Women exposed to high levels of lead (PB2+) continue to show reductions in bone density even years later, according to a report from the U.S. Centers for Disease Control and Prevention (CDC). Bone's tendency to act as a storage site for lead may result in an increased risk for osteoporosis.
"Bone stores of lead are dynamic and may become bioavailable, especially when changes in bone turnover occur during different stages of life," explained Vijayalakshmi Potula, Ph.D., and Wendy Kaye, Ph.D., from the CDC's Agency for Toxic Substances and Disease Registry in Atlanta (Journal of Women's Health, July 2005, Vol. 14:6, pp. 461-464).
Previous findings have shown that after one month of exposure to low lead levels, the substance is incorporated into bone mineral. A year's worth of exposure may induce osteopenia, the authors stated. They followed up on 108 women who participated in the 1994 study that assessed bone mineral density (BMD) levels in those working at a lead mining and smelting facility in Bunker Hill, ID. That survey found that the postmenopausal, female mine workers had a reduction in the average spine BMD (-0.062 g/cm2) compared to unexposed women.
Potula and Kaye were able to follow up with 68% of the original 108 participants in 2000. They found that six years after the original baseline survey these women still had higher blood lead levels and higher parathyroid hormone (PTH) levels. When levels of the latter become elevated, PTH extracts calcium from the bones and moves it into the blood, thereby increasing the rate of bone resorption and adversely affecting lumbar spine BMD.
In addition, "small increases in blood lead level are associated with decrements in neurocognitive performance, increased risks of atherosclerosis, increased incidence of hypertension, and increases in risk of peripheral arterial disease," they wrote.
The authors urged all physicians to obtain occupational history that assesses potential lead exposure in their patients. While the majority of women don't spend much time down a mine shaft, exposure to lead can occur in less obvious forms -- ceramics, water supply, and common household paints.
The National Osteoporosis Foundation does not make specific screening recommendations for women who have a high level of exposure to lead. It suggests that all women age 65 and older, regardless of risk factors, undergo screening for osteoporosis at least every two years.
By Shalmali Pal
AuntMinnie.com staff writer
October 4, 2005
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