Even low lead levels harmful

Even low levels of lead found in the blood during early childhood can adversely affect how a child's cardiovascular system responds to stress and could possibly lead to high blood pressure later in life, new research hints.

In the study, researchers found that very low blood lead levels -- well below the 10 micrograms per deciliter threshold for harmful effects set by the U.S. Centers for Disease Control -- was associated with an increase in vascular resistance when the children worked on a stressful computer task.

Vascular resistance is a measure of tension within the blood vessels. Increased vascular resistance may cause high blood pressure if it continues over time.

The study of 140 healthy adolescents also found that lead exposure was associated with a drop in levels of the blood pressure-regulating hormone aldosterone.

Dr. James A. MacKenzie of the State University of New York at Oswego presented the findings at the American Physiological Society annual meeting in New Orleans.

It's noteworthy, MacKenzie told Reuters Health, that adverse cardiovascular effects in response to stress were seen at very low lead exposures.

All of the children had blood lead levels well below the 10 micrograms per deciliter that the CDC defines as a "level of concern," he said. The highest lead level for the children in this study was just 3.8 micrograms per deciliter.

MacKenzie cautioned, however, that these are "preliminary studies" and much more work needs to be done. However, "we are seeing very interesting findings," he said.

(Megan Rauscher/Reuters Health – April 2009)