Environmental Factor, January 2005, National Institute of Environmental Health Sciences
NIEHS-Funded Study Links Lead Exposure with Increased Risk of Cataracts
Researchers at the Harvard School of Public Health and Brigham and Women's Hospital concluded that lifetime lead exposure may increase the risk of developing cataracts.
The nine-year study, which NIEHS funded, looked at lead levels in the tibia, the larger of two leg bones below the knee, and in the kneecaps of men in the Boston area. Men with high lead levels in the tibia had a two and a half times greater risk of developing cataract, the leading cause of blindness and visual impairment, the study found.
Blood lead levels reflect recent exposures, while bone levels reflect long-term exposure, researchers said.
“Given the strong association between tibia lead and cataract in men, we estimate that lead exposure plays a significant role in approximately 42 percent of all cataracts in this population,” said Debra Schaumberg, assistant professor of medicine and ophthalmology at Harvard and lead author of the study. She said cataracts develop as a result of cumulative injury to the crystalline lens of the eye. As lead enters the lens, it gradually injures certain proteins in the epithelial cells, eventually forming a cataract.
Harvard researchers are among the first to use bone lead in studying the effect of lifetime lead exposure on disease risk. The study results appeared in the Dec. 8 issue of the Journal of the American Medical Association. The study also looks at the effects of lead on hypertension, kidney impairment and cognitive functioning.