Public Health Statement for Mercury
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This Public Health Statement is the summary chapter from the Toxicological Profile for Mercury. It is one in a series of Public Health Statements about hazardous substances and their health effects. A shorter version, the ToxFAQsTM, is also available. This information is important because this substance may harm you. The effects of exposure to any hazardous substance depend on the dose, the duration, how you are exposed, personal traits and habits, and whether other chemicals are present. For more information, call the ATSDR Information Center at 1-800-232-4636.
This public health statement tells you about mercury and the effects of exposure.
The Environmental Protection Agency (EPA) identifies the most serious hazardous waste sites in the nation. These sites make up the National Priorities List (NPL) and are the sites targeted for long-term federal cleanup activities. Mercury has been found in at least 714 of the 1,467 current or former NPL sites. However, the total number of NPL sites evaluated for this substance is not known. As more sites are evaluated, the sites at which mercury is found may increase. This information is important because exposure to this substance may harm you and because these sites may be sources of exposure.
When a substance is released from a large area, such as an industrial plant, or from a container, such as a drum or bottle, it enters the environment. This release does not always lead to exposure. You are exposed to a substance only when you come in contact with it. You may be exposed by breathing, eating, or drinking the substance or by skin contact.
If you are exposed to mercury, many factors determine whether you'll be harmed. These factors include the dose (how much), the duration (how long), and how you come in contact with it. You must also consider the other chemicals to which you're exposed, as well as your age, sex, diet, family traits, lifestyle, and state of health.
What is mercury?
Mercury occurs naturally in the environment
and exists in several forms. These forms can be
organized under three headings: metallic mercury (also known
as elemental mercury), inorganic mercury, and organic mercury.
Metallic mercury is a shiny, silver-white metal that is a
liquid at room temperature. Metallic mercury is the
elemental or pure form of mercury (i.e., it is not combined
with other elements). Metallic mercury metal is the
familiar liquid metal used in thermometers and some electrical
switches. At room temperature, some of the metallic
mercury will evaporate and form mercury vapors. Mercury
vapors are colorless and odorless. The higher the temperature,
the more vapors will be released from liquid metallic mercury.
Some people who have breathed mercury vapors report a metallic
taste in their mouths. Metallic mercury has been found
at 714 hazardous waste sites nationwide.
Inorganic mercury compounds occur when
mercury combines with elements such as chlorine, sulfur, or
oxygen. These mercury compounds are also called mercury salts.
Most inorganic mercury compounds are white powders or crystals,
except for mercuric sulfide (also known as cinnabar) which
is red and turns black after exposure to light.
When mercury combines with carbon, the
compounds formed are called "organic" mercury compounds or
organomercurials. There is a potentially large number
of organic mercury compounds; however, by far the most common
organic mercury compound in the environment is methylmercury
(also known as monomethylmercury). In the past, an organic
mercury compound called phenylmercury was used in some commercial
products. Another organic mercury compound called
dimethylmercury is also used in small amounts as a reference
standard for some chemical tests. Dimethylmercury is
the only organic mercury compound that has been identified
at hazardous waste sites. It was only found in extremely
small amounts at two hazardous waste sites nationwide, but
it is very harmful to people and animals. Like the inorganic
mercury compounds, both methylmercury and phenylmercury exist
as "salts" (for example, methylmercuric chloride or phenylmercuric
acetate). When pure, most forms of methylmercury and
phenylmercury are white crystalline solids. Dimethylmercury,
however, is a colorless liquid.
Several forms of mercury occur naturally
in the environment. The most common natural forms of
mercury found in the environment are metallic mercury, mercuric
sulfide (cinnabar ore), mercuric chloride, and methylmercury.
Some microorganisms (bacteria and fungi) and natural processes
can change the mercury in the environment from one form to
another. The most common organic mercury compound that
microorganisms and natural processes generate from other forms
is methylmercury. Methylmercury is of particular concern
because it can build up in certain edible freshwater and saltwater
fish and marine mammals to levels that are many times greater
than levels in the surrounding water.
Mercury is mined as cinnabar ore, which
contains mercuric sulfide. The metallic form is refined
from mercuric sulfide ore by heating the ore to temperatures
above 1,000 degrees Fahrenheit. This vaporizes the mercury
in the ore, and the vapors are then captured and cooled to
form the liquid metal mercury. There are many different
uses for liquid metallic mercury. It is used in producing
of chlorine gas and caustic soda, and in extracting gold from
ore or articles that contain gold. It is also used in
thermometers, barometers, batteries, and electrical switches.
Silver-colored dental fillings typically contain about 50%
metallic mercury. Metallic mercury is still used in
some herbal or religious remedies in Latin America and Asia,
and in rituals or spiritual practices in some Latin American
and Caribbean religions such as Voodoo, Santeria, and Espiritismo.
These uses may pose a health risk from exposure to mercury
both for the user and for others who may be exposed to mercury
vapors in contaminated air.
Some inorganic mercury compounds are
used as fungicides. Inorganic salts of mercury, including
ammoniated mercuric chloride and mercuric iodide, have been
used in skin-lightening creams. Mercuric chloride is
a topical antiseptic or disinfectant agent. In the past,
mercurous chloride was widely used in medicinal products including
laxatives, worming medications, and teething powders.
It has since been replaced by safer and more effective agents.
Other chemicals containing mercury are still used as antibacterials.
These products include mercurochrome (contains a small amount
of mercury, 2%), and thimerosal and phenylmercuric nitrate,
which are used in small amounts as preservatives in some prescription
and over-the-counter medicines. Mercuric sulfide and
mercuric oxide may be used to color paints, and mercuric sulfide
is one of the red coloring agents used in tattoo dyes.
Methylmercury is produced primarily by
microorganisms (bacteria and fungi) in the environment, rather
than by human activity. Until the 1970s, methylmercury
and ethylmercury compounds were used to protect seed grains
from fungal infections. Once the adverse health effects
of methylmercury were known, the use of methymercury and ethylmercury
as fungicides was banned. Up until 1991, phenylmercuric
compounds were used as antifungal agents in both interior
and exterior paints, but this use was also banned because
mercury vapors were released from these paints.
