Jan. 12 (Bloomberg) -- Workers exposed to lead have more problems with memory and learning as they age, a study found.

Workers who were exposed to lead in the 1980s when they were in their 20s and 30s had lower cognitive functions 22 years later than workers who hadn’t been exposed to lead, research in the January issue of Neuropsychology showed. The journal is published by the American Psychological Association.

The findings add to other research that that shows lead can harm the brain, the researchers said. The metal can affect all organs and functions of the body and can lead to fatigue, impaired concentration, seizures, anemia and high blood pressure, according to the U.S. Centers for Disease Control and Prevention in Atlanta.

“Lead exposure may have long-lasting consequences for cognitive function and may make one more vulnerable to the cognitive effects of aging,” said study author Lisa Morrow, an associate professor of psychology at the University of Pittsburgh, in a Jan. 9 e-mail. “For anyone exposed to lead, the less exposure the better. We know lead has a detrimental effect on brain function and striving to lower exposure is optimal.”

The researchers looked at 83 lead-exposed workers and 51 non-exposed workers who were part of a 1982 study of occupational lead exposure. In the 1982 study, 288 lead-exposed workers and 181 non-exposed workers had their cognitive abilities assessed. Those exposed to lead worked at three lead battery plants in eastern Pennsylvania and were found to have above-normal blood lead levels.

In the new study, conducted between 2001 and 2004, researchers measured cumulative lead levels by using X-rays of the lower leg bone. Most lead that enters the body accumulates in the bones. The researchers also reassessed each worker’s cognitive performance.

Bone-Lead Levels

The researchers found that the amounts of lead in the bone predicted how workers performed on the cognitive tests. The association was strongest in those over age 55, Morrow said.

“When lead-exposed workers get to an age where cognition is expected to slow some, these workers had more decline compared to a control group, and this decline was significantly predicted by their bone-lead levels,” she said.

Lead, a toxic metal, also can accumulate in parts of the brain and can lead to nerve cell death, Morrow said.

The U.S. Occupational Safety and Health Administration requires workers who have blood lead levels of more than 40 micrograms per deciliter of blood to have an annual medical evaluation. Those workers whose levels exceed 50 micrograms per deciliter must be removed from the workplace.

The study was funded by the National Institutes of Health.

To contact the reporter on this story: Nicole Ostrow in New York at nostrow1@bloomberg.net.

Last Updated: January 12, 2009 06:45 EST