEVEL OF LEAD, STUDY SHOWS

By THOMAS MAUGH Los Angeles Times

Lead levels widely believed to be safe in “ There is a message for parents in here that children produce a severe impact on goes beyond whatever government policy intellectual development, researchers report. recommendations should be,” Canfield said. Blood levels of lead below current federal Just as parents should protect their children and international guidelines of 10 micrograms from the effects of smoking and alcohol use, per deciliter produce a surprisingly large 7.4- they “should be aware of sources of lead in point drop in IQ, a U.S. team reports in their environment and, most importantly, today’s New England Journal of Medicine. should try to engage in some type of cleanup or abatement so the child never comes in Researchers estimate that one in every 50 contact with lead.” U.S. children has lead levels above that guideline and that one in every 10 has levels Even less exposure of 5 micrograms/deciliter or above - well can lower kid’s IQ within the dangerous range.

“People have been asking, ‘How low (a lead In a separate paper in the journal, researchers concentration) is low enough?”’ said Dr. from the Environmental Protection Agency Richard Canfield of Cornell University, one also found that low levels of lead delay of the leaders of the study. “The fact is, in puberty for several months in young girls, our study, we found no evidence for a safe especially blacks and Hispanics. level. There is no safe level of exposure.” Although delaying puberty is not necessarily The findings “reflect the growing opinion that harmful, the findings suggest that lead is low levels of lead are more toxic than we interfering with critical hormonal processes thought,” said Dr. Herbert A. Needleman, a during development. prominent lead researcher who was not involved in this study. “When we took the “ That fits in with the increased interest in lead out of gasoline that left one remaining general with the idea that environmental big source, old houses.” chemicals can be endocrine disruptors,” said Dr. David Bellinger of Harvard Medical An estimated 38 million houses built before School. “Lead has not been considered as 1950 still have lead-based paints on their prominently as other chemicals. This suggests walls. that we ought to be looking at it more closely.” Lead is a potent toxin that adversely affects In 1976, when lead was removed from organs throughout the body. Recent studies gasoline, the average lead level in children have shown that higher levels not only reduce was about 15 mcg/dl. Today, the average is intelligence and slow development, but also about 3. “But that’s still 10 to 100 times can lead to behavioral problems, juvenile higher than the level in pre-industrial delinquency and even criminality. As these humans,” said Dr. Bruce Lanphear of the studies have appeared, guidelines for Cincinnati Children’s Hospital Medical exposure have continued to be lowered. Center, another study leader. “Three mcg/dl is low by current standards, but from an In the 1960s, doctors diagnosed lead evolutionary perspective, it is quite high.” poisoning if blood levels were above 60 micrograms per deciliter (mcg/dl), high Canfleld and Lanphear’s team studied 172 enough to cause abdominal spasms, kidney children in the Rochester, N.Y., area, injury and severe brain damage. measuring blood lead levels at ages 6, 12, 18, 24, 36, 48 and 60 months. The children were tested for IQ at both 3 and 5 years of age. After studies in the 1980s and 1990s revealed that lower levels still damaged children’s They found that a rise in lead levels from 1 ability to think, concentrate and hear, the mcg/dl to 10 was associated with a 7.4-point Centers for Disease Control and Prevention drop in IQ. An increase in lead levels from continued to reduce the allowable level - to 10 to 30 mcg/dl was associated with an 30 mcg/dl in 1975, 25 mcg/dl in 1985, and to additional drop of only about two to three IQ the current level of 10 mcg/dl in 1991. points, in line with previous studies.