What happens to mercury when it enters the
Mercury is a naturally occurring metal
found throughout the environment. Mercury enters the
environment as the result of the normal breakdown of minerals
in rocks and soil from exposure to wind and water, and from
volcanic activity. Mercury releases from natural sources
have remained relatively constant in recent history, resulting
in a steady rise in environmental mercury. Human activities
since the start of the industrial age (e.g., mining, burning
of fossil fuels) have resulted in additional release of mercury
to the environment. Estimates of the total annual mercury
releases that result from human activities range from one-third
to two-thirds of the total mercury releases. A major
uncertainty in these estimates is the amount of mercury that
is released from water and soils that were previously contaminated
by human activities as opposed to new natural releases.
The levels of mercury in the atmosphere (i.e., the air
you breathe in the general environment) are very, very low
and do not pose a health risk; however, the steady release
of mercury has resulted in current levels that are three to
six times higher than the estimated levels in the preindustrial
Approximately 80% of the mercury released
from human activities is elemental mercury released to the
air, primarily from fossil fuel combustion, mining, and smelting,
and from solid waste incineration. About 15% of the
total is released to the soil from fertilizers, fungicides,
and municipal solid waste (for example, from waste that contains
discarded batteries, electrical switches, or thermometers).
An additional 5% is released from industrial wastewater to
water in the environment.
With the exception of mercury ore deposits,
the amount of mercury that naturally exists in any one place
is usually very low. In contrast, the amount of mercury
that may be found in soil at a particular hazardous waste
site because of human activity can be high (over 200,000 times
natural levels). The mercury in air, water, and soil
at hazardous waste sites may come from both natural sources
and human activity.
Most of the mercury found in the environment
is in the form of metallic mercury and inorganic mercury compounds.
Metallic and inorganic mercury enters the air from mining
deposits of ores that contain mercury, from the emissions
of coal-fired power plants, from burning municipal and medical
waste, from the production of cement, and from uncontrolled
releases in factories that use mercury. Metallic mercury
is a liquid at room temperature, but some of the metal will
evaporate into the air and can be carried long distances.
In air, the mercury vapor can be changed into other forms
of mercury, and can be further transported to water or soil
in rain or snow. Inorganic mercury may also enter water
or soil from the weathering of rocks that contain mercury,
from factories or water treatment facilities that release
water contaminated with mercury, and from incineration of
municipal garbage that contains mercury (for example, in thermometers,
electrical switches, fluorescent light bulbs, or batteries
that have been thrown away). Inorganic or organic compounds
of mercury may be released to the water or soil if mercury-containing
fungicides are used.
Microorganisms (bacteria, phytoplankton
in the ocean, and fungi) convert inorganic mercury to methylmercury.
Methylmercury released from microorganisms can enter the water
or soil and remain there for a long time, particularly if
the methylmercury becomes attached to small particles in the
soil or water. Mercury usually stays on the surface
of sediments or soil and does not move through the soil to
underground water. If mercury enters the water in any
form, it is likely to settle to the bottom where it can remain
for a long time.
Mercury can enter and accumulate in the
food chain. The form of mercury that accumulates in
the food chain is methylmercury. Inorganic mercury does
not accumulate up the food chain to any extent. When
small fish eat the methylmercury in food, it goes into their
tissues. When larger fish eat smaller fish or other
organisms that contain methylmercury, most of the methylmercury
originally present in the small fish will then be stored in
the bodies of the larger fish. As a result, the larger
and older fish living in contaminated waters build up the
highest amounts of methylmercury in their bodies. Saltwater
fish (especially sharks and swordfish) that live a long time
and can grow to a very large size tend to have the highest
levels of mercury in their bodies. Plants (such as corn,
wheat, and peas) have very low levels of mercury, even if
grown in soils containing mercury at significantly higher
than background levels. Mushrooms, however, can accumulate
high levels if grown in contaminated soils.
How might I be exposed to mercury?
Because mercury occurs naturally in the
environment, everyone is exposed to very low levels of mercury
in air, water, and food. Between 10 and 20 nanograms
of mercury per cubic meter (ng/m3)
of air have been measured in urban outdoor air. These
levels are hundreds of times lower than levels still
considered to be "safe" to breathe. Background levels
in nonurban settings are even lower, generally about 6 ng/m3 or less. Mercury levels in surface water are generally
less than 5 parts of mercury per trillion parts of water (5
ppt, or 5 ng per liter of water), about a thousand times lower
than "safe" drinking water standards. Normal soil levels
range from 20 to 625 parts of mercury per billion parts of
soil (20–625 ppb; or 20,000– 625,000 ng per kilogram of soil).
A part per billion is one thousand times bigger than a part
A potential source of exposure to metallic
mercury for the general population is mercury released from
dental amalgam fillings. An amalgam is a mixture of
metals. The amalgam used in silver-colored dental fillings
contains approximately 50% metallic mercury, 35% silver, 9%
tin, 6% copper, and trace amounts of zinc. When the
amalgam is first mixed, it is a soft paste which is inserted
into the tooth surface. It hardens within 30 minutes.
Once the amalgam is hard, the mercury is bound within the
amalgam, but very small amounts are slowly released from the
surface of the filling due to corrosion or chewing or grinding
motions. Part of the mercury at the surface of the filling
may enter the air as mercury vapor or be dissolved in the
saliva. The total amount of mercury released from dental
amalgam depends upon the total number of fillings and surface
areas of each filling, the chewing and eating habits of the
person, and other chemical conditions in the mouth.
Estimates of the amount of mercury released from dental amalgams
range from 3 to 17 micrograms per day (μg/day). The
mercury from dental amalgam may contribute from 0 to more
than 75% of your total daily mercury exposure, depending on
the number of amalgam fillings you have, the amount of fish
consumed, the levels of mercury (mostly as methylmercury)
in those fish, and exposure from other less common sources
such as mercury spills, religious practices, or herbal remedies
that contain mercury. However, it should be kept in
mind that exposure to very small amounts of mercury, such
as that from dental amalgam fillings, does not necessarily
pose a health risk.
Whether the levels of exposure to mercury
vapor from dental amalgam are sufficiently high to cause adverse
health effects, and exactly what those effects are, continues
to be researched and debated by scientists and health officials.
U.S. government summaries on the effects of dental amalgam
conclude that there is no apparent health hazard to the general
population, but that further study is needed to determine
the possibility of more subtle behavioral or immune system
effects, and to determine the levels of exposure that may
lead to adverse effects in sensitive populations. Sensitive
populations may include pregnant women, children under the
age of 6 (especially up to the age of 3), people with impaired
kidney function, and people with hypersensitive immune responses
to metals. If you belong to this group, you should discuss
your medical condition with your dentist prior to any dental
restoration work. Removal of dental amalgams in people
who have no indication of adverse effects is not recommended
and can put the person at greater risk, if performed improperly.
