SALT LAKE CITY — New study results from the U.S. Environmental Protection Agency show the mercury intake of women of childbearing age across the nation has dropped dramatically, but the amount of fish being consumed has changed very little.
Drawing on data from the Centers for Disease Control and Prevention, the study suggests that women may be making smarter choices about the fish they eat, which the EPA says is good news because fish remains an important part of a healthy diet.
The survey looked at study results from 1999-2000 and compared those to subsequent surveys carried out from 2001 to 2010. It found blood mercury concentrations dropped 35 percent in women. The number of women with blood mercury levels above the level of concern plummeted by 65 percent.
Such significant decreases indicate, too, that fish consumption advisories put out by state environmental and health departments may be having an effect on the public, although the EPA was cautious to draw that conclusion.
People become exposed to mercury after it is released into the environment and converted to methylmercury in soils and sediments. Over time, it bioaccumulates in fish and shellfish. Exposure in developing fetuses and young children has been linked to adverse effects that include a decrease in IQ and motor function.
Nationally, the EPA study focused largely on the consumption of ocean fish, but it noted that residents also need to be mindful of what is consumed from local waterways such as mountain lakes and streams.
In Utah, there are 12 different fish species in 23 locations that are under the state's fish consumption advisory for mercury. Species include brown trout, walleye, catfish and wiper, but the contamination varies from lake to lake and fish to fish.
The state has had a mercury workgroup since 2005, when the Utah Department of Environmental Quality in partnership with the Utah Department of Health launched its fish consumption advisory program.
John Whitehead, deputy director of the state Division of Water Quality, has chaired the group since its inception, leading the efforts on crafting advisories for what fish are safe to consume at what level by residents.
In its fledgling years, Whitehead said the program garnered quite a bit of attention and concern by the public, who may initially have been alarmed over the mercury advisories.
"As we have gone through the years, I think people are understanding the context of these advisories a little bit better," he said.
Whitehead's division, coupled with the state health department, have to strike a delicate balance of keeping the public informed about the fish consumption advisories in effect due to mercury, yet not dissuading fish consumption.
"Fish is very good to eat and the health benefits are very strong," said Craig Dietrich, toxicologist with the Utah Department of Health's environmental epidemiology program. "One just needs to be mindful of what we are eating."
Dietrich, in fact, convinced his colleagues and other agencies to add information to the advisories when they are issued that includes the consumption amounts for non-sensitive populations as well. People who are not in the risk categories, such as adult men, can consume three times as much fish.
"The dangers of mercury ingestion drop away dramatically at that point," he said.
Dietrich said he believes the study results help to drive home the benefits of the health advisories by raising public awareness and helping consumers make informed choices.
Curiously, the study did find that increasing age and income led to higher concentrations of blood mercury levels among women — which Dietrich said makes sense.
"Shark is expensive. Ahi tuna is expensive," he said. "It is something that is reflective of economics. Tilapia? Not so much."
Generally, women of child-bearing age and young children are advised to refrain from eating shark, swordfish, king mackerel or tilefish because they contain higher levels of mercury. Predator fish that live longer and grow to be larger have the higher concentrations of mercury, such as blue fin tuna, sea bass and halibut.
Fish that are commonly eaten that have the lowest levels of mercury are canned light tuna, shrimp, salmon, pollock and catfish.
The EPA noted that its study is in support of making fish safer for consumption, with efforts that embrace a three-pronged approach that encourages development of statewide mercury reduction strategies, reduction of the air deposition of mercury and improving public information and notification of fish contamination risks.
In 2013, the agency took two substantive steps to make fish and shellfish safer to eat by proposing new guidelines for effluent discharges from steam electric power plants and by issuing a new mercury and air toxics rule. The rule sets emission limitation standards for mercury emitted from power plants.