[lake]The mitten state is famous for its five great lakes (remember H.O.M.E.S.?) and many inland bodies of water. With warm weather finally here, people around the state are getting their fishing licenses and reeling in potential supper from these various freshwater sources. But should they be eating the fish they catch?
The amount of contamination in fish depends on the type, size and location of the fish, according to John Hesse, an adjunct faculty member for MSU’s Department of Fisheries and Wildlife and the man responsible for managing Michigan’s fish consumption advisory program for much of his career. “What people need to know is that while there are some health risks from eating certain kinds of fish, there are also health benefits that fish are known for,” Hesse said. While fish is a great source of omega-3 fatty acids, that promote cardiovascular health, what about those contaminants? Do they outweigh the good stuff?
History senior Rita Stephenson doesn\’t know where the fish she eats comes from, but she\’s not losing sleep over it. “I’m not worried about contamination because the FDA is supposed to regulate that stuff,\” she said. \”I don’t know anyone who has been poisoned from seafood, so it’s not a big concern of mine.”
A mercury invasion
Mercury was once a widely used element. Nearly every American household had mercury in items such as thermostats, batteries and paint. In 1970, however, a graduate student from Norway found that mercury was contaminating the fish in southeast Michigan, making them hazardous to humans. The contamination came from a Canadian factory that discharged anywhere from 200 to 1,000 pounds of mercury into the St. Clair River daily. “This is a huge amount considering one thermometer contains enough mercury to contaminate a 20 acre lake,” Hesse said.
After this discovery, Michigan became the first state to provide an advisory about mercury contamination in fish, warning consumers (especially women and children) to avoid eating certain types of fish from the contaminated areas. Since then, mercury use in the U.S. has decreased by about 85 percent, and factories known to discharge large amounts of mercury into the environment have eliminated mercury use. Tests have shown that mercury contamination in fish in southeast Michigan downstream from polluting companies have declined 90 percent over the years. “Since mercury is rarely used anymore in the U.S., I’m not worried about contamination in fish,” anthropology senior Emily Rinck said.
Mercury, however, continues to be problematic in inland lakes. Michigan has approximately 11,000 inland lakes, and of those, 70 percent are estimated to have mercury contamination. “In the first few years after the discovery of the problem in inland lakes in 1980, we were only able to test about 200 lakes,” Hesse said. “It would take us nearly 250 years to test all of the lakes, so it’s not practical to keep tabs on all of them.” The state has been checking several lakes on a regular basis to detect any downward trends since significant deduction of mercury has occurred. Burning coal to generate electricity is the major source of mercury to the environment. “Control of this source may be necessary before the widespread contamination of inland lakes is solved,” Hesse said.
Men are from Mars, women should avoid mercury
Although mercury can be harmful and potentially lethal at high exposure, women and children (mainly women of childbearing age and children under 15 years of age) are especially at risk. A fetus in the womb is four times more sensitive to mercury poison than the mother, so even a small amount of exposure can be hazardous. Some symptoms of mercury poisoning are weakness, fatigue, memory loss, headaches, narrowed vision, hearing difficulties, numbness or tingling around the mouth, lips, fingers and toes, and in extreme cases, even death. A fetus that has been exposed to mercury in the womb could develop learning disabilities, so pregnant women are advised to watch their fish intake more than the general public.
[dinner]Mercury has a half-life of 70 day in humans, which means all the mercury a person consumes will not stay in the body forever. “The amount of mercury in a person’s system will decrease by half every 70 days as long as there is no additional exposure,” Hesse said. “It will never be completely out of their system, though.” When preparing fish for consumption, there is no way to cut and remove the mercury because it is dispersed throughout the flesh. “I used to tell students that in order to get rid of mercury in a fish, they needed to hang it upside down in a freezer so all the mercury could fall to the head,” Hesse said. “Then I told them to cut off the head to remove all the mercury. I was joking, but they were so gullible.”
Some fish must be a certain length before they are legal to catch and eat. Common predatory fish like northern pike, walleye, and bass from our inland lakes are considered too contaminated to eat unlimited quantities of once they reach the legal length. Additionally, consumption of some panfish species, like perch and crappie, should be limited once they reach nine inches in length. According to the Michigan Department of Community Health, woman and children should not eat these species more than one meal per month because their mercury levels tend to exceed 0.5 parts per million, or ppm. No one should consume fish with an amount of mercury exceeding 1.5 ppm.
The 411 on PCBs
While mercury is primarily the problem in inland lakes, polychlorinated biphenyls, or PCBs, are the biggest contaminant in the Great Lakes. “PCBs are a class of chemicals represented by 209 possible compounds, depending on the number and location of chlorine atoms,” Hesse said. “These individual chemicals are referred to as congeners, some being relatively non-toxic, and others being very toxic.” These chemicals were introduced into the U.S. in 1929, and over 1.25 billion pounds of them have been used since then. Automobile manufacturing, electrical transformers and capacitors, and heat transfer systems are among the industries that used massive amounts of PCBs. Much of these PCBs were dumped into rivers leading to the Great Lakes, and although PCBs were banned in Michigan in 1975 and banned nationally in 1979, the past contamination is still evident today.
Unlike mercury contamination, PCBs are stored in the fatty tissues of fish. “If the fish is cleaned and cooked properly, a majority of the PCBs can be removed,” Hesse said. He recommends removing all of the skin, back and belly fat, and dark fatty tissue along the lateral line of the fillet. MDCH warns consumers against consuming fish with PCBs exceeding 2.0 ppm, the current FDA action level.
For fisheries and wildlife senior Dustin Adams, doing his own catching and preparation is enough precautionary action. “I cut, clean, and cook the fish I catch,” he said. “I don’t worry about contamination because I only eat fish about once or twice a month, and I usually know where it came from.”
There\’s more than sharks lurking in the ocean
The Great Lakes and inland lakes have gotten bad publicity for PCBs and mercury contamination, but ocean seafood can be even more dangerous. Large predatory fish such as swordfish and shark contain an average of 1.2 ppm mercury. In some cases, sharks were over four times the FDA approved mercury level, and swordfish were over twice the approved ppm, yet the FDA has allowed them to remain on the market. Why wouldn’t they enforce stronger regulations or advisories? “[The FDA] lost a court battle,” Hesse said, “and they were ordered to raise their mercury standard from 0.5 ppm to 1.0 ppm due to economic impacts on important marine species like swordfish and tuna, and they have been hesitant to enforce anything since.” Regular meals of shark and swordfish may not be practical for the average college student’s budget (or it just might seem weird to have \”Jaws\” for dinner) but beware nonetheless.
[tuna]The Good > The Bad
College students obviously are not children, but most women in college are of childbearing age, so they should be more cautious when consuming fish. But don’t toss Charlie Tuna to the curb just yet, ladies; fish can pack a lot of nutrition into a balanced diet.
Eating both freshwater fish and seafood can provide great health benefits. Fish is high in protein, low in saturated fat, and high in essential vitamins and minerals. In Michigan, the sport fishing industry employs nearly 20,000 workers and brings in an estimated $1.5 billion to the economy. While there are fish that are slightly contaminated, following guidelines for fish consumption as outlined at www.michigan.gov/mdch can keep consumers informed and safe. Know what you should be eating, what you should avoid eating, and what you are eating; then adjust accordingly. “Don’t be scared to eat fish because of one contamination story you hear,” Hesse said. “Even doctors don’t always know what to suggest for fish consumption, so look to the advisory for necessary information about which fish to eat or not eat.”
Know your fish – being informed lets you have your crab cake and eat it, too.

Leave a Reply

Your email address will not be published. Required fields are marked *