Public Health Statement for Zinc
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This Public Health Statement is the summary chapter from the Toxicological Profile for Zinc. 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 zinc and the effects of exposure to it. Zinc is an essential element needed by your body and is commonly found in nutritional supplements. However, taking too much zinc into the body can affect your health.
The Environmental Protection Agency (EPA) identifies the most serious hazardous waste sites in the nation. These sites are then placed on the National Priorities List (NPL) and are targeted for long-term federal clean-up activities. Zinc has been found in at least 985 of the 1,662 current or former NPL sites. Although the total number of NPL sites evaluated for zinc is not known, the possibility exists that the number of sites at which zinc is found may increase in the future as more sites are evaluated. This information is important because these sites may be sources of exposure and exposure to zinc may harm you.
When a substance is released either from a large area, such as an industrial plant, or from a container, such as a drum or bottle, it enters the environment. Such a release does not always lead to exposure. You can be 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 zinc, many factors will determine whether you will 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 any other chemicals you are exposed to and your age, sex, diet, family traits, lifestyle, and state of health.
What is zinc?
Zinc is one of the most common elements
in the Earth's crust. Zinc is found in the air, soil, and
water and is present in all foods. In its pure elemental (or
metallic) form, zinc is a bluish-white, shiny metal. Powdered
zinc is explosive and may burst into flames if stored in damp
places. Metallic zinc has many uses in industry. A common
use for zinc is to coat steel and iron as well as other metals
to prevent rust and corrosion; this process is called galvanization.
Metallic zinc is also mixed with other metals to form alloys
such as brass and bronze. A zinc and copper alloy is used
to make pennies in the United States. Metallic zinc is also
used to make dry cell batteries.
Zinc can also combine with other elements,
such as chlorine, oxygen, and sulfur, to form zinc compounds.
Zinc compounds that may be found at hazardous waste sites
are zinc chloride, zinc oxide, zinc sulfate, and zinc sulfide.
Most zinc ore found naturally in the environment is in the
form of zinc sulfide. Zinc compounds are widely used in industry.
Zinc sulfide and zinc oxide are used to make white paints,
ceramics, and other products. Zinc oxide is also used in producing
rubber. Zinc compounds, such as zinc acetate, zinc chloride,
and zinc sulfate, are used in preserving wood and in manufacturing
and dyeing fabrics. Zinc chloride is also the major ingredient
in smoke from smoke bombs. Zinc compounds are used by the
drug industry as ingredients in some common products, such
as vitamin supplements, sun blocks, diaper rash ointments,
deodorants, athlete's foot preparations, acne and poison ivy
preparations, and antidandruff shampoos.
What happens to zinc when it enters the environment?
Zinc enters the air, water, and soil
as a result of both natural processes and human activities.
Most zinc enters the environment as the result of mining,
purifying of zinc, lead, and cadmium ores, steel production,
coal burning, and burning of wastes. These activities can
increase zinc levels in the atmosphere. Waste streams from
zinc and other metal manufacturing and zinc chemical industries,
domestic waste water, and run-off from soil containing zinc
can discharge zinc into waterways. The level of zinc in soil
increases mainly from disposal of zinc wastes from metal manufacturing
industries and coal ash from electric utilities. Sludge and
fertilizer also contribute to increased levels of zinc in
the soil. In air, zinc is present mostly as fine dust particles.
This dust eventually settles over land and water. Rain and
snow aid in removing zinc from air. Most of the zinc in lakes
or rivers settles on the bottom. However, a small amount may
remain either dissolved in water or as fine suspended particles.
The level of dissolved zinc in water may increase as the acidity
of water increases. Fish can collect zinc in their bodies
from the water they swim in and from the food they eat. Most
of the zinc in soil is bound to the soil and does not dissolve
in water. However, depending on the type of soil, some zinc
may reach groundwater, and contamination of groundwater has
occurred from hazardous waste sites. Zinc may be taken up
by animals eating soil or drinking water containing zinc.
Zinc is also a trace mineral nutrient and as such, small amounts
of zinc are needed in all animals.
How might I be exposed to zinc?
