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Focus On Mercury - General Information

Mercury In Our World

(Excerpted by permission from "Mercury: Get Mad Now, Not Later," a 1994 fact sheet by the Western Lake Superior Sanitary District)

MercuryMercury, also known as quicksilver because it is a silver-colored liquid at room temperature, is an element that does not break down. It occurs naturally and is found in very small amounts in oceans, rocks and soils. It becomes airborne when rocks erode, volcanoes erupt and soil decomposes. It then circulates in the atmosphere and is redistributed throughout the environment. (Click here for a listing of the unique and interesting properties of mercury.)

Large amounts of mercury also become airborne when coal, oil or natural gas are burned as fuel or mercury-containing garbage is incinerated. Once in the air, mercury can fall to the ground with rain and snow, landing on soils or water bodies, causing contamination.

Lakes and rivers are also contaminated when there is a direct discharge of mercury-laden industrial waste or municipal sewage. Once present in these water bodies, mercury accumulates in fish and may ultimately reach the dinner table.

Although mercury has been a very useful element, due to its unique properties, it poses a very real health risk-from direct exposure to mercury, as well as from eating contaminated fish. We can minimize this risk by reducing our use of mercury-containing products and properly disposing of mercury-containing waste.

factoryMercury has been used for thousands of years for a wide variety of purposes. Historical uses, which are no longer prevalent, include: preparing felt for hats, controlling mildew in paints, killing weeds as a component of herbicides, and various medical uses-teething powder, antiseptic ointments and syphilis treatment. It's toxic effects on workers in hat factories in the late 1800's led to the term "mad as a hatter." Mercury is still used for folk medicine and ceremonial purposes in several cultures.

Today, mercury is released to the environment from many sources. It is used in household and commercial products, as well as industrial processes. Coal-fired power plants, incinerators, some manufacturing plants, hospitals, dental offices, schools and even homes have all been found to release mercury. In the home, mercury can be found in fluorescent lights, thermostats, thermometers, and even some children's toys. At school, mercury may be in science and chemistry classrooms, the nurse's office and electrical systems. School and home mercury audit activities in this package provide more detailed information on where to find it and what to do about it.

Mercury Health Issues Mercury Health Effects

Two different forms of mercury are of human health concern. Elemental mercury, which is most toxic in its gas form, slowly vaporizes at room temperature and more quickly when heated. Children playing with elemental mercury can be seriously poisoned by breathing the invisible vapor from mercury spilled in carpeting, furniture or other surfaces.

Elemental and inorganic mercury can be transformed into organic mercury by the bacteria in the bottom mud in water bodies. Unlike elemental mercury, organic mercury (often referred to as "methylmercury") can be readily absorbed in humans. The most likely source of methylmercury exposure is eating contaminated fish, which can result in long-term damage to the kidney, liver and central nervous system. Young children and developing fetuses are most at risk.

Organic mercury tends to increase up the food chain, particularly in lakes. The mud at the bottom of a lake may
have 100 or 1000 times the amount of mercury than is in the water. Worms and insects in the mud extract and concentrate the organic mercury. Small fish that eat these critters further concentrate the mercury in their bodies. This concentration process, known as "bioaccumulation", continues as larger fish eat smaller fish until the top predator fish in the lake may have methylmercury levels in their tissues that are up to 1,000,000 times the methylmercury level in the water in which they live.

Most states advise anglers and their families to reduce their consumption of certain types and sizes of fish either statewide or for individual water bodies. Certain types of store bought fish also have elevated mercury levels. The US Food and Drug Administration has issued consumption advisories relating to mercury for mackerel, swordfish, tilefish, and tuna.

Mercury and Children's Health

The greatest risk of mercury poisoning is for fetuses and young children because their nervous systems are still developing. They are four or five times more sensitive to mercury than adults. Damage occurring before birth or in infancy can cause a child to be late in beginning to walk and talk, and may cause lifelong learning problems. Unborn children can be seriously affected even though the methylmercury causes no symptoms in their mothers.

Mercury Exposure from Cultural and Religious Practices

In the United States, certain Afro-Caribbean and Latin American traditions, including: Santeria, Palo, voodoo, and Espiritismo incorporate the use of elemental mercury in folk medicine and religious practice. Mercury is sold in most botanicas-stores specializing in herbal remedies and religious items used in these traditions. Its use, normally in small, enclosed spaces, combined with the fact that small amounts of mercury can remain for long periods of time, create the potential for very high direct exposures to individuals. Although these religious traditions have been well studied by anthropologists and sociologists, and many medical anthropologists have documented the use of potentially toxic remedies in folk medicine, little attention has been focused on the health implications of toxic substances used in religious rituals and spells.

