Mercury Warning: Fish in Delaware are Unsafe to Eat
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Once mercury is released into the environment, it vaporizes quickly and can be transported long distances in even light winds and is able to circle the globe. The “atmospheric lifetime” of mercury is 18 months.
Mercury settles to the earth in rainfall in a process called “atmospheric deposition.” Once in contact with the earth, it enters aquatic environments. It is here that mercury becomes truly dangerous. Through natural processes in wetlands, lakes and other aquatic environments, microorganisms and aquatic plants convert mercury into “methylmercury.” This highly-toxic form is much more dangerous than the elemental mercury in your fever thermometer.
Pathway to Mercury Exposure—Contaminated Fish
Methlymercury “bioaccumulates” in fish and shellfish. As larger fish eat smaller fish, they concentrate it in their flesh. Large predatory fish (such as tuna, sharks and swordfish) have the highest levels of mercury. Even fish in our local waters, including the Atlantic Coast, Delaware River, Delaware Bay, Inland Bays, Saint Jones River, Silver Lake in Dover, Prime Hook Creek and Waples Pond are so contaminated with mercury that the state has issued fish consumption advisories.
When humans eat mercury-contaminated fish and shellfish, they are eating super-concentrated doses of highly-toxic methylmercury. Mercury passes through the blood-brain barrier, damaging the brain, and can pass through the placental barrier and concentrate in an unborn child, impacting his or her neurological development.
The best way to prevent mercury exposure is to remove the original sources of contamination from the environment and to avoid eating contaminated fish.
Where does mercury come from?
The largest sources of mercury emissions into the environment are from coal-fired power plants and gold production. In addition to safe disposal of thermometers, clean renewable energy, such as solar energy and wind power, can reduce the amount of mercury that is released into the environment.
Photo credit: Amy Roe