Zinc is an essential element needed by
your body in small amounts. We are exposed to zinc compounds
in food. The average daily zinc intake through the diet in
this country ranges from 5.2 to 16.2 milligrams (milligram=0.001
gram). Food may contain levels of zinc ranging from approximately
2 parts of zinc per million (2 ppm) parts of foods (e.g.,
leafy vegetables) to 29 ppm (meats, fish, poultry). Zinc is
also present in most drinking water. Drinking water or other
beverages may contain high levels of zinc if they are stored
in metal containers or flow through pipes that have been coated
with zinc to resist rust. If you take more than the recommended
daily amount of supplements containing zinc, you may have
higher levels of zinc exposure.
In general, levels of zinc in air are
relatively low and fairly constant. Average levels of zinc
in the air throughout the United States are less than 1 microgram
of zinc per cubic meter (μg/m3) of air, but range from
0.1 to 1.7 μg/m3 in areas near cities.
Air near industrial areas may have higher
levels of zinc. The average zinc concentration for a 1-year
period was 5 μg/m3 in one area near an industrial source.
In addition to background exposure that
all of us experience, about 150,000 people also have a source
of occupational exposure to zinc that might elevate their
total exposure significantly above the average background
exposure. Jobs where people are exposed to zinc include zinc
mining, smelting, and welding; manufacture of brass, bronze,
or other zinc-containing alloys; manufacture of galvanized
metals; and manufacture of machine parts, rubber, paint, linoleum,
oilcloths, batteries, some kinds of glass and ceramics, and
dyes. People at construction jobs, automobile mechanics, and
painters are also exposed to zinc.
How can zinc enter and leave my body?
Zinc can enter the body through the digestive
tract when you eat food or drink water containing it. Zinc
can also enter through your lungs if you inhale zinc dust
or fumes from zinc-smelting or zinc-welding operations on
your job. The amount of zinc that passes directly through
the skin is relatively small. The most likely route of exposure
near NPL waste sites is through drinking water containing
a high amount of zinc. Zinc is stored throughout the body.
Zinc increases in blood and bone most rapidly after exposure.
Zinc may stay in the bone for many days after exposure. Normally,
zinc leaves the body in urine and feces.
How can zinc affect my health?
Scientists use many tests to protect
the public from harmful effects of toxic chemicals and to
find ways for treating persons who have been harmed.
One way to learn whether a chemical will
harm people is to determine how the body absorbs, uses, and
releases the chemical. For some chemicals, animal testing
may be necessary. Animal testing may also help identify health
effects such as cancer or birth defects. Without laboratory
animals, scientists would lose a basic method for getting
information needed to make wise decisions that protect public
health. Scientists have the responsibility to treat research
animals with care and compassion. Scientists must comply with
strict animal care guidelines because laws today protect the
welfare of research animals.
Inhaling large amounts of zinc (as zinc
dust or fumes from smelting or welding) can cause a specific
short-term disease called metal fume fever, which is generally
reversible once exposure to zinc ceases. However, very little
is known about the long-term effects of breathing zinc dust
Taking too much zinc into the body through
food, water, or dietary supplements can also affect health.
The levels of zinc that produce adverse health effects are
much higher than the Recommended Dietary Allowances (RDAs)
for zinc of 11 mg/day for men and 8 mg/day for women. If large
doses of zinc (10-15 times higher than the RDA) are taken
by mouth even for a short time, stomach cramps, nausea, and
vomiting may occur. Ingesting high levels of zinc for several
months may cause anemia, damage the pancreas, and decrease
levels of high-density lipoprotein (HDL) cholesterol.
Eating food containing very large amounts
of zinc (1,000 times higher than the RDA) for several months
caused many health effects in rats, mice, and ferrets, including
anemia and injury to the pancreas and kidney. Rats that ate
very large amounts of zinc became infertile. Rats that ate
very large amounts of zinc after becoming pregnant had smaller
babies. Putting low levels of certain zinc compounds, such
as zinc acetate and zinc chloride, on the skin of rabbits,
guinea pigs, and mice caused skin irritation. Skin irritation
from exposure to these chemicals would probably occur in humans.
EPA has determined that because of lack of information, zinc
is not classifiable as to its human carcinogenicity.
Consuming too little zinc is at least
as important a health problem as consuming too much zinc.
Without enough zinc in the diet, people may experience loss
of appetite, decreased sense of taste and smell, decreased
immune function, slow wound healing, and skin sores. Too little
zinc in the diet may also cause poorly developed sex organs
and retarded growth in young men. If a pregnant woman does
not get enough zinc, her babies may have birth defects.
How can zinc affect children?