Chelation therapy (used to remove metals from the body tissues)
itself presents some health risks, and should be considered
only when a licensed occupational or environmental health
physician determines it necessary to reduce immediate and
significant health risks due to high levels of mercury in
Some religions have practices that may
include the use of metallic mercury. Examples of these
religions include Santeria (a Cuban-based religion whose followers
worship both African deities and Catholic saints), Voodoo
(a Haitian-based set of beliefs and rituals), Palo Mayombe
(a secret form of ancestor worship practiced mainly in the
Caribbean), and Espiritismo (a spiritual belief system native
to Puerto Rico). Not all people who observe these religions
use mercury, but when mercury is used in religious, ethnic,
or ritualistic practices, exposure to mercury may occur both
at the time of the practice and afterwards from contaminated
indoor air. Metallic mercury is sold under the name
"azogue" (pronounced ah-SEW-gay) in stores called "botanicas."
Botanicas are common in Hispanic and Haitian communities,
where azogue may be sold as an herbal remedy or for spiritual
practices. The metallic mercury is often sold in capsules
or in glass containers. It may be placed in a sealed
pouch to be worn on a necklace or in a pocket, or it may be
sprinkled in the home or car. Some people may mix azogue
in bath water or perfume, or place azogue in devotional candles.
Because metallic mercury evaporates into the air, these practices
may put anyone breathing the air in the room at risk of exposure
to mercury. The longer people breathe the contaminated
air, the greater their risk will be. The use of metallic
mercury in a home or an apartment not only threatens the health
of the people who live there now, but also threatens the health
of future residents who may unknowingly be exposed to further
release of mercury vapors from contaminated floors or walls.
Metallic mercury is used in a variety
of household products and industrial items, including thermostats,
fluorescent light bulbs, barometers, glass thermometers, and
some blood pressure devices. The mercury in these devices
is contained in glass or metal, and generally does not pose
a risk unless the item is damaged or broken, and mercury vapors
are released. Spills of metallic mercury from broken
thermometers or damaged electrical switches in the home may
result in exposure to mercury vapors in indoor air. You must
be careful when you handle and dispose of all items in the
home that contain metallic mercury.
Very small amounts of metallic mercury
(for example, a few drops) can raise air concentrations of
mercury to levels that may be harmful to health. The
longer people breathe the contaminated air, the greater the
risk to their health. Metallic mercury and its vapors
are extremely difficult to remove from clothes, furniture,
carpet, floors, walls, and other such items. If these
items are not properly cleaned, the mercury can remain for
months or years, and continue to be a source of exposure.
It is possible for you to be exposed
to metallic mercury vapors from breathing contaminated air
around hazardous waste sites, waste incinerators, or power
plants that burn mercury-containing fuels (such as coal or
other fossil fuels), but most outdoor air is not likely to
contain levels that would be harmful. Exposure to mercury
compounds at hazardous waste sites is much more likely to
occur from handling contaminated soil (i.e., children playing
in or eating contaminated surface soil), drinking well-water,
or eating fish from contaminated waters near those sites.
Not all hazardous sites contain mercury, and not all waste
sites that do contain mercury have releases of mercury to
the air, water, or surface soils.
You can be exposed to mercury vapors
from the use of fungicides that contain mercury. Excess
use of these products may result in higher-than-average exposures.
You may also be exposed to mercury from swallowing or applying
to your skin outdated medicinal products (laxatives, worming
medications, and teething powders) that contain mercurous
chloride. Exposure may also occur from the improper
or excessive use of other chemicals containing mercury, such
as skin-lightening creams and some topical antiseptic or disinfectant
agents (mercurochrome and thimerosal).
Workers are mostly exposed from breathing
air that contains mercury vapors, but may also be exposed
to other inorganic mercury compounds in the workplace.
Occupations that have a greater potential for mercury exposure
include manufacturers of electrical equipment or automotive
parts that contain mercury, chemical processing plants that
use mercury, metal processing, construction where building
parts contain mercury (e.g., electrical switches, thermometers),
and the medical professions (medical, dental, or other health
services) where equipment may contain mercury (e.g., some
devices that measure blood pressure contain liquid mercury).
Dentists and their assistants may be exposed to metallic mercury
from breathing in mercury vapor released from amalgam fillings
and to a much lesser extent from skin contact with amalgam
restorations. Family members of workers who have been
exposed to mercury may also be exposed to mercury if the worker's
clothes are contaminated with mercury particles or liquid.
Some people may be exposed to higher
levels of mercury in the form of methylmercury if they have
a diet high in fish, shellfish, or marine mammals (whales,
seals, dolphins, and walruses) that come from mercury-contaminated
waters. Methylmercury accumulates up the food chain,
so that fish at the top of the food chain will have the most
mercury in their flesh. Of these fish, the largest (i.e.,
the oldest) fish will have the highest levels. The Food
and Drug Administration (FDA) estimates that most people are
exposed, on average, to about 50 ng of mercury per kilogram
of body weight per day (50 ng/kg/day) in the food they eat.
This is about 3.5 micrograms (μg) of mercury per day
for an adult of average weight. This level is not thought
to result in any harmful effects. A large part of this
mercury is in the form of methylmercury and probably comes
from eating fish. Commercial fish sold through interstate
commerce that are found to have levels of methylmercury above
an "action level" of 1 ppm (established by the FDA) cannot
be sold to the public. This level itself is below a
level associated with adverse effects. However, if you
fish in contaminated waters and eat the fish you catch, you
may be exposed to higher levels of mercury. Public health
advisories are issued by state and federal authorities for
local waters that are thought to be contaminated with mercury.
These advisories can help noncommercial (sport and subsistence)
fishermen and their families to avoid eating fish contaminated
with mercury. Foods other than fish that may contain
higher than average levels of mercury include wild game, such
as wild birds and mammals (bear) that eat large amounts of
contaminated fish. People in the most northern climates
may be exposed to high levels of mercury from eating meat
or fat from marine mammals including whales, dolphins, walruses,
and seals. These marine mammals are at or near the top
of their marine food chain. Plants contain very little methylmercury or other forms of mercury. Mushrooms grown
in mercury-contaminated soil may contain levels of mercury
that could pose some risk to health, if large amounts were
How can mercury enter and leave my body?
A person can be exposed to mercury from
breathing in contaminated air, from swallowing or eating contaminated
water or food, or from having skin contact with mercury.
