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Mercury
NM617 Fetotoxic Presentation
Elizabeth Cook and GeorgAnna Wiley
What’s the main way we get mercury in our bodies?
Coal-fired power plants remain the largest source of mercury pollution in America
(Sierra Club, 2008). Mercury is not a product of combustion. Rather, it is in coal
and is thus released in the exhaust systems when coal is burned (Sierra Club,
2006). Emitted mercury mixes with rain or snow falling back down into our water
and land, and then bacteria transform it into the most toxic form of mercury:
methylmercury. Fish consume the bacteria, then fish eat the contaminated fish,
and levels accumulate as the mercury builds up in the muscle (not just the fat and
skin!) (U.S. Geological Survey, 2002). Unfortunately, power plants emissions of
mercury are not regulated under the federal clean air standards (Jordan &
Nicholson, 2007). In fact, in spite of scientific evidence, the EPA has increased the
levels of mercury considered safe for humans (Jordan & Nicholson, 2007).
For the full story, visit
http://www.sierraclub.org/mercury/factsheets/2006-07_backgrounder.pdf
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Here’s a diagram:
(Sierra Club, 2008)
Where is mercury mainly found?
In the U.S., there are currently 12,000,000 acres of lakes and 400,000 miles river under advisory due to mercury pollution
(Jordan & Nicholson, 2007)
Known areas of increased risk:
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Wetlands
Dilute, low-pH lakes in Northeast and North-central United States
Great Lakes
Parts of the Florida Everglades
Newly flooded reservoirs
Coastal wetlands along Gulf of Mexico, Atlantic Ocean, and San Francisco Bay (USGS, 2002; Jordan &
Nicholson, 2007)
Areas near industrial/manufacturing sources:
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Power plants
Alkali and metal processing
Coal incineration plants
Gold mines
Natural sources:
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Volcanoes
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Geological deposits
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Ocean volatilization
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Some thermal springs
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Very rarely, a particular region with have an “outbreak” of mercury toxicity risks, such as Japan’s Minamata Bay in
1960 (Jordan & Nicholson, 2007; Diner, 2007)
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Atmospheric deposition remains the primary source (USGS, 2002)
What are the different types of
mercury?
Inorganic mercury (mercuric salts), found in:
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Antiseptics/disinfectants
Anti-syphilitic agents
Acetaldehyde production
Chemical laboratory work
Cosmetics (such as some illicit skin-lightening creams)
Electrical equipment
Embalming
Explosives
Fur hat processing
Fungicides
Ink manufacturing
Mercury vapor lamps
Mirror silvering
Perfumes
Photography
Some illegal skin-lightening cream
Spermicidal jellies
Tattooing inks
Taxidermy production
Vinyl chloride production
Wood preservatives (Diner, 2007; EPA, 2007; Jordan & Nicholson, 2007)
Elemental mercury (also inorganic, found in):
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Gold mines (used to extract gold, so also includes abandoned mines) (U.S. Geological Society, 2002).
Batteries (look for batteries that are mercury free – they are out there!)
Barometers
Bronzing
Calibration instruments
Chlor-alki production
Dental amalgams (ask your dentist – you can get fillings that do not have mercury, or the mercury can be
encapsulated)
Electroplating
Fingerprinting products
Fluorescent, neon, and mercury lamps (be careful when changing fluorescent bulbs!)
Infrared detectors
Jewelry industry
Paints
Paper pulp production
Photography
Silver and gold production
Semiconductor cells
Thermometers and Manometers (exposure occurs when they are broken and the vapor inhaled, however, in recent
years mercury is much less widely used in these) (Diner, 2007; EPA, 2007; Jordan & Nicholson, 2007)
Organic mercury:
Methylmercury is the organic form of mercury and is also the most toxic (U.S. Geological
Society, 2002). Other than our waters, it can be found in:
Vaccines containing thimerosal (anti-bacterial vaccine preservative), most notably in diphtheria-tetanuswhole cell pertussis (DTP), Haemophilus influenzae (HIB), hepatitis B vaccines, and seasonal influenza
vaccines. It is found in U.S. manufactured vaccines for preschool-aged children except for some flu
immunizations (Diner, 2007).