Availability and extent of use
Several surveys have attempted to characterize mercury use in Latino/a and Afro Caribbean communities. Metallic mercury is available at botanicas in New York, New Jersey, and Pennsylvania, but botanica personnel often deny having mercury for sale when approached by outsiders to these religious and cultural traditions. Actions by public health authorities have driven the mercury trade underground in some locations. In a survey of New York City botanicas, 93% reported selling elemental mercury (about one to four capsules per day). A survey of 115 botanicas in 13 cities in the United States and Puerto Rico found that 99 sold mercury. Another survey of 203 Caribbean and Latin American adults in the New York City area found that 44% of Caribbean and 27% of Latin American respondents reported using mercury.

UsesMercury Necklace
Mercury is typically sold in capsules that contain, on average, about 8 or 9 g (0.3 oz.) mercury. The most common method of use reported by botanica personnel was to carry mercury on the person in a sealed pouch (49%) or in a pocket (32%) as an amulet; sprinkling mercury in the home was mentioned by 29%. Proprietors reported that family members, friends, spiritualists, and card readers recommend mercury to store patrons to bring luck in love, money, or health and to ward off evil. A survey of Latin American and Caribbean New York residents found that burning mercury in a candle, mixing it with perfume, and sprinkling it in the car were also frequently reported uses. Of 28 New York botanicas visited during another survey, 13 prescribed sprinkling mercury on the floor. Mercury poisoning has also been documented in Mexican-American infants fed mercury as a folk remedy for gastroenteritis. Medical anthropologist Robert Trotter identified the use of mercury, as well as lead oxides, for the treatment of empacho, a digestive illness.

As a result of these practices, living spaces may become contaminated with mercury. Removal of elemental mercury from floorboards and carpets is difficult, if not completely impractical. These mercury practices can be a direct source of contamination not only in the users, but also in their families, people living in adjacent apartments, and any future residents of the premises. The potential liability to present and future landlords is significant, because current and prospective homeowners may raise concerns about health risks related to prior mercury use on the premises. In addition, much of the mercury used in folk medicine and religious practice may be disposed of improperly. One survey found that 64% of mercury users in a study reported throwing mercury in the garbage, 27% flushed it down the toilet, and 9% threw it outdoors. Preliminary interviews with mercury users indicated a lack of knowledge about the inhalation pathway as the primary route of mercury exposure. People seem to know that mercury is toxic and avoid touching or eating it in most cases, but they do not seem to know about how quickly it turns into vapor (gas form) and the inhalation exposure risks associated with that. Several local and national education efforts have been undertaken in the past.

Community involvement, outreach, and education
Because botanicas represent a critical link to health care services in Latino/a and Afro Caribbean communities, it is important to recognize the role of botanicas in providing culturally congruent health interventions in their communities. Botanicas are the first place many turn for general health care services in Latino/a and Caribbean communities; any public health interventions to reduce mercury exposure must work with spiritualists, Santeros, and botanica proprietors. Working cooperatively with botanicas to promote effective substitutes and institute labeling for mercury is more likely to be effective than an adversarial enforcement approach that essentially criminalizes cultural practices. Outreach in Afro-Caribbean and Latino/a communities is a must. Such outreach and education will be most effective if they are coordinated with an effort to characterize the ways mercury use and its hazards are understood in the communities, so that communications can address any gaps in knowledge and provide the most important information to mercury users.

*Previous information taken from "Assessing Elemental Mercury Vapor Exposure from Cultural and Religious Practices," by Donna M. Riley, C. Alison Newby, Tomas O. Leal-Almeraz, Valerie M. Thomas-article published in Environmental Health Perspectives - Volume 109, Number 8, August 2001

July 4, 2001 Posted: 5:51 AM EDT

Thai diners told steer clear of 'toxic' shark fin
BANGKOK, Thailand - The health ministry in Thailand is urging diners to stay away from shark fin soup following reports that the increasingly popular delicacy may contain dangerously high levels of mercury.