Not all forms of mercury easily enter your body, even if they
come in contact with it; so it is important to know which
form of mercury you have been exposed to, and by which route
(air, food, or skin).
When you swallow small amounts of metallic
mercury, for example, from a broken oral thermometer, virtually
none (less than 0.01%) of the mercury will enter your body
through the stomach or intestines, unless they are diseased.
Even when a larger amount of metal mercury (a half of a tablespoon,
about 204 grams) was swallowed by one person, very little
entered the body. When you breathe in mercury vapors,
however, most (about 80%) of the mercury enters your bloodstream
directly from your lungs, and then rapidly goes to other parts
of your body, including the brain and kidneys. Once in your
body, metallic mercury can stay for weeks or months.
When metallic mercury enters the brain, it is readily converted
to an inorganic form and is "trapped" in the brain for a long
time. Metallic mercury in the blood of a pregnant
woman can enter her developing child. Most of the metallic
mercury will accumulate in your kidneys, but some metallic
mercury can also accumulate in the brain. Most of the
metallic mercury absorbed into the body eventually leaves
in the urine and feces, while smaller amounts leave the body
in the exhaled breath.
Inorganic mercury compounds like mercurous
chloride and mercuric chloride are white powders and do not
generally vaporize at room temperatures like elemental mercury
will. If they are inhaled, they are not expected to
enter your body as easily as inhaled metallic mercury vapor.
When inorganic mercury compounds are swallowed, generally
less than 10% is absorbed through the intestinal tract; however,
up to 40% may enter the body through the stomach and intestines
in some instances. Some inorganic mercury can enter
your body through the skin, but only a small amount will pass
through your skin compared to the amount that gets into your
body from swallowing inorganic mercury.
Once inorganic mercury enters the body
and gets into the bloodstream, it moves to many different
tissues. Inorganic mercury leaves your body in the urine
or feces over a period of several weeks or months. A
small amount of the inorganic mercury can be changed in your
body to metallic mercury and leave in the breath as a mercury
vapor. Inorganic mercury accumulates mostly in the kidneys
and does not enter the brain as easily as metallic mercury.
Inorganic mercury compounds also do not move as easily from
the blood of a pregnant woman to her developing child.
In a nursing woman, some of the inorganic mercury in her body
will pass into her breast milk.
Methylmercury is the form of mercury
most easily absorbed through the gastrointestinal tract (about
95% absorbed). After you eat fish or other foods that are
contaminated with methylmercury, the methylmercury enters
your bloodstream easily and goes rapidly to other parts of
your body. Only small amounts of methylmercury enter
the bloodstream directly through the skin, but other forms
of organic mercury (in particular dimethylmercury) can rapidly
enter the body through the skin. Organic mercury compounds
may evaporate slowly at room temperature and may enter your
body easily if you breathe in the vapors. Once organic
mercury is in the bloodstream, it moves easily to most tissues
and readily enters the brain. Methylmercury that is
in the blood of a pregnant woman will easily move into the
blood of the developing child and then into the child's brain
and other tissues. Like metallic mercury, methylmercury
can be changed by your body to inorganic mercury. When
this happens in the brain, the mercury can remain there for
a long time. When methylmercury does leave your body
after you have been exposed, it leaves slowly over a period
of several months, mostly as inorganic mercury in the feces.
As with inorganic mercury, some of the methylmercury in a
nursing woman's body will pass into her breast milk.
How can mercury affect my health?
The nervous system is very sensitive
to mercury. In poisoning incidents that occurred in
other countries, some people who ate fish contaminated with
large amounts of methylmercury or seed grains treated with
methylmercury or other organic mercury compounds developed
permanent damage to the brain and kidneys. Permanent
damage to the brain has also been shown to occur from exposure
to sufficiently high levels of metallic mercury. Whether
exposure to inorganic mercury results in brain or nerve damage
is not as certain, since it does not easily pass from the
blood into the brain.
Metallic mercury vapors or organic mercury
may affect many different areas of the brain and their associated
functions, resulting in a variety of symptoms. These
include personality changes (irritability, shyness, nervousness),
tremors, changes in vision (constriction (or narrowing) of
the visual field), deafness, muscle incoordination, loss of
sensation, and difficulties with memory.
Different forms of mercury have different
effects on the nervous system, because they do not all move
through the body in the same way. When metallic mercury
vapors are inhaled, they readily enter the bloodstream and
are carried throughout the body and can move into the brain.
Breathing in or swallowing large amounts of methylmercury
also results in some of the mercury moving into the brain
and affecting the nervous system. Inorganic mercury
salts, such as mercuric chloride, do not enter the brain as
readily as methylmercury or metallic mercury vapor.
The kidneys are also sensitive to the
effects of mercury, because mercury accumulates in the kidneys
and causes higher exposures to these tissues, and thus more
damage. All forms of mercury can cause kidney damage
if large enough amounts enter the body. If the damage
caused by the mercury is not too great, the kidneys are likely
to recover once the body clears itself of the contamination.
Short-term exposure (hours) to high levels
of metallic mercury vapor in the air can damage the lining
of the mouth and irritate the lungs and airways, causing tightness
of the chest, a burning sensation in the lungs, and coughing.
Other effects from exposure to mercury vapor include nausea,
vomiting, diarrhea, increases in blood pressure or heart rate,
skin rashes, and eye irritation. Damage to the lining
of the mouth and lungs can also occur from exposure to lower
levels of mercury vapor over longer periods (for example,
in some occupations where workers were exposed to mercury
for many years). Levels of metallic mercury in workplace
air are generally much greater than the levels normally encountered
by the general population. Current levels of mercury
in workplace air are low, due to increased awareness of mercury's
toxic effects. Because of the reduction in the allowable
amount of mercury in workplace air, fewer workers are expected
to have symptoms of mercury toxicity. Most studies of
humans who breathed metallic mercury for a long time indicate
that mercury from this type of exposure does not affect the
ability to have children. Studies in workers exposed
to metallic mercury vapors have also not shown any mercury-related
increase in cancer. Skin contact with metallic mercury
has been shown to cause an allergic reaction (skin rashes)
in some people.
In addition to effects on the kidneys,
inorganic mercury can damage the stomach and intestines, producing
symptoms of nausea, diarrhea, or severe ulcers if swallowed
in large amounts. Effects on the heart have also been
observed in children after they accidentally swallowed mercuric
chloride. Symptoms included rapid heart rate and increased
blood pressure. There is little information on the effects
in humans from long-term, low-level exposure to inorganic
To protect the public from the harmful
effects of toxic chemicals and to find ways to treat people
who have been harmed, scientists use many tests.
