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Utah Department of
Environmental Quality
With reports of elevated mercury levels discovered in Utah game fish, anglers who subscribe to the adage “hook ‘em and cook ‘em” might be thinking twice before frying up their favorite bass recipe or blackened catfish.
But officials with the Utah Department of Environmental Quality (UDEQ) say the risks should be placed in perspective. Consider, for instance, that only three waterways in the state have tested positive for elevated mercury levels that warrant limiting consumption and that the risks of any problems from mercury are very low if consumption guidelines are followed.
So far, environmental monitors have tested about 159 sites statewide, with only three locations where fish consumption advisories have been needed. With the results now available from about 45 percent of the tests, unacceptable mercury levels have been found in only about 10 percent of the fish, said John Whitehead, assistant director of the Utah Division of Water Quality and chairman of the Statewide Mercury Work Group.
“This doesn't mean people should stop fishing, and eating fish,” said Whitehead. “The fish advisories are meant to alert the public so they can make informed choices and where needed, simply limit the amount of fish you are eating.”
Anglers will want to exercise caution if fishing for largemouth bass at Gunlock Reservoir in Washington County, brown trout in Mill Creek in Grand County, and channel catfish in the Green River in Desolation Canyon. Tests there have shown mercury values that exceed U.S. Environmental Protection Agency levels of concern if these fish are eaten more than a few times each month for a long period of time. UDEQ and the Utah Division of Wildlife Resources (DWR) have issued fish consumption advisories for those waters.
That advisory cautions that women who are pregnant or may become pregnant, nursing mothers and young children should not eat more than one 4-ounce serving per month of fish from Gunlock, Mill Creek or Desolation Canyon. Mercury levels are high enough in fish from Ashley Creek that no amount is considered safe.
For everyone else, consuming mercury-tainted fish should not be a problem if the portions are small and infrequent. The advisory recommends no more than two 8-ounce servings per month of fish from Gunlock, and the Green River no more than three 8-ounce servings per month of fish from Mill Creek.
For the avid hunter and fisherman, concerns have been raised about the cumulative effects of mercury in the natural food chain. In addition to fish, some species of waterfowl - northern shovelers and common goldeneyes - on the Great Salt Lake have tested positive for elevated levels of mercury.
“The problem with mercury is that it bio-accumulates,” Whitehead said. “Very low concentrations of mercury get into waterways and are picked up by smaller organisms that fish and waterfowl eat. Mercury accumulates in the muscle tissues of these fish and waterfowl in much higher concentrations than the water and then is passed on to those who consume this wildlife.”
Where is the mercury coming from?
Investigations are underway to determine the source of the mercury contamination. Whitehead said one common source is air pollution, both inside and outside of Utah. Air emissions of mercury occur as a result of natural phenomena, like volcanoes, forest fires and geothermal activity. It also can result from man-made activities like incinerator burning, scrap metal recycling and mining processes.
“UDEQ is working with neighboring states to learn more on how releases of mercury from sources in nearby states, including the gold mines in Nevada, may be impacting the state of Utah,” Whitehead said. He added that state regulators will “implement an aggressive monitoring program to determine if there are other areas in Utah where fish or waterfowl would pose a human health risk if consumed.”
Utahns also should be aware other sources of mercury in their cars, homes and products we use everyday need to be properly disposed of in order to avoid adding to our ongoing mercury problems. These include mercury switches in automobiles and mercury thermometers. For more information on proper disposal or recycling, visit http://www.deq.utah.gov/issues/Mercury/index.htm.
How Much Mercury is too Much?
Jason Scholl, a toxicologist at the Utah Department of Health, said the amount of mercury tends to increase with the age and size of the fish. Fish that consume other fish have higher levels of mercury.
Most of that mercury is methylmercury, which is rapidly absorbed into the body after consumption (about 90 to 100 percent is absorbed). The body transforms methylmercury into inorganic mercury, which can remain in the body for several months.
“The nervous system is very sensitive to all forms of mercury,” Scholl said. “In poisoning incidents that occurred in other countries, some people who ate fish contaminated with large amounts of methylmercury or seed grains treated with methymercury…developed permanent damage to the brain and kidneys.”
Lab tests also show mercury can change blood pressure and heart rates, adversely effect developing fetuses, increase the chance of abortions and stillbirths, and affect male reproductive organs, Scholl said.
But officials say there is no need to be alarmed by small amounts of mercury, only more aware of the health risks of over-consumption. Mercury is a natural part of the Earth's ecosystem, and it is found in minute quantities in many different foods consumed daily. For example, there is currently a nationwide advisory concerning the consumption of shark, swordfish, King Mackerel, or tilefish. More information on the national fish advisory can be found at http://www.cfsan.fda.gov/~dms/admehg3.html (opens in a new window).
“Even canned tuna fish we all get from the grocery contains some mercury,” Whitehead said. “Our job as consumers is to be aware of the concerns and issues in all food we eat and to make intelligent choices.”
Mercury contamination is a nationwide problem, and Utah officials take it seriously.
UDEQ began collecting fish in 2000 under a program aimed at looking at a broad variety of issues with mercury being only one of several hundred items being studied. Due to the huge amount of data collected in this program there has been a backlog in the testing because tissue samples had to be sent to an out-of-state EPA lab for processing. UDEQ recently purchased a $50,000 mercury analyzer for the Utah Department of Health State Laboratory to analyze the samples more rapidly and report the results to the public in a timely manner.
State officials are also reaching out to the public, which has become alarmed over the reports of mercury risks. An 18-member Mercury Work Group was created with officials from federal, state and local governments, conservation groups, sportsmen, businesses and other interested stakeholders. The Work Group is developing a standardized sampling strategy for collection and analysis.
More Utah fisheries may be added to the advisory list as more test results come in. Officials are planning a broad testing strategy for Lake Powell, one of the state's premier fisheries.
“We hope to look at areas where most of the fish are taken,” Whitehead said.
The latest information about fish consumption advisories is available at www.deq.utah.gov/issues/Mercury. For more information about the health effects of mercury, visit www.atsdr.cdc.gov/tfacts46.html (opens in a new window).
The Natural Resources Defense Council also has a “mercury calculator” for fish eaters on its web page at www.nrdc.org (opens in a new window) .
Mercury advisories aren't meant to put a damper on fishing. But they can serve as a reminder not to over-consume your favorite game fish, no matter how tasty the recipe.