Nature and the Environment
Mercury in the Environment
By Ruth and Bob Haag

In the past few years, we have been hearing about mercury contamination in the environment. Mercury was the Roman god of trade, profit and commerce. He quickly flew from place to place. His name has been used for the planet Mercury, because it appears to move quickly in the sky, and the element mercury, which is liquid at room temperature and thus able to flow quickly. Mercury is sometimes called “quicksilver.

Mercury, Science Teachers and Toys

Most of us who are over 50 years old have some stories about the metal mercury. We can tell how our science teacher would bring out some mercury and roll it around in his hands, showing us this marvelous metal that is liquid at room temperature. We also had toys with mercury in them. There was a plastic maze with a mercury droplet that we had to work through the maze. We also used mercury thermometers, and sometimes they broke.

Mad as a Hatter

The Mad Hatter in Alice in Wonderland was not entirely fiction. During the industrial revolution, everyone wore hats, which were often made of felt. The felt was manufactured from animal fur. In order to remove the fur from the pelts, the hatters put the pelts in a solution of mercury nitrate. Inhaling mercury vapors affects the nervous system, and can lead to muscle twitching, a lurching gait and trouble speaking and thinking clearly. Hatters developed these symptoms. By 1943, all use of mercury in hat making had ceased.

If Not from Hats, where Is Mercury Coming From?

According to USGS Fact Sheet FS-095-01, coal burning power plants produce 50 tons of mercury per year, and this accounts for 13-26% of the total airborne emissions of mercury in the United States. Another source notes that this is 40% of the man-made total. Based on these figures, 35-66% of the mercury released is produced by natural sources, which include volcanoes, forest fires and weathering of mercury-bearing rocks. Inorganic elemental mercury that is released to the atmosphere is thought to wash into streams, where it is organically changed by bacteria into methylmercury, the most common organic mercury compound found in the environment.

Methylmercury Behavior

Methylmercury is dangerous to humans if ingested in large quantities. It can produce symptoms of mercury poisoning. Methylmercury accumulates as it goes up the food chain. Larger fish have the potential to have more methylmercury in their systems than smaller fish. Luckily, methylmercury can be removed from the body naturally, but it takes months to a year to do so. Pregnant women who eat large quantities of fish containing methlymercury are at risk of harming the development of the fetus, who can be born with severe disabilities. If you eat fish containing methylmercury, your body will remove it, but slowly. Partially due to mercury levels, we in northern Ohio are currently advised to eat fish from Lake Erie only once a week. You can find specific fish advisory information at: www.epa.state.oh.us/dsw/fishadvisory/.

Mercury in Old Fillings

Every once in a while, there arises a concern with fillings for teeth that were once created with an amalgam of mercury, silver, tin, copper and zinc. In addition, cadmium, indium, palladium and lead have been used. Here again, the mercury is not a problem, but mercury vapors could be. The biggest risk-taker was the dentist who used to mix these fillings in his office. These fillings were used because they cost much less than gold, and were malleable and durable. Now, a range of plastics has taken their place.

Medical Applications

Mercury-containing medicines, such as the Blue Mass pill and Mercurochrome, were used in the 1800s and 1900s. A study released in 2001 in Perspectives in Biology and Medicine suggested that Abraham Lincoln used the Blue Mass pill, and had violent rages caused by them. He stopped taking them when he became president, and reportedly returned to a more normal condition. Mercurochrome was a red tinted mercury-based antiseptic. Many of us can recall the use of it on cuts as children, before it was banned in the United States.

Cleaning up Mercury Spills

Inorganic mercury, like we played with in science class, is still present in older thermometers and barometers. While inorganic mercury is only moderately absorbed through the skin, and often can pass through the digestive system unabsorbed, breathing the vapors for a long period of time is a danger. Thus, the biggest concern during a spill of mercury is to remove people from the area so that they do not breathe the vapors. If vapors are inhaled over a long period of time, they can cause tremors, gingivitis and excitability. Spilled mercury can be cleaned up by changing it into a nonhazardous organic salt. A product named HgX is designed to be spread over mercury to cause this chemical change. Fine powdered sulfur or zinc can also be used. Spilled mercury should never be vacuumed or swept up, because this will disperse the droplets and increase the amount of vapor in the air.

What To Do with Your Mercury?

You can check with your local Solid Waste District, as many have an exchange program for mercury thermometers. You would also want to call them in the event of a mercury spill.

Information Sources: Wikipedia, State of Michigan Department of Environmental Quality, US Environmental Protection Agency, publicaccess.cuthelp.com, US Geological Survey, WebCare.md, Erie-county-ohio.net, USGS Fact Sheet FS-095-01, National Geographic News.