by Joyce Jakubiak
MADISON (3/15/97) -- Commercial scallop divers in Maine are well aware that the tasty marine mollusk is getting increasingly hard to find. What they may not know is that making more dives to find the scarce scallop could be bad for their health.
The demanding regimen of the Maine divers puts them at risk of developing a painful bone disease later in life, according to UW Sea Grant-supported researcher Charles Lehner.
Lehner, a scientist at UW-Madison’s Medical School, has been monitoring the prevalence of dysbaric osteonecrosis, or bone necrosis, in more than 400 Maine scallop divers who are considered a high-risk group.
Lehner is conducting his study in collaboration with the Northern New England Hyperbaric Medical Center in Sanford, Maine. The study is modeled on similar research in Japan in the early 1970s that found a high prevalence of bone necrosis, or bone death, among Japanese diving fishermen.
The scallop divers in Maine are comparable to the Japanese divers, Lehner said, because they report a high incidence of the bends, a form of decompression sickness. That’s because such divers often perform up to 20 dives a day at depths of 60 to 100 feet.
"Our concern is that with repetitive diving one can accumulate substantial quantities of dissolved nitrogen in tissues, which upon decompression can cause bubble formation," Lehner said. "If bubbles form, then injury can occur in the bone tissue."
Nitrogen bubbles can be painful when they expand and can cause tissues in arm and leg bones to die. Later, the ends of these weakened bones can break, causing disabling pain. This condition can take anywhere from two to 15 years to develop, Lehner said.
Although his research is preliminary, Lehner said that two of the 12 Maine scallop divers who reported limb bends have developed bone necrosis.
Lehner is quick to note that the Maine divers’ habits set them apart from most of the two million recreational divers in the United States who don’t generally dive as frequently or as deep. At present, scientists believe that the risk of recreational divers developing bone necrosis is very low.
But commercial divers can lessen their risk of developing the bends -- and necrosis -- by diving less often and not so deeply. More importantly, Lehner said, it’s crucial that when divers get the bends they undergo treatment in recompression chambers.
"First of all, this will permit the diver to decrease the pain associated with limb bends," Lehner said. "Secondly, it allows blood that may have been stopped by the formation of nitrogen bubbles to flow back into the tissues."
Without prompt recompression treatment, he said, bends-affected divers face the prospect of bone necrosis and long-term disability.
Created in 1966, Sea Grant is a national network of 29 university-based programs of research, outreach and education dedicated to the protection and sustainable use of the United States' coastal, ocean and Great Lakes resources. The National Sea Grant Network is a partnership of participating coastal states, private industry and the National Sea Grant College Program , National Oceanic & Atmospheric Administration , U.S. Department of Commerce . The University of Wisconsin Sea Grant College Program is administered by the Sea Grant Institute on the UW-Madison campus in Madison, Wisconsin.
Posted 3/15/97 by S. Wittman
All contents copyright 1997 University of Wisconsin Sea Grant Institute
http://www.seagrant.wisc.edu/news/divenews.htm