One way to see if a chemical will hurt
people is to learn how the chemical is absorbed, used, and
released by the body; for some chemicals, animal testing may
be necessary. Animal testing may also be used to identify
health effects such as cancer or birth defects. Without
laboratory animals, scientists would lose a basic method to
get information needed to make wise decisions to protect public
health. Scientists have the responsibility to treat
research animals with care and compassion. Laws today
protect the welfare of research animals, and scientists must
comply with strict animal care guidelines.
Studies using animals indicate that long-term
oral exposure to inorganic mercury salts causes kidney damage,
effects on blood pressure and heart rate, and effects on the
stomach. Study results also suggest that reactions involving
the immune system may occur in sensitive populations after
swallowing inorganic mercury salts. Some animal studies
report that nervous system damage occurs after long-term exposure
to high levels of inorganic mercury. Short-term, high-level
exposure of laboratory animals to inorganic mercury has been
shown to affect the developing fetus and may cause termination
of the pregnancy.
Animals exposed orally to long-term,
high levels of methylmercury or phenylmercury in laboratory
studies experienced damage to the kidneys, stomach, and large
intestine; changes in blood pressure and heart rate; adverse
effects on the developing fetus, sperm, and male reproductive
organs; and increases in the number of spontaneous abortions
and stillbirths. Adverse effects on the nervous system
of animals occur at lower doses than do harmful effects to
most other systems of the body. This difference indicates
that the nervous system is more sensitive to methylmercury
toxicity than are other organs in the body. Animal studies
also provide evidence of damage to the nervous system from
exposure to methylmercury during development, and evidence
suggests that the effects worsen with age, even after the
Some rat and mice strains that are susceptible
to autoimmune responses develop kidney damage as a result
of an immune response when exposed to relatively low levels
of mercury vapor or mercury chloride.
Animals given inorganic mercury salts
by mouth for most of their lifetime had increases in some
kinds of tumors at the highest dose tested. Rats and
mice that received organic mercury (methylmercury or
phenylmercury) in their drinking water or feed for most of
their lives had an increased incidence of cancer of the kidney,
but this affected only the males that received the highest
amount of mercury given (not the females). Since the
high doses caused severe damage to the kidneys prior to the
cancer, these animal studies provide only limited information
about whether mercury causes cancer in humans. As a
result, the Department of Health and Human Services (DHHS)
and the International Agency for Research on Cancer (IARC)
have not classified mercury as to its human carcinogenicity.
The Environmental Protection Agency has determined that mercury
chloride and methylmercury are possible human carcinogens.
How can mercury affect children?
This section discusses potential health
effects from exposures during the period from conception to
maturity at 18 years of age in humans. Potential effects
on children resulting from exposures of the parents are also
Children are at risk of being exposed
to metallic mercury that is not safely contained, to mercury
that may be brought home on work clothes or tools, or to methylmercury-contaminated
foods. Methylmercury eaten or swallowed by a pregnant
woman or metallic mercury that enters her body from breathing
contaminated air can also pass into the developing child.
Inorganic mercury and methylmercury can also pass from a mother's
body into breast milk and into a nursing infant. The
amount of mercury in the milk will vary, depending on the
degree of exposure and the amount of mercury that enter the
nursing woman's body. There are significant benefits
to breast feeding, so any concern that a nursing woman may
have about mercury levels in her breast milk should be discussed
with her doctor. Methylmercury can also accumulate in
an unborn baby's blood to a concentration higher than the
concentration in the mother.
For similar exposure routes and forms
of mercury, the harmful health effects seen in children are
similar to the effects seen in adults. High exposure
to mercury vapor causes lung, stomach, and intestinal damage
and death due to respiratory failure in severe cases.
These effects are similar to those seen in adult groups exposed
to inhaled metallic mercury vapors at work.
Children who had been exposed to excessive
amounts of mercurous chloride tablets for worms or mercurous
chloride-containing powders for teething discomfort had increased
heart rates and elevated blood pressure. Abnormal heart
rhythms were also seen in children who had eaten grains contaminated
with very high levels of methylmercury.
Other symptoms of poisonings in children
who were treated with mercurous chloride for constipation,
worms, or teething discomfort included swollen red gums, excessive
salivation, weight loss, diarrhea and/or abdominal pain, and
muscle twitching or cramping in the legs and/or arms.
Kidney damage is very common after exposure to toxic levels
of inorganic mercury. Metallic mercury or methylmercury
that enters the body can also be converted to inorganic mercury
and result in kidney damage.
Children who breathe metallic/elemental
mercury vapors, eat foods or other substances containing phenylmercury
or inorganic mercury salts, or use mercury-containing skin
ointments for an extended period may develop a disorder
known as acrodynia, or pink disease. Acrodynia can result
in severe leg cramps; irritability; and abnormal redness of
the skin, followed by peeling of the hands, nose, and soles
of the feet. Itching, swelling, fever, fast heart rate,
elevated blood pressure, excessive salivation or sweating,
rashes, fretfulness, sleeplessness, and/or weakness may also
be present. It was once believed that this syndrome
occurred only in children, but recent reported cases in teenagers
and adults have shown that they can also develop acrodynia.
In critical periods of development before
they are born, and in the early months after birth, children
and fetuses are particularly sensitive to the harmful effects
of metallic mercury and methylmercury on the nervous system.
Harmful developmental effects may occur when a pregnant woman
is exposed to metallic mercury and some of the mercury is
transferred into her developing child. Thus, women who
are normally exposed to mercury vapors in the workplace (such
as those working in thermometer/barometer or fluorescent
light manufacturing or the chlor-alkali industry) should take
measures to avoid mercury vapor exposures during pregnancy.
Exposures to mercury vapors are relatively rare outside of
the workplace, unless metallic mercury is present in the home.
As with mercury vapors, exposure to methylmercury
is more dangerous for young children than for adults, because
more methylmercury easily passes into the developing brain
of young children and may interfere with the development process.
Methylmercury is the form of mercury
most commonly associated with a risk for developmental effects.
Exposure can come from foods contaminated with mercury on
the surface (for example, from seed grain treated with methylmercury
to kill fungus) or from foods that contain toxic levels of
methylmercury (as in some fish, wild game, and marine mammals).
Mothers who are exposed to methylmercury and breast-feed their
infant may also expose the child through the milk. The
effects on the infant may be subtle or more pronounced, depending
on the amount to which the fetus or young child was exposed.
