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Fish

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Illustrative photo for story.   (Credit:  Brianna Piche) Illustrative photo for story. (Credit: Brianna Piche)

By Mark Clements | LSU Student

Louisianans pride themselves on fine fish – from Cajun cuisine to seafood specialties – but not everything is a delicacy deep in the waters in and off the Pelican state.

Being top-dog on the food chain in a region that hinges on the success of fisheries puts Louisianans at a greater risk of being exposed to a harmful element found in nearly every body of water – mercury.

Mercury, according to Inspection Division Administrator at the Department of Environmental Quality Chris Piehler, is a naturally occurring element found in the waters of Louisiana that originally spilled over from the earth's crust.

Piehler said that through the years, the movement of the dangerous, versatile metal – which can be found in the air, dirt and water – has been accelerated by several man-made practices.

"It's been here long before we were here and it'll be here long after we're gone," Piehler said. "Not only are there natural processes that move mercury around, but there are also man-made processes that have moved mercury around a great deal because it's been used in so many different things."

The movement of mercury isn't the problem, though. The real issue arises when the element enters into the food chain through a process called bio magnification.

When mercury is found in the bottom of natural water bodies under certain conditions Piehler called "not abnormal at all," it can be converted into its organic form, methyl mercury, where it readily slips into the food chain, beginning with small bacteria that ingest the element.

These bacteria, in turn, are eaten by tiny aquatic insects, eaten, in turn, are eaten by smaller fish, which are eaten by larger fish, and so forth, until the mercury reaches the very top.

"Once it gets into the food chain, bio magnification allows for it to be found in greater concentrations the higher up the food chain that you go," Piehler said. "That's when we get the exposures to humans through the consumption of seafood."

So how dangerous is the consumption of mercury?

Since mercury is a neurotoxin, exposure at dangerous levels would primarily affect the nervous system, which Piehler said puts young children and developing fetuses at the biggest risk.

"Typically the symptoms include numbness in the extremities, pain in legs and arms, nervousness," Piehler said. "[Children's] nervous systems are still growing, and exposure to mercury more than a certain amount can impair the ability of that child's nervous system to develop and may end up making the child deficient from a learning standpoint later on in life."

Piehler added that DEQ teams up with the Department of Wildlife and Fisheries and the Department of Health to sample mercury levels around Louisiana and, if necessary, to take action.

The trio of teams developed a Human Health Risk Assessment analyze the mercury levels in different fish, and issue warning advisories if the results reach potent levels.

"All of the agency and agency heads will look at [the findings] to determine if it's appropriate and then jointly issue that advisory to the public," Piehler said. "If all of the criteria in the risk assessment – how much time, how much do you weigh, how much do you eat – are at [dangerous] conditions, then we would issue an advisory."

To date, 49 mercury advisories have been issued by the DEQ on different fish tissues, with some of the more well-known species being the bowfin, certain breeds of catfish and the popular sporting fish, largemouth bass.

The state issued an action plan in 2007 to help reduce the mercury levels in Louisiana waters and to much success, converting two power plants to non-mercury technology and greatly reducing the mercury content in Louisiana waters.

But Piehler said the action isn't limited to the government, adding there are two vital things citizens can do to avoid the mercury problem.

"The first [thing] is we can identify sources of mercury to the environment and reduce them, and that's part of what DEQ does," he said. "The other thing people can do is to learn about mercury, read the advisories … because it tells you where to be careful when you fish there. If citizens become aware of the mercury issues and where it becomes a problem, they can manage their behaviors and their consumption activity so that they will not have to worry about risks associated with mercury exposure."

Since the issue extends past just fishing in the area, Kristina Bradford, community relations coordinator for the Whole Foods Markets in the area, said her stores take extra steps to ensure customers are well-informed on their seafood products before buying.

"We have brochures that we keep in our seafood departments to educate our guests about the levels of mercury in certain types of fish, especially when it comes to young children or pregnant women," Bradford said. "We're look at providing the highest quality fish and seafood available."

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