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Antiseptics
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Bactericidals
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Diapers
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Embalming agents
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Farming chemicals
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Fossil fuels
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Fungicides
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Germicides
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Histology products
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Insecticides
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Laundry products
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Pathology products
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Seed preservatives
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Wood preservatives
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Paper manufacturing – used as a catalyst for the formation of some chlorine compounds like paper pulp
bleaching, so is released into the air by factories and ending up in our water supply
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Some paints (especially anti-mildew paints made prior to 1990)
(OTIS, 2007; Diner, 2007)
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What does methylmercury do to adults at high doses?
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Methylmercury negatively impacts the immune system, nervous system (such as
coordination and the perception of touch, taste, and sight), as well as genetic and
enzyme systems (U.S. Geological Society, 2002). This form is the most toxic to
embryos/fetuses as they are 5 to 10 times more sensitive than adults to this
element (U.S. Geological Society, 2002). Compared to other forms, methylmercury
is easier to absorb and takes longer to eliminate (U.S. Geological Society, 2002).
In 2003, the American Association of Poison Control Centers' Toxic Exposure
Surveillance System reported mercury exposure in 3362 individuals with 44 having
moderate pathologies and 6 having major pathologies, but no deaths (Diner, 2007)
What about elemental mercury?
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This can be absorbed via skin, inhalation, ingestion, and injections (Diner, 2007)
When ingested, it can actually pass through the GI system without causing damage (U.S.
Geological Society, 2002).
Elemental mercury is a liquid at room temperature, but it also vaporizes at this temperature
and is easily inhaled, of which 80% is absorbed (Diner, 2007).
Occupation or activities where exposure is most likely
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Fishing, families of fishermen/women
Dentistry workers (mercury vapor exposure may be a concern but studies are
inconclusive) (Gardella & Hill, 2000)
Beauticians (skin lightening agents)
Painters
Anyone exposed to fungicides (including household use)
Paper mill workers
Occupations and activities that require contact or close proximity to the above items place
individuals at the greatest risk, particularly if over long periods of time (EPA, 2007).
What about mercury exposure during pregnancy?
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Methylmercury is the most common and most toxic form of mercury; it is commonly consumed in
fish from polluted waters (U.S. Geological Society, 2002).
Mercury can cause injury at any point in pregnancy (OTIS, 2007; Diner, 2007), so avoid all mercury
exposure if pregnant or may become pregnant within 12 months (Jordan & Nicholson, 2007)
1 in 5 US women has mercury levels above those recommended by the EPA; high enough to put a
baby at risk (Sierra Club, 2008).
The National Institute of Environmental Health Sciences estimated that the value of the repercussions
of mercury from coal burning power plants on fetuses at $1.3 billion each year (Sierra Club, 2006).
Mercury crosses the placenta easily and accumulates in embryonic and fetal tissues, particularly in the
brain and CNS, which are most vulnerable, thereby concentrating into levels higher than in the mother
(Gardella & Hill, 2000).
Effects may include:
Prematurity and preterm delivery (Xue, Holzman, Rahbar,
Trosko, & Fischer, 2006) Microcephaly
Cerebral palsy
Developmental delay
Mental retardation
Muscle weakness
Blindness
Seizures (OTIS, 2007; EPA, 2007)
Corrosive gastroenteritis
Acute tubular necrosis
Renal dysfunction (Diner, 2007)
How much is too much?
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Currently, adverse effects in children are suspected to stem from prenatal
exposures that resulted in maternal hair concentrations between 5 ppm for
subtle developmental changes to 10-20 ppm for clinically obvious changes
such as delayed walking (Dharan & Parviainen, 2006) or talking, cerebral
palsy, and mental retardation (Sierra Club, 2008).
The National Academy of Science-National Research Council
recommends a maintaining a level below 58 parts per billion of mercury in
cord blood or 12 parts per million of mercury in hair (Dharan & Parviainen,
2006).
What about our children?
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(that’s me and my daughter!)
Mercury is excreted in breastmilk (Diner, 2007).
Methyl mercury does not cause obvious structural malformations in humans, so the
devastating effects, which may not be obvious at birth, become evident only as indications
of abnormal neurologic development unfold (Gardella & Hill, 2000). Particularly
developmental and learning disabilities in small children (Sierra Club, 2008).
Children are very susceptible to mercury toxicity because their brains are growing rapidly
(Sierra Club, 2008). Children under age 6 should be protected from high mercury exposure
(Jordan & Nicholson, 2007)
EPA statistics show that 630,000 children at risk based on elevated mercury levels in
blood.
