The research, which was published in the May issue of Neurology a scientific journal of the American Academy of Neurology examined 532 former employees of a chemical manufacturing plant. The employees worked there an average of 8 years each.
After measuring the amounts of lead accumulated in the employees' bones, researchers found that 36 percent of them had white matter lesions, or small areas of damage in the brain tissue. According to the study, those with the highest levels of lead were more than twice as likely to have brain damage as those with lower lead levels. The study also found that those with the highest levels of lead had brain volumes 1.1 percent smaller than those with the lowest lead levels.
According to Walter Steward, Ph.D., of the Center for Health Research of the Geisinger Health System in Pennsylvania and author of the study, the effect of lead exposure was equivalent to what would be expected for 5 years of aging. He also said the results confirm earlier findings in the same population that people with occupational lead exposure experience declines in their thinking and memory skills years after being exposed to the toxic metal.
"The effect of lead on the brain is progressive," Stewart said. "These effects are the result of persistent changes in the structure of the brain, not short-term changes in the brain's neurochemistry."