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Lead in utero: low-level danger.

Lead in utero: Low-level danger

Exposure to small amounts of leadbefore birth, even at levels considered safe for children, appears to slow important aspects of mental development in the first two years of life, according to a study described in the April 23 NEW ENGLAND JOURNAL OF MEDICINE. The project will follow lead-exposed children beyond 2 years of age to see if these effects persist, say David Bellinger of Children's Hospital in Boston and his colleagues.

In a previous study of 300 low-incomefamilies in inner-city Cincinnati, pregnant women exposed to low levels of lead had an increased chance of bearing children with low birthweight and somewhat slowed neurological development (SN: 9/13/86, p.164).

The Boston researchers studied 249infants from middle- and upper-income families. They determined prenatal lead exposure by taking samples of umbilicalcord blood at birth. Children were divided into three groups: those with less than 3 micrograms of lead per deciliter in their blood, those with 6 to 7 micrograms per deciliter and those with 10 to 25 micrograms per deciliter. Blood lead levels higher than 25 micrograms per deciliter are deemed unacceptable for young children by the federal Centers for Disease Control.

For two years after birth, the babieswere periodically given a standard mental development test that includes measures of simple problem-solving, perception, memory, learning and coordination. The group of children with the highest lead levels consistently had the poorest scores. By the age of 2, those with the highest exposure had a markedly lower average score on the development test than those in the other two groups. Infants with high lead levels still performed slightly above the population average.

Since only socially advantaged familieswere studied, the observed link between lead and mental development may be a conservative estimate, note the researchers. Lead's adverse effects can be amplified in an impoverished environment, they say, by factors such as poor nutrition.

Leading sources of lead exposure, saythe researchers, are automobile exhaust and lead-based paints. They add that studies based on umbilical-cord blood samples indicate that more than one-fourth of the newborns in urban areas have lead levels of more than 10 micrograms per deciliter.

If their finding is repeated in furtherstudies, the investigators say that the current federal standard for acceptable blood levels in young children should be lowered for fetuses.
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Title Annotation:dangers of exposure to small amounts of lead before birth
Author:Bower, Bruce
Publication:Science News
Date:May 2, 1987
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