The Immunization Safety Review Committee of the IOM currently states that "the
evidence favors rejection of a causal relationship between thimerosal-containing vaccines
and autism." This appears to be supported by two recent cohort studies done in the UK to
assess a relationship between thimerosal use and autism. Further conclusive research needs
to be done, but perhaps the casual link between thimerosal and autism is not as strong as it
was once thought (Diner, 2007).
Can I ever eat fish again?!?
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Fish and shellfish contain high-quality protein and other essential
nutrients, are low in saturated fat, and contain omega-3 fatty acids (EPA,
2008).
Eating a variety of fish and shellfish can help keep our hearts healthy, and
contribute to children's proper growth and development (EPA). However,
nearly all fish and shellfish contain traces of mercury (EPA). In fact, fish is
the main method of mercury consumption (Jordan & Nicholson, 2007).
Risk is based on amount and/or frequency of consumption, and levels in
the fish and shellfish.
Some tips are:
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Small ocean fish (catfish, pollock, salmon), shellfish (king crab, shrimp), canned fish (light
tuna), fast food fish choices, and fish sticks usually fine
Canned albacore (white) and tuna steaks usually worse than canned light tuna
Completely avoid large, predatory species like tuna, shark, swordfish, king mackerel, and
tilefish (EPA, 2007). These fish contain methylmercury at concentrations that are 10-20
times higher than fish such as herring, cod, pollack, shrimp, or scallops
Mercury is also present in sushi (Sierra Club, 2008).
The EPA maintains documentation of mercury levels of major freshwater and saltwater
lakes and rivers, so you can check your local health department to investigate your are, or
visit: http://www.epa.gov/waterscience/fish/states.htm
Keep a wallet-sized fish guide in your wallet to be aware of what fish is higher risk, such
as those listed at: http://www.sierraclub.org/mercury/fishguide.pdf
Be aware of what fish are safe to eat, you can use this safe fish chart from the Children’s
Health Environmental Coalition (2004) from:
http://www.montereybayaquarium.org/cr/cr_seafoodwatch/sfw_recommendations.aspx
For the visual learners:
Tuna
Shark
Swordfish
Tilefish
King mackerel
How can I avoid consuming mercury in fish?
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Options for avoiding the mercury in mercury-contaminated fish are more limited than for
fish contaminated with PCBs, dioxins and other organic contaminants. Here are some tips:
Smaller or younger fish tend to have lower concentrations of mercury than older, larger
fish within the same water body.
Choose those that don’t live on the bottom of waterways, like lobsters.
Mercury concentrates in the muscle tissue of fish. So, unlike PCBs, dioxins and other
organic contaminants that concentrate in the skin and fat, mercury cannot be filleted or
cooked out of fish (U.S. Geological Society, 2002).
Choose wild-caught salmon, not farm-raised (or “ocean raised” as some companies now
disguise the farming under a new name) as they have less environmental toxins (CNN,
2005).
{a pic of farm raised salmon}
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Monitor local advisories about fish in your area if you fish. To find levels near you visit:
http://www.epa.gov/waterscience/fish/states.htm
Try not to eat the same fish or shellfish more than once a week (Children’s Health
Environmental Coalition, 2004).
Do you want to super-size that order?
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remember portion sizes? These are often large in the US, so remember for an adult, a
serving size is about 4 to 6 ounces (Children’s Health Environmental Coalition, 2004).
Three to 4 ounces is the size of the palm of your hand or a deck of cards.
Portions are less for children—about 2 to 3 ounces (or one tuna fish sandwich) (Children’s
Health Environmental Coalition, 2004).
Try to limit fish intake to 12 ounces a week of a variety of fish and shellfish that are lower
in mercury (EPA, 2007). If no advisory for your area, eat up to 6 ounces per week of fish
from local waters, but don't eat any other fish that week (Children’s Health Environmental
Coalition, 2004).
The EPA suggests women limiting fish intake to no more than 350 g/wk, or 12 ounces,
before and during pregnancy.
(a portion size of chicken, uncooked)
What if I eat more than the recommended
amount of fish and shellfish?
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The half-life of methylmercury is 44-80 days in humans (OTIS,
2007). Mercury is removed from your body in a few months (Sierra
Club, 2008).
