In pregnant women, even small amounts of lead in the blood may cause significantly higher blood pressure, new research suggests.
The study of 285 pregnant women found that about one in four had a lead level higher than about 1 microgram per decilitre (1 mcg/dL) of umbilical cord blood.
That's significantly lower than the safety thresholds set by the US Centers for Disease Control and Prevention, which recommends taking action to reduce lead exposure when pregnant women or children have a blood lead level of 5 mcg/dL.
Even so, women in the study with lead levels greater than 1 mcg/dL had higher systolic and diastolic blood pressure readings than those with lower lead levels. The average increase was 6.9 mm Hg and 4.4 mm Hg, respectively.
Pregnant women sensitive to toxicity
Though further research is needed, the findings suggest that pregnant women may be as sensitive to lead toxicity as young children, said the researchers. Prolonged high blood pressure during pregnancy can lead to complications such as pre-eclampsia or eclampsia, potentially deadly seizures that also can increase a woman's future risk of heart attack.
"We didn't expect to see effects at such low levels of lead exposure, but in fact we found a strong effect," said Dr Lynn Goldman, dean of the George Washington University School of Public Health and Health Services.
The study did not find an association, however, between lead exposure and pregnancy-induced hypertension or pre-eclampsia.
The study was published in the journal Environmental Health Perspectives.
Lowering the limit on workplace exposure to lead may be a good starting point in protecting pregnant women, Goldman suggested.
"The occupational standard right now is a level of 40 mcg/dL, and we see blood pressure changes at a level of 2 [mcg/dL]," she said.
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