Risks From Occupational Lead Exposure Last A Lifetime, Pitt Study Finds - Combination Of Age And Early Exposure To Lead Significantly Increase Risk

Main Category: Seniors / Aging
Also Included In: Blood / Hematology
Article Date: 26 May 2008 - 4:00 PDT

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Older workers with past occupational exposure to lead face increased risk for recirculation of lead into their bloodstreams later in life, according to a study by University of Pittsburgh researchers published in the current issue of Archives of Environmental and Occupational Health.

"The neurotoxic effects of lead have been documented for over a century," noted Lisa A. Morrow, Ph.D., lead author and associate professor of psychiatry and psychology at the Western Psychiatric Institute and Clinic of UPMC. "Our study found that even workers with no current workplace exposure to lead - but who have had considerable past exposure - show increasing levels of lead in their blood as they age."

While state and federal standards that constitute safe exposure have continued to be lowered over the last decade or so, lead exposure continues to be widespread in the United States, with more than 1.4 million industrial workers having potential lead exposure. Previous studies have shown that the amount of lead in the body increases throughout the life span, with 90 to 95 percent of that lead stored in the bones. With aging, bones demineralize and stored lead can be recirculated into the bloodstream.

The Pitt researchers studied 58 men with prior workplace exposure to lead. The study group ranged in age from 40 to 76 and had not worked with lead, on average, for the preceding 10 years. The workers were then divided by age into three groups. Correlations between blood lead and bone lead were highest in the older age groups, meaning the combination of age and bone lead significantly predicted an increase in current blood lead levels. This suggests that lead from the bones is an important source of lead circulating in the blood. Older workers with prior exposure to lead may therefore face an additional neurotoxic hazard long after exposure has ended.

"Lead is a powerful neurotoxin that affects people of all ages. Recent studies have shown impairment in both children and adults at concentrations previously thought to be safe. Lead attacks many systems in the body. The most important target is the central nervous system. Increased measures to prevent exposure will be necessary to achieve the optimal goal of zero blood lead in the U.S. in the next decade," said Dr. Morrow.

Co-authors of the study include Herbert Needleman, M.D., Christine McFarland, Kim Metheny and Michael Tobin, all from the University of Pittsburgh.

Dr. Morrow was supported by funding provided by the National Institute for Occupational Safety and Health.

Western Psychiatric Institute and Clinic (WPIC) is considered to be one of the nation's foremost university-based psychiatric care facilities and one of the world's leading centers for research and treatment of mental health disorders. WPIC houses the Department of Psychiatry of the University of Pittsburgh School of Medicine and is the flagship of UPMC Behavioral Health, the psychiatric specialty division of the University of Pittsburgh Medical Center.

University of Pittsburgh Medical Center