On Tuesday a report by environmental pressure group Wild Aid said shark fins found on sale in Thailand contained levels of the heavy metal as much as 42 times the level considered safe for human consumption. Responding to the report, Deputy Public Health Minister Surapong Suebwonglee told Thai television Wednesday that officials were collecting samples of the soup from various restaurants and would be conducting tests over the coming days. He said that until safety tests had been completed diners should avoid eating the dish. Pressure groups have been calling for a halt to the growing trade in shark fins across Asia which they say is cruel, wasteful and having a devastating effect on the shark population. Shark fin soup has been growing in popularity across East Asia where, because of its high price, it is considered a prestigious dish to order at business occasions, weddings and other banquets.

Soaring demand
In Hong Kong, a world center for the shark fin trade, a single bowl of soup can cost more than US$100. To feed this demand environmentalists say millions of sharks are killed each year for the fin trade, most of them taken from waters in the Asia-Pacific region. Wild Aid says that between 1980 and 1997 trade in shark fins more than doubled to 7,000 tons annually. The majority of the sharks are pulled from the sea, have their fins hacked off, and are then thrown back into the water where -- unable to swim without their fins -- they drown. Environmentalists say sharks perform a vital function at the head of the food chain and dwindling shark populations will have a serious effect on the marine eco-system.

Bulked out
In conducting its survey Wild Aid said it had tested samples from 10 fins bought from three dealers in Bangkok's Chinatown. It said all contained dangerously high levels of mercury and were also pumped full of as yet unidentified chemicals. The report said that the need to bulk out fins in this way was a further sign that the shark numbers were decreasing. News that fins may contain dangerously high levels of toxins is being seen as adding further weight to environmentalists' campaigns to stem the trade. Already pressure from such groups had persuaded a number of Asian airlines to stop serving the soup to their business and first class passengers, and last year Taiwanese officials vowed to ban dishes made with shark fins from official banquets. In any case, campaigners say, the fins contain no nutritional value and have little themselves in the way of taste. They say that basically what diners are eating is cartilage, the same material that makes up fingernails or hair.

Shark fin

Even though they are considered a prestigious dish, shark fin consumption pose threat to consumers and to shark population.

*previous article taken from

What Is Special About Mercury

Even though mercury looks like something from outer space, it is a naturally occurring element that can be found on a periodic table. (Periodic symbol: Hg)

Special or Unique Properties of Mercury
So What?
  • Only metal that is liquid at room temperature.
  • Holds fascination for people of all ages. Special uses in several different cultures.
  • Easily evaporates into the air.
  • A blob of mercury sitting on the table will eventually disappear. The mercury vapors can be extremely dangerous to breathe.
  • Very dense, yet fluid. Density = 13.546 g/cm3(Density of water = 1.00 g/cm3)
  • Just a little bit weighs a lot, yet moves around easily. This is useful in certain medical procedures.
  • Good conductor of electricity.
  • Used in electrical "tilt" switches and other electrical devices.
  • Expands or contracts uniformly with changes in temperature.
  • Used in thermometers and thermostats.
  • Readily combines (amalgamates) with other metals.
  • Dentists use a combination of mercury and silver, called "amalgam," which is used to fill cavities in teeth.
  • Kills bacteria and fungi.
  • Previously used in pesticides, paints and on people to kill germs!

Table of elements


Activity 1 - Mercury I.Q.

Handout to students to test their mercury I.Q.

mercury banner

1. What is mercury?

a. A type of tree found in the rainforest
b. An element on the periodic table (symbol: Hg)
c. A liquid aliens like to put on their hamburgers

2. What is another common name for mercury?

a. Quicksilver
b. Space goo
c. There are no other names for mercury

3. What can mercury be found in?

a. Switches
b. Thermostats
c. Thermometers
d. All of the above

4. What animals are most likely to have elevated mercury levels in tissues?

a. Large fish
b. Snakes
c. Birds that live in a rainforest

5. Mercury is used in:

a. Dental fillings for cavities
b. Fluorescent lamps
c. Cars
d. All of the above

6. Mercury is mined today in what countries? (Mark all that apply)

a. U.S.
b. Spain
c. Mexico
d. Russia

7. Some states or local governments have passed bans on the sales of:

a. Mercury thermostats
b. Mercury thermometers
c. Fluorescent lights
d. All of the above

8. Mercury is the only known metal that is liquid at 72 degrees: True or False

9. Mercury can be very dangerous: True or False

Answer Sheet for activity 1

1. b 2. a 3. d 4. a 5. d
6. b 7. b 8. True 9. True  



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| Table of Contents |
| Introduction | Focus on Mercury | School Information | Household Information |
| Mercury in the Environment | Mercury in Our World and Community |

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Last revised: August 20, 2004