This section discusses potential health
effects in humans from exposures during the period from conception
to maturity at 18 years of age.
Zinc is essential for proper growth and
development of young children. Mothers who did not eat enough
zinc during pregnancy had a higher frequency of birth defects
and gave birth to smaller children (lower birth weight) than
mothers whose zinc levels were sufficient. Very young children
who did not receive enough zinc in the diet were smaller,
both in length and in body weight, than children who ate enough
zinc. Some foods, such as soy-based formulas, contain high
levels of phytate, which can result in a decreased absorption
of zinc in the diet. Too much of these foods may result in
effects similar to those that occur when children receive
too little zinc in the diet.
Little is known about whether children
who eat too much zinc will react differently from adults who
have ingested large amounts of zinc. A child who accidentally
drank a large amount of a caustic zinc solution was found
to have damage to his mouth and stomach, and later to his
pancreas, but similar effects have been seen in adults who
accidentally drank the same solution.
How can families reduce the risk of exposure to zinc?
If your doctor finds that you have been
exposed to substantial amounts of zinc, ask whether your children
might also have been exposed. Your doctor might need to ask
your state health department to investigate.
Children living near waste sites containing
zinc are likely to be exposed to higher environmental levels
of zinc through breathing, drinking contaminated drinking
water, touching soil, and eating contaminated soil. It is
unlikely that a child would ingest enough zinc from eating
soil to cause harmful effects. However, parents should supervise
to see that children avoid eating soil and wash their hands
frequently, especially before eating. Parents should consult
their family physicians about whether (and how) hand-to-mouth
behaviors in their children might be discouraged.
Children and adults require a certain
amount of zinc in the diet in order to remain healthy. However,
overuse of some medicines or vitamin supplements containing
zinc might be harmful; these medicines should always be used
appropriately. If you are accidentally exposed to large amounts
of zinc, consult a physician immediately.
Is there a medical test to determine whether I have been exposed to zinc?
Medical tests can determine
whether your body fluids contain high levels of zinc. Samples
of blood or feces can be collected in a doctor's office and
sent to a laboratory that can measure zinc levels. It is easier
for most laboratories to measure zinc in blood than in feces.
The presence of high levels of zinc in the feces can mean recent
high zinc exposure. High levels of zinc in the blood can mean
high zinc consumption and/or high exposure. High zinc levels
in blood or feces reflect the level of exposure to zinc. Measuring
zinc levels in urine and saliva also may provide information
about zinc exposure. Tests to measure zinc in hair may provide
information on long-term zinc exposure; however, no useful correlation
has been found between hair zinc levels and zinc exposure and
these tests are not routinely used. Since zinc levels can be
affected by dietary deficiency and cell stress, these results
may not be directly related to current zinc exposure.
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. The EPA, the Occupational Safety and
Health Administration (OSHA), and the Food and Drug Administration
(FDA) are some federal agencies that develop regulations for
toxic substances. Recommendations provide valuable guidelines
to protect public health, but cannot be enforced by law. The
Agency for Toxic Substances and Disease Registry (ATSDR) and
the National Institute for Occupational Safety and Health
(NIOSH) are two federal organizations that develop recommendations
for toxic substances.
Regulations and recommendations can be
expressed as "not-to-exceed" levels, that is, levels
of a toxic substance in air, water, soil, or food that do
not exceed a critical value that is usually based on levels
that affect animals; they are then adjusted to levels that
will help protect humans. Sometimes these not-to-exceed levels
differ among federal organizations because they used different
exposure times (an 8-hour workday or a 24-hour day), different
animal studies, or other factors.
Recommendations and regulations are also
updated periodically as more information becomes available.
For the most current information, check with the federal agency
or organization that provides it. Some regulations and recommendations
for zinc include the following:
The federal government has set standards
and guidelines to protect individuals from the potential health
effects of excessive zinc. EPA has stated that drinking water
should contain no more than 5 mg of zinc per liter of water
(5 mg/L or 5 ppm) because of taste. Furthermore, any release
of more than 1,000 pounds (or in some cases 5,000 pounds)
of zinc or its compounds into the environment (i.e., water,
soil, or air) must be reported to EPA.
The National Academy of Sciences (NAS)
estimates an RDA for zinc of 11 mg/day (men). Eleven mg/day
is the same as 0.16 mg per kilogram (kg) of body weight per
day for an average adult male (70 kg). An RDA of 8 mg/