In cases in which the exposure was relatively small, some
effects might not be apparent, such as small decreases in
IQ or effects on the brain that may only be determined by
the use of very sensitive neuropsychological testing.
In instances in which the exposure is great, the effects may
be more serious. In some such cases of mercury exposure
involving serious exposure to the developing fetus, the effects
are delayed. In such cases, the infant may be
born apparently normal, but later show effects that may range
from the infant being slower to reach developmental milestones,
such as the age of first walking and talking, to more severe
effects including brain damage with mental retardation, incoordination,
and inability to move. Other severe effects observed
in children whose mothers were exposed to very toxic levels
of mercury during pregnancy include eventual blindness, involuntary
muscle contractions and seizures, muscle weakness, and inability
to speak. It is important to remember, however, that
the severity of these effects depends upon the level of mercury
exposure and the length of exposure. The very severe
effects just mentioned were reported in large-scale poisoning
instances in which pregnant and nursing women were exposed
to extremely high levels of methylmercury in contaminated
grain used to make bread (in Iraq) or seafood (in Japan) sold
to the general population.
Researchers are currently studying the
potential for less serious developmental effects, including
effects on a child's behavior and ability to learn, think,
and solve problems that may result from eating lower levels
of methylmercury in foods. A main source of exposure
to methylmercury for the pregnant woman and the young child
is from eating fish. Most fish purchased in the market
in the United States do not have mercury levels that pose
a risk to anyone, including pregnant women. Since mercury
accumulates in the muscles of fish, larger fish that feed
on smaller fish and live for long periods usually have larger
concentrations of methylmercury than fish that feed on plants.
For example, shark and swordfish normally contain the highest
levels of mercury out of all ocean fish. Scientists have an
ongoing debate about the value of fish in the diet versus
any risk from increased exposure of pregnant women to methylmercury
that may be in the fish. The safety of most fish sold
commercially in the United States is regulated by the
FDA. These fish pose no health risk to those who purchase
and eat them. Only fish or wildlife containing relatively
high levels of methylmercury are of concern.
How can families reduce the risk of
exposure to mercury?
If your doctor finds that you have been
exposed to significant amounts of mercury, ask whether your
children might also be exposed. Your doctor might need
to ask your state health department to investigate.
Children may be exposed to metallic mercury
if they play with it. Metallic mercury is a heavy, shiny,
silver liquid. When metallic mercury is spilled, it
forms little balls or beads. Children are sometimes
exposed to metallic mercury when they find it in abandoned
warehouses or closed factories, and then play with it or pass
it around to friends. Children have also taken metallic
mercury from school chemistry and physics labs. Broken
thermometers and some electrical switches are other sources
of metallic mercury. Sometimes children find containers
of metallic mercury that were improperly disposed of, or adults
may bring home metallic mercury from work, not knowing that
it is dangerous.
To protect your children from metallic
mercury, teach them not to play with shiny, silver liquids.
Schoolteachers (particularly science teachers) and school
staff need to know about students' fascination with metallic
mercury. Teachers and school staff should teach children
about the dangers of getting sick from playing with mercury,
and they should keep metallic mercury in a safe and secured
area (such as a closed container in a locked storage room)
so that children do not have access to it without the supervision
of a teacher. Metallic mercury evaporates slowly, and
if it is not stored in a closed container, children may breathe
toxic mercury vapors.
In the past, mercurous chloride was widely
used in medicinal products such as laxatives, worming medications,
and teething powders. These older medicines should be
properly disposed of and replaced with safer and more effective
medicines. Other chemicals containing mercury, such
as mercurochrome and thimerosal (sold as Merthiolate and other
brands), are still used as antiseptics or as preservatives
in eye drops, eye ointments, nasal sprays, and vaccines.
Some skin-lightening creams contain ammoniated mercuric chloride
and mercuric iodide. These and all other mercury-containing
medicines should be kept safely out of the reach of children
to prevent an accidental poisoning. Nonmedicinal products,
including some fungicides that contain mercury compounds and
paints that contain mercuric sulfide or mercuric oxide, should
also be safely stored out of the reach of children.
You should check to see if any medicines
or herbal remedies that you or your child use contain mercury.
Some traditional Chinese and Hispanic remedies for stomach
disorders (for example, herbal balls) contain mercury, and
if you give these remedies to your children, you may harm
them. If you are pregnant or nursing a baby and you
use mercury-containing ethnic or herbal remedies, you
could pass some of the mercury to your unborn child or nursing
If you use metallic mercury or azogue
in religious practices, you may expose your children or unborn
child to mercury or contaminate your home. Such practices
in which mercury containing substances have traditionally
been used include Santeria (a Cuban-based religion whose followers
worship both African deities and Catholic saints), Voodoo
(a Haitian-based set of beliefs and rituals), Palo Mayombe
(a secret form of ancestor worship practiced mainly in the
Caribbean), or Espiritismo (a spiritual belief system native
to Puerto Rico).
Metallic mercury is used in a variety
of household products and industrial items, including thermostats,
fluorescent light bulbs, barometers, glass thermometers, and
some blood pressure measuring devices. You must be careful
when you handle and dispose of all items in the home that
contain metallic mercury.
If small amounts of mercury are spilled,
be very careful cleaning it up. Do not try to vacuum
spilled metallic mercury. Using a vacuum cleaner to clean
up the mercury causes the mercury to evaporate into the air,
creating greater health risks. Trying to vacuum spilled
metallic mercury also contaminates the vacuum cleaner.
Also, take care not to step on the mercury and track it into
other areas of the home. Metallic mercury vapors are
very toxic and have no odor. Do not remain unnecessarily in
that room, and try not to let metallic mercury contact your
eyes, skin, or clothing. If you think you have been
exposed directly to metallic mercury, wash yourself thoroughly
and discard contaminated clothing by placing them in a sealed
plastic bag. Perhaps the most important thing to remember
if you break a household thermometer is do not panic.
The amount of mercury contained in an oral thermometer is
small and does not present an immediate threat to human health.
However, if it is not properly cleaned up and disposed of,
it may present a health risk over time, particularly to infants,
toddlers, and pregnant women.
If a thermometer breaks on a counter
top or uncarpeted floor, remove children from the area.
Mercury is not absorbent, so do not try to wipe or blot it
up with a cloth or paper towel; that will only spread the
mercury and break it up into smaller beads, making it more
difficult to find and remove. Instead, clean up the
beads of metallic mercury by using one sheet of paper to carefully
roll them onto a second sheet of paper, or by sucking very
small beads of mercury into an eye dropper. After picking
up the metallic mercury in this manner, put it into a plastic
bag or airtight container. The paper and eye dropper
should also be bagged in a zip-lock plastic container.