One week's consumption of fish does not significantly affect the
level of methylmercury in the body. If you eat a lot of fish one
week, cut back for the next week or two. Overall, try to average the
recommended amount per week (EPA, 2007).
Let’s all get tested!
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non-profit study is underway by Sierra Club to
inexpensively detect levels of mercury in hair
samples: www.sierraclub.org/mercury
“An ounce of prevention is worth a pound of
cure”
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Working environments should have a mercury vapor level
below 0.01 mg/m3 (Dharan & Parviainen, 2006).
Be careful when handling fluorescent light bulbs. If
broken, they may release mercury (EPA, 2007).
If a woman reports exposure to mercury, her exposure can
be quantified clinically with hair testing (especially longterm or chronic exposure) or blood test (especially for
recent exposure) (OTIS, 2007).
Exercise your rights under the 1st
amendment
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The Bush administration has proposed a national plan to increase the allowable
levels of mercury by 3 times (Sierra Club, 2008). Therefore, change must occur at
the state level to initiate steps to clean up mercury and reduce allowable levels in
your neighborhood. Contact your governor about this issue, and get involved. To
find out how, check out: http://www.sierraclub.org/mercury/get_involved/
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To reduce mercury in our country, US residents need to petition state legislators
to support emission reductions and to install existing efficient technology to
capture mercury emissions from coal burning plants (Sierra Club, 2006).
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To email President Bush, contact your senator, state representative, or
legislator, find them at: http://www.usa.gov/Contact/Elected.shtml
Go on, send him an email!!!
again, that website is http://www.usa.gov/Contact/Elected.shtml
References
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Children’s Health Environmental Coalition. (2004). Safe Fish CHEC List
For children, teens and all women of childbearing age. Retrieved May 13, 2008,
from http://www.checnet.org/healthehouse/education/quicklistdetail.asp?Main_ID=716
CNN. (2005). Study: Farmed Salmon More Contaminated than Wild. Retrieved
May 13, 2008, from
http://edition.cnn.com/2004/HEALTH/01/08/salmon.pollution.ap/
Dharan, V. & Parviainen, K. (2006). Psychosocial and Environmental Pregnancy
Risks. Retrieved May 13, 2008, from
http://www.emedicine.com/med/topic3237.htm
Diner, B. (2007). Toxicity, Mercury. Retrieved May 10, 2008, from
http://www.emedicine.com/EMERG/topic813.htm
Environmental Protection Agency. (2008). What You Need to Know about Mercury
in Fish and Shellfish. Fish Advisories. Retrieved May 13, 2008, from
http://epa.gov/waterscience/fish/advice/#fastfood
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EPA. (2007). Mercury: Basic Information. Environmental Protection Agency.
Retrieved May 10, 2008, from http://www.epa.gov/mercury/about.htm
Gardella, J. & Hill, J. (2000). Environmental Toxins Associated With Recurrent
Pregnancy Loss. Semin Reprod Med 18(4):407-424.
Jordan, R. & Nicholson, T. (2007). Let’s Talk, NM617 Module 9. Hyden, KY:
Frontier School of Midwifery and Family Nursing.
Office of Citizen Services and Communications. (2008). Contact Elected Officials. Retrieved
May 13, 2008, from http://www.usa.gov/Contact/Elected.shtml
OTIS. (2007). Methylmercury and Pregnancy. Organization of Teratology Information
Specialists.
Sierra Club. (2006). The Clean Air Mercury Rule: Weak Control Standards for Coal-Fired
Power Plants. Retrieved May 13, 2008, from
http://www.sierraclub.org/mercury/factsheets/2006-07_backgrounder.pdf
Sierra Club. (2008). The Mercury Cycle. Retrieved May 13, 2008, from
http://www.sierraclub.org/mercury/mercury_cycle/
USGS. (2002). Mercury in the Environment: Fact Sheet 146-00. U.S. Geological
Survey. Retrieved May 10, 2008, from http://www.usgs.gov/themes/factsheet/14600/
Xue, F., Holzman, C., Rahbar, M., Trosko, K., & Fischer, L. (2006). Maternal Fish
Consumption, Mercury Levels, and Risk of Preterm Delivery. Environmental Health
Perspective, 115:42–47.
!!!!The End!!!!!