1. Mercury and the Environment Bio Sci 2B

2. Mercury: The Element   Liquid at room temperature   Atomic #: 80   Atomic Mass: 200.59 g   “Quicksilver”   Density: 13.6 g/mL

3. The Different Forms of Mercury   Exists in different forms: elemental, inorganic, and organic mercury   Mercury alloys easily with other metals such as gold, silver, and tin (amalgams).   Important mercury salts include HgCl2, Hg2Cl2, Hg(ONC)2, and HgS (vermillion).   Metallic mercury is used in thermometers, barometers, and fluorescent light bulbs.

4. How Mercury Enters the Environment   Mercury can enter the environment through human activities such as coal burning and product manufacturing. Mercury can also enter the environment from natural sources such as volcanoes.   Globally, 4800 – 8300 tons of mercury are deposited per year due to both natural and human generated causes.

5. Bioaccumulation of Mercury   Bioaccumulation of mercury begins when bacteria in soils convert the mercury to methylmercury, a highly toxic form.   The concentrations of methylmercury in large fish can be over a million-fold larger than in the surrounding water.   The methylmercury is concentrated further up the food chain.

6. Overview of Mercury Health Effects   Almost all people have at least trace amounts of mercury in their tissues. People may be exposed to mercury in any of its forms under different situations.   The effects of mercury exposure can be very severe, subtle, or may not occur at all.   Because young children and unborn fetuses are still developing, they are particularly sensitive to the effects of methylmercury on the nervous system.

7. Methylmercury Effects & Exposure   Organic mercury, such as methyl mercury is more toxic than inorganic mercury.   Symptoms of methylmercury poisoning may include: impairment of the peripheral vision, disturbances in sensations, lack of coordination of movements, impairment of speech, hearing, walking, and muscle weakness.   Methylmercury exposure in the womb, which can result from a mother's consumption of fish and shellfish that contain methylmercury, can adversely affect a baby's growing brain and nervous system.   Impacts on cognitive thinking, memory, attention, language, and fine motor and visual spatial skills have been seen in children exposed to methylmercury in the womb.

8. Statistics and Details   The reference dose the EPA uses is 0.1 µg/kg body weight/day as an exposure without recognized adverse effects. This is equivalent to about 5.8 µg/L of whole blood.   The EPA estimated that 7% of women of childbearing age would have blood mercury concentrations greater than those equivalent to the reference dose (1997).   It is estimated that more than 300,000 newborns each year may have increased risk of learning disabilities associated with in utero exposure to methylmercury.

9. Effects of Other Mercury Compounds   Elemental (metallic) mercury primarily causes health effects when it is breathed as a vapor where it can be absorbed through the lungs.   With large acute exposures to metallic mercury vapor, the lungs may be permanently damaged.   High exposures to inorganic mercury may result in damage to the gastrointestinal tract, and the nervous system.   Long term exposure to inorganic mercury affects the kidneys and can cause tubular necrosis.   Organic mercury compounds are more readily absorbed via ingestion than inorganic mercury compounds.

10. Reducing Mercury Exposure   Fish consumption advisories in 44 states have limited or eliminated the fishing of certain highly mercury contaminated fish.   The FDA maximum permissible level is 1 part of methyl mercury in a million parts of seafood (1ppm).   On March 15 th, 2005. the EPA issued the Clean Air Mercury Rule to reduce mercury emissions from coal-fired power plants. This rule will hopefully reduce emissions by 33 tons, nearly 70% when fully implemented.   Medical waste incinerators, which emitted about 50 tons of mercury per year into the air in 1990, have gone down 95% since the EPA issued emission standards for these medical waste incinerators in 1997.

11. Bibliography   www.epa.gov/mercury/ www.epa.gov/mercury/   www.ems.org/mercury/fish.html www.ems.org/mercury/fish.html   www.lenntech.com/Periodic-chart-elements/Hg- en.htm www.lenntech.com/Periodic-chart-elements/Hg- en.htm   www.wicca.com/celtic/ stones/images/cinnabar.jpg