A new study about to be undertaken by the University of Rochester Medical Center may finally shed light on the role environmental lead exposure plays in bone maturation and loss. The researchers involved say that a growing body of research indicates that lead exposure could be a major factor in an older person's risk for osteoporosis. Scientists have known for some time that the human skeletal system is a storehouse for lead in people who were exposed to high levels in their childhood, but it was believed that this storage did not cause ill effects. But recent studies have now shown just the opposite to be true, and that lead in bone can actually trigger a chain reaction that first accelerates bone growth, and then eventually limits it, so that a high peak bone mass is not achieved. Such a chain of events, say the researchers, can predispose a young person to develop osteoporosis later in life.
Osteoporosis is a bone disease that predominantly occurs in women, affecting one-in-three American women over the age of 65. It is characterized by low bone mass that eventually leads to fractures, mostly of the hip and vertebrae.
The researchers explained that the pattern of growth in the skeleton determines the peak skeletal density of an individual, and this level is established by the time most people reach 20. "As a child, lead appears to accelerate bone development and maturation, so that lead-exposed children actually have a higher bone density than those not exposed to environmental lead," said Rochester co-researcher James Campbell. "But, we believe this higher bone density effect is short-lived, and in fact, we believe it actually prevents these children from achieving an optimal peak bone mass later on in life."
"When everyone begins to lose bone mass starting at around age 50, lead-exposed individuals are at a higher risk for bone fractures and osteoporosis - and probably at an earlier age than the typical osteoporosis patient," added study director J. Edward Puzas.
Understanding when lead-exposed individuals will plateau in bone growth, and at what age they will begin to lose more bone as older adults, is the focus of the new study. "We believe that somewhere around age 20, we'll begin to see low-lead exposed individuals surpass high-lead exposed individuals in bone mass density," Campbell said. "Then, in the 50 to 60 age group - the age at which any individuals will begin to experience a natural loss of bone - we expect to see the high-lead exposed individuals losing more bone sooner."
Source: University of Rochester Medical Center
