View Full Version : New Study On Mercury Contamination Finds ‘Tempered’ Good News

05-14-2009, 04:59 AM
New Study On Mercury Contamination Finds ‘Tempered’ Good News

Posted by Interactive Desk (http://zip06.theday.com/members/Interactive-Desk.aspx) on May 13 2009, 11:04 AM

By Jason Vokoun, Special to the Times:
For many Connecticut outdoor enthusiasts, spring means the beginning of fishing season. This year, anglers will be pleased to know that a new University of Connecticut study has found that mercury contamination levels in the flesh of largemouth bass from Connecticut lakes were lower in 2005-2006 than levels documented a decade earlier.
While this is good news regarding the quality of fishes and the aquatic environment, the study also reveals that despite the lower mercury contamination, the toxic metal is still present at levels that merit a continuation of the current statewide fish consumption advisory.
The Connecticut Department of Public Health advises young women who are or may become pregnant, nursing mothers, and children under age 6 to limit eating locally caught freshwater fish to one meal per month because of the risks poised by mercury to this high-risk group of people. State officials have advised the rest of the public to limit consumption to one meal per week. The statewide consumption advisory excludes stocked trout that are raised in hatcheries and released in spring and fall stocking programs into ponds, lakes, rivers, and streams around the state.
There are, of course, many health benefits to eating fish. Eating fish you catch is a longstanding cultural heritage that helps us understand both where food ultimately comes from, and the value of conserving a clean and healthy environment. Fishing is also fun, relaxing, and a great way for families to enjoy the outdoors.
Connecticut and U.S. health officials believe the widespread elevated levels of mercury in freshwater fishes found in the Northeast are largely the result of mercury released from coal-burning power plants—many far away from Connecticut waters. Once in the air, the toxic metal can travel huge distances before entering soil and water.
Once mercury settles into watersheds and enters the water, it is transformed by water-borne bacteria and then can enter algae, which are eaten by plankton, which are eaten by little fishes, which in turn are eaten by bigger fishes like largemouth bass. At each step in the food chain, the mercury becomes more concentrated; this process is called bioaccumulation. Mercury is a naturally occurring metal but becomes toxic to human and animal consumers when highly concentrated in fish flesh.
Because of mercury’s toxicity, both federal and state public officials have agreed to efforts to reduce manmade mercury emissions in power plants. The federal Clean Air Act has imposed stricter standards on coal-burning plants, and smokestack “scrubbers” have been placed in many facilities in the upper Midwest and Canada that send mercury towards Connecticut.
The new UConn study suggests that these efforts are possibly starting to pay off. The study is the second statewide assessment of mercury levels in fishes from Connecticut lakes and the first to compare testing data from 1995 to the present. Funding for the current study was provided by the Connecticut Department of Environmental Protection.
Lakes were chosen from every region of the state and fish were collected by electrofishing, a sampling technique that generates an electric field in the water to stun fish so they can be easily netted. Additional fish were donated by anglers participating in fishing tournaments.
Largemouth bass were used for the study because these predators represent the top of the food chain in most Connecticut lakes and therefore have the highest expected levels of mercury contamination.
The UConn study also experimented with a new non-lethal biopsy method to determine mercury levels in the fish. Following existing protocols, fish were euthanized and the fillet (the muscle meat on one side of the fish) was removed and then blended together and analyzed for mercury contamination levels. Small biopsies were removed from random fillets prior to blending and the experiment showed that the biopsies could be taken from fish and used to determine mercury levels that are comparable.
The contamination is pervasive and public health officials believe that even if all manmade mercury emissions were stopped, it would take 15 to 20 years before mercury levels in the environment and fish would drop to low enough levels for nonmoderated human consumption. Future monitoring will be needed to determine when the consumption advisories based on mercury can be relaxed and hopefully, one day, removed.
There are particular water bodies in Connecticut that have additional advisories due to higher than average mercury levels and other environmental contaminants. Anglers should refer to www.ct.gov/dph or call 877-458-3474 for more information. A summary of current consumption advisories is always included in the annual angler’s guide distributed by the Department of Environmental Protection Fisheries Divisions; the guide is available at most town clerk’s offices and tackle stores as well as online at www.ct.gov/dep.