All plastic bags used in the cleanup should then be taken
outside of the house or apartment and disposed of properly,
according to instructions provided by your local health department
or environmental officials. Try to ventilate the room
with outside air, and close the room off from the rest of
the home. Use fans (that direct the air to the outside
and away from the inside of the house) for a minimum of one
hour to speed the ventilation.
If a thermometer breaks and the liquid/metallic
mercury spills onto a carpeted floor, try to collect the mercury
beads in the manner described in the above paragraph.
Depending on the cut or pile of the carpeting, however, it
may not be possible to collect all of the spilled mercury.
Regardless, do not vacuum. Instead, call your local
(county, city, or state) health department and tell them of
your situation. (You may also call the Agency for Toxic Substances
and Disease Registry [ATSDR] toll-free at 1-888-42-ATSDR [1-888-422-8737]
to obtain additional guidance, if local assistance cannot
If larger amounts of metallic mercury
are found (for example, a jar of liquid mercury), it should
be contained in an airtight container, and you should call
your local health department for instructions on how to safely
dispose of it. If the mercury is in an open container
or the container does not have a lid, place a piece of plastic
wrap around the top of the container to prevent vapors from
escaping; then wash your hands thoroughly. If a larger
amount is spilled, leave the area and contact your local health
department and fire department. Do not simply throw
metallic mercury away, but instead seek professional help.
ATSDR and EPA strongly recommend against
the use of metallic (liquid) mercury that is not properly
enclosed in glass, as it is in thermometers. This form
of mercury should not be used or stored in homes, automobiles,
day-care centers, schools, offices, or other public buildings.
If you notice a child with metallic mercury on his or her
clothing, skin, or hair, call the fire department and let
them know that the child needs to be decontaminated.
Metallic or inorganic mercury can be
carried into the home from a workers' contaminated clothing
and shoes. Increased exposure to mercury has been reported
in children of workers who are exposed to mercury at work,
and increased levels of mercury were measured in places where
work clothes were stored and in some washing machines.
The children most likely to be exposed to risky levels of
mercury are those whose parents work in facilities that use
mercury (for example, a scientific glassware manufacturing
plant or a chlor-alkali chemical plant), but where no protective
uniforms or footgear are used. In some reported cases
in which children were exposed in this way, protective clothing
was used in the workplace by the parent, but work gloves,
clothes, and boots, which were contaminated with mercury,
were taken home, thus exposing family members. If you
have questions or concerns about exposure to mercury at work,
you have a right to obtain information from your employer
about your safety and health on the job without fear of punishment.
The Occupational Safety and Health Administration (OSHA) requires
employers to provide Material Safety Data Sheets (MSDSs) for
many of the chemicals used at the workplace. Information
on these sheets should include chemical names and hazardous
ingredients, important properties (such as fire and explosion
data), potential health effects, how you get the chemical(s)
in your body, how to properly handle the materials, and what
to do in an emergency. Your occupational health and
safety officer at work can and should tell you whether chemicals
you work with are dangerous and likely to be carried home
on your clothes, body, or tools, and whether you should be
showering and changing clothes before you leave work, storing
your street clothes in a separate area of the workplace, or
laundering your work clothes at home separately from other
Your employer is legally responsible
for providing a safe workplace and should freely answer your
questions about hazardous chemicals. Your OSHA-approved
state occupational safety and health program or OSHA can also
answer any further questions you might have, and help your
employer identify and correct problems with hazardous substances.
If you would like to make a formal complaint about health
hazards in your workplace, your OSHA-approved state occupational
safety and health program or OSHA office will listen to your
complaint and inspect your workplace when necessary.
One way in which people are routinely
exposed to extremely small amounts of mercury is through the
gradual (but extremely slow) wearing-away process
of dental amalgam fillings, which contain approximately 50%
mercury. The amount of mercury to which a person might
be exposed from dental amalgams would depend on the number
of amalgams present and other factors. The Centers for
Disease Control and Prevention (CDC) has determined that dental
amalgam fillings do not pose a health risk, although they
do account for some mercury exposure to those having such
fillings. People who frequently grind their teeth or
often chew gum can add to the small amount of mercury normally
released from those fillings over time. If you
are pregnant, the decision of whether to have dental amalgam
or a non-mercury material used for fillings, or whether existing
amalgam fillings should be repaired or replaced during pregnancy,
should be made in consultation with your dentist. The
practice of having all your dental amalgam fillings replaced
with non-mercury filling materials just to remove the possibility
of mercury exposure is not recommended by ATSDR. In
fact, the removal of the mercury amalgam fillings would actually
expose the patient to a greater amount of mercury for a while.
Other sources of mercury may increase your overall exposure,
such as the amount of fish consumed per week, especially if
caught in local waters contaminated with mercury or
of certain species known to be higher in mercury content (shark
and swordfish), or an exposure to mercury from a nearby hazardous
waste site or incinerator.
You or your children may be exposed to
methylmercury when eating certain types of fish caught from
contaminated waters, or when eating certain types of wildlife
from mercury contaminated areas. Most states, Native
American tribes, and U.S. Territories have issued fish and/or
wildlife advisories to warn people about methylmercury contaminated
fish and/or wildlife. Most of the methylmercury advisories
relate to specific types of freshwater or saltwater fish or
shellfish, or freshwater turtles. Each state, Native
American tribe, or U.S. Territory sets its own criteria for
issuing fish and wildlife advisories. A fish or wildlife
advisory will specify which bodies of water or hunting areas
have restrictions. The advisory will tell you what types
and sizes of fish or game are of concern. The advisory
may completely ban eating fish or tell you to limit your meals
of a certain type of fish. For example, an advisory
may tell you to eat a certain type of fish no more than once
a month; or an advisory may tell you to eat only certain parts
of fish or game, or how to prepare it to decrease your exposure
to methylmercury. The fish or wildlife advisory may
be stricter to protect pregnant women, nursing women, and
young children. To reduce your children's exposure to
methylmercury, you should follow the instructions recommended
in the fish or wildlife advisories. Information on Fish
and Wildlife Advisories in your state is available from your
state public health or natural resources department.
Signs may also be posted in certain fishing and hunting areas
with information about contaminated fish or wildlife.
