In response to this need, the NIEHS conducted a clinical trial to test Succimer in 800 children with low lead concentrations in their blood to determine if oral chelation reduces or prevents lead-induced developmental delay.
The NIEHS continues to perform and support research on the effect of lead on children's health. This research has important implications for other environmental hazards as scientists believe that lead may be used as a model of how other substances can harm a fetus or developing child and adolescent, even at relatively low levels of exposure.
PCBs and Intelligence
PCBs, or polychlorinated biphenyls, were commonly used in electric transformers, paper recycling, and other commercial processes until they were shown to impair intelligence. Partly as the result of the NIEHS studies, PCBs have been banned from use; however, they are stable, persistent compounds that remain widespread in the environment. PCBs are fat soluble, meaning they concentrate in the fat of animals, and ultimately in the people who eat these animals.
NIEHS studies have shown that PCBs can cross the placenta and expose the developing fetus, and that nursing mothers can transfer PCBs to their infants through breast milk. Fetal exposure translates into lower IQ, poor reading comprehension, memory problems and difficulty in concentration. These dangers motivated the FDA and state advisories warn to against women of child-bearing age and children under 15 to avoid fish caught in contaminated waters.
Scientists with the NIEHS studied 117 children born to women poisoned by PCBs through food contamination in Taiwan in 1979. The PCBs were heat-degraded, causing them to partially convert to polychlorinated dibenzofurans (PCDFs). The exposed children presented carious (decaying) teeth, poor nail formation, and short stature, and were more likely to have behavioral problems, hyperactivity, and persistent developmental delays averaging 5 to 8 points on standard IQ scales. In addition, the developmental delays were as severe in children born up to six years after the initial exposure as those born in 1979, demonstrating the persistence of these chemicals in the body.
Childhood Asthma and Other Lung Problems
Asthma affects up to 20 million Americans and its prevalence and severity appear to be increasing among children, particularly Hispanics of Puerto Rican origin and African Americans.
Studies at Harvard University's Kresge Center for Environmental Health have shown a strong and consistent relationship between elevated indoor concentrations of oxides of nitrogen and lower respiratory tract symptoms; and suggest that exposure to sulfur dioxide, particulate matter, and acid aerosols in urban (outdoor) air is associated with bronchitis in children. A related study is assessing the degree of risk of minority and/or disadvantaged children from such things as air contaminants from kerosene heaters.
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