Long-term exposure to high levels of lead seems to triple the risk of developing cataracts, according to a report in the Journal of the American Medical Association.

Previous studies have identified lead in the lenses of people with cataracts, but it was unclear if accumulated lead exposure was a risk factor for the condition.

To investigate, Dr. Debra A. Schaumberg, from Brigham and Women’s Hospital in Boston, and colleagues analyzed lead levels and eye examination data for 642 older men who participated in the Normative Aging Study. The subjects were at least 60 years of age.

Cataracts were identified in 122 men, the researchers report. After accounting for cigarette smoking, diabetes, blood lead levels, and vitamin intake, people with the highest levels of lead in their shinbone - a test for long-term exposure - were 3.2-times more likely to have cataracts than those with the lowest levels.

Cataract risk also rose as lead levels in the kneecap climbed, but the association was not as strong as that seen with lead in the shinbone. In contrast, no association was seen with blood lead levels, which only reflect short-term lead exposure.

“These are, to our knowledge, the first data suggesting that accumulated lead exposure, such as that commonly experienced by adults in the United States, may be an important risk factor for cataract,” the authors state. “This research suggests that reduction of lead exposure could help decrease the global burden of cataract.”

SOURCE: Journal of the American Medical Association, December 8, 2004.