FDA currently advises that pregnant women
and women of childbearing age who may become pregnant limit
their consumption of shark and swordfish to no more that one
meal per month. This advice is given because methylmercury
levels are relatively high in these fish species.
Women of childbearing age are included in this advice because
dietary practices immediately before the pregnancy could have
a direct bearing on fetal exposure during pregnancy, particularly
during the earlier months of pregnancy.
FDA further advises that persons other
than pregnant women and women of childbearing age in the general
population limit their regular consumption of shark and swordfish
(which typically contains methylmercury around 1 ppm) to about
7 ounces per week (about one serving) to stay below the acceptable
daily intake for methylmercury. For fish species with
methylmercury levels averaging 0.5 ppm, regular consumption
should be limited to 14 ounces per week. Recreational
and subsistence fishers who eat larger amounts of fish than
the general population and routinely fish the same waterbodies
may have a higher exposure to methylmercury if these waters
are contaminated. People who consume greater than 100
grams of fish (approximately 3.5 ounces) every day are considered
high-end consumers. This is over 10 times more than
the amount of fish consumed by members of the general population
(6.5 g/day). No consumption advice is necessary for
the top ten seafood species that make up about 80% of the
seafood sold in the United States: canned tuna, shrimp,
pollock, salmon, cod, catfish, clams, flatfish, crabs, and
scallops. The methylmercury in these species is generally
less than 0.2 ppm, and few people eat more than the suggested
weekly limit of fish (i.e., 2.2 pounds).
If you are concerned about a mercury
exposure or think that you or your child are experiencing
the adverse effects of mercury, you should consult with a
doctor or public health official who is familiar with the
health effects of mercury.
Is there a medical test to determine
whether I have been exposed to mercury?
There are reliable and accurate ways
to measure mercury levels in the body. These tests all
involve taking blood, urine, or hair samples, and must be
performed in a doctor's office or in a health clinic.
Nursing women may have their breast milk tested for mercury
levels, if any of the other samples tested are found to contain
significant amounts of mercury. Most of these tests,
however, do not determine the form of mercury to which you
were exposed. Mercury levels found in blood, urine,
breast milk, or hair may be used to determine if adverse health
effects are likely to occur. Mercury in urine is used
to test for exposure to metallic mercury vapor and to inorganic
forms of mercury. Measurement of mercury in whole
blood or scalp hair is used to monitor exposure to methylmercury.
Urine is not useful for determining whether exposure has occurred
to methylmercury. Levels found in blood, urine, and
hair may be used together to predict possible health effects
that may be caused by the different forms of mercury.
Blood and urine levels are used as markers
to determine whether someone has been exposed to mercury.
They are used to determine whether exposure to mercury has
occurred and to give a rough idea of the extent of exposure,
but they do not tell exactly how much exposure has occurred.
Except for methylmercury exposures, blood is considered useful
if samples are taken within a few days of exposure.
This is because most forms of mercury in the blood decrease
by one-half every three days if exposure has been stopped.
Thus, mercury levels in the blood provide more useful information
after recent exposures than after long-term exposures.
Several months after an exposure, mercury levels in the blood
and urine are much lower. Hair, which is considered
useful only for exposures to methylmercury, can be used to
show exposures that occurred many months ago, or even more
than a year ago if the hair is long enough and careful testing
methods are used. After short-term exposures to metallic
mercury, mercury vapor can be detected in the breath, but
this occurs to a significant extent only within a few days
after exposure, and is not a method normally used to determine
if mercury exposure has occurred.
What recommendations has the federal
government made to protect human health?
The federal government develops regulations
and recommendations to protect public health. Regulations
can be enforced by law. Federal agencies that develop
regulations for toxic substances include the Environmental
Protection Agency (EPA), the Occupational Safety and Health
Administration (OSHA), and the Food and Drug Administration
(FDA). Recommendations, on the other hand, provide
valuable guidelines to protect public health, but cannot
be enforced by law. Federal organizations that develop
recommendations for toxic substances include the Agency for
Toxic Substances and Disease Registry (ATSDR) and the National
Institute for Occupational Safety and Health (NIOSH).
Regulations and recommendations can be
expressed in not-to-exceed levels in air, water, soil, or
food that are usually based on levels that affect animals;
then they are adjusted to help protect people. Sometimes
these not-to-exceed levels differ among federal organizations
because of different exposure times (an 8-hour workday or
a 24-hour day), the use of different animal studies, or other
Recommendations and regulations are also
periodically updated as more information becomes available.
For the most current information, check with the federal agency
or organization that provides it for the substance in which
you are interested. Some regulations and recommendations
for mercury include the following:
EPA and FDA have set a limit of 2 parts
inorganic mercury per billion (ppb) parts of water in drinking
water. EPA is in the process of revising the Water Quality
Criteria for mercury. EPA currently recommends that
the level of inorganic mercury in rivers, lakes, and streams
be no more than 144 parts mercury per trillion (ppt) parts
of water to protect human health (1 ppt is a thousand times
less than 1 part per billion, or ppb). EPA has determined
that a daily exposure (for an adult of average weight) to
inorganic mercury in drinking water at a level up to 2 ppb
is not likely to cause any significant adverse health effects.
FDA has set a maximum permissible level of 1 part of methylmercury
in a million parts (ppm) of seafood products sold through
interstate commerce (1 ppm is a thousand times more than 1
ppb). FDA may seize shipments of fish and shellfish
containing more than 1 ppm of methylmercury, and may seize
treated seed grain containing more than 1 ppm of mercury.
OSHA regulates levels of mercury in the workplace. It has set limits of 0.1 milligrams of mercury per cubic meter of air (mg/m3) for organic mercury and 0.05 mg/m3 for metallic mercury vapor in workplace air to protect workers during an 8-hour shift and a 40-hour work week. NIOSH recommends that the amount of metallic mercury vapor in workplace air be limited to an average level of 0.05 mg/m3 during a 10-hour work shift.
Agency for Toxic Substances and Disease Registry (ATSDR). 1999. Toxicological profile for Mercury. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.
Where can I get more information?
If you have questions or concerns, please contact your community or state health or environmental quality department or:
For more information, contact:
Agency for Toxic Substances and Disease Registry
Division of Toxicology and Human Health Sciences
4770 Buford Highway
Chamblee, GA 30341-3717
Phone: 1-800-CDC-INFO 888-232-6348 (TTY)
Email: Contact CDC-INFO
ATSDR can also tell you the location of occupational and environmental health clinics. These clinics specialize in recognizing, evaluating, and treating illnesses resulting from exposure to hazardous substances.