In Utero Exposure to Lead Reduces Children’s IQ

Mitch Kennedy, ND

Many epidemiologic studies have shown the relationship between children’s exposure to lead during developing years and the detrimental effects on neurologic development. A new study done in Mexico looked at IQ level of children exposed to lead in utero, and followed their development up to age 10. One hundred and seventy children had a mean blood lead (BPb) of 8 ug/ml in utero (range of 1-33 ug/ml). The largest declines in IQ were seen when exposures occurred during the third trimester.

Lead exposure around 28 weeks gestation is a critical period for later child intellectual development, with lasting and possibly permanent effects. There was no evidence of a threshold; the strongest lead effects on IQ occurred within the first few micrograms of BPb.

The take-home message: the current CDC action limits for blood lead levels in children do not protect against lead-associated child IQ decreases when applied to pregnant women.

Source: Schnaas L et al: Reduced intellectual development in children with prenatal lead exposure, Environ Health Perspect 114:791-7, 2006.

Mitch Kennedy, ND has a family practice in Avon, CT, and is the first ND with clinical privileges at the University of Connecticut, a teaching hospital. Before graduation from Southwest College, Kennedy earned an international reputation as a leader in pollution prevention, showing industries around the world how preventing pollution saves money.

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