By Amber Tucker
On September 12th, staff from EPA visited Haskell Indian Nations University in Lawrence, KS, not in an attempt to crack a top secret code (see “Mercury Rising” on IMDB), but rather to convene in an effort to learn about another kind of rising mercury. Hosted by Haskell, with support from the National Atmospheric Deposition Program (NADP), US EPA Region 7, and the Kickapoo Tribe in Kansas, the “Mercury in the Environment” Symposium served as a gathering of minds from Tribal, Federal, and undergrad Haskell students, all ready to learn and discuss the effects of mercurial deposition and monitoring in our environment. Over the next two blog posts I hope to share with you information about mercury in the environment, and how EPA and Tribal Nations in the Region are studying its presence in the environment
Mercury is a naturally occurring element (Hg on the periodic table) that is found in air, water and soil. It is an element in the earth’s crust, which humans cannot create or destroy. Contrary to what some Queen fans may tell you, “Freddie” is not an officially-recognized form of mercury. Pure mercury is a liquid metal, sometimes referred to as quicksilver that volatizes readily. It has traditionally been used to make products like thermometers, switches, and some light bulbs. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds. Elemental or metallic mercury is a shiny, silver-white metal and is liquid at room temperature. If heated, it is a colorless, odorless gas.
Many of us might recall mercury being in thermometers, some older generations may even recall taking those little balls of that silver stuff out of said thermometers and playing with those mystical little balls of silver that weren’t quite liquid but not quite a solid either. My dad recalled rolling it around in his hands and watching it disappear. With the knowledge we have today, it goes without saying that that’s a really bad idea.
Mercury is found in many rocks, including coal. When coal is burned, mercury is released into the environment. Coal-burning power plants are the largest human-caused source of mercury emissions to the air in the United States, accounting for over 50 percent of all domestic human-caused mercury emissions (Source: 2005 National Emissions Inventory). EPA has estimated that about one quarter of U.S. emissions from coal-burning power plants are deposited within the contiguous U.S. and the remainder enters the global cycle. Burning hazardous wastes, producing chlorine, breaking mercury products, and spilling mercury, as well as the improper treatment and disposal of products or wastes containing mercury, can also release it into the environment. Current estimates are that less than half of all mercury deposition within the U.S. comes from U.S. sources.
Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans. Methylmercury builds up more in some types of fish and shellfish than others. The levels of methylmercury in fish and shellfish depend on what they eat, how long they live and how high they are in the food chain. Birds and mammals that eat fish are more exposed to mercury than other animals in water ecosystems. Similarly, predators that eat fish-eating animals may be highly exposed. At high levels of exposure, methylmercury’s harmful effects on these animals include death, reduced reproduction, slower growth and development, and abnormal behavior.
Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. Research shows that most people’s fish consumption does not cause a health concern. However, it has been demonstrated that high levels of methylmercury in the bloodstream of unborn babies and young children may harm the developing nervous system, making the child less able to think and learn. Methylmercury is a deceptive little bugger when it comes to cell recognition; it’s completely absorbed in the human GI tract, where its half life in the blood stream is 50 days. Its chemical structure is very similar to that of the essential amino acid methianine, which allows it to sneak past the bouncers at the front door of our cells, but when it gets in the door and incorporates into proteins, it wreaks havoc and results in abnormal cellular structure and function; a case of mistaken identity that wreaks havoc on those with developing systems. For additional info on the health effects of mercury, click here.
EPA works with the U.S. Food and Drug Administration (FDA) and with states and tribes to issue advice to women who may become pregnant, pregnant women, nursing mothers and parents of young children about how often they should eat certain types of commercially-caught fish and shellfish. Fish advisories are also issued for men, women, and children of all ages when appropriate. In addition, EPA releases an annual summary of information on locally-issued fish advisories and safe-eating guidelines to the public. Fish is a beneficial part of the diet, so EPA & FDA encourage people to continue to eat fish that are low in methylmercury. For more information, please click here .
In my next blog post, I will discuss what was covered in the Symposium and how we can see the Mercury Fall, not just as temperatures cool as we enter Autumn, but as we move forward as partners.
Amber Tucker is an Environmental Scientist who serves as a NEPA reviewer for EPA Region 7. She is a graduate of Haskell University and serves as Region 7′s Special Emphasis Program Manager for Native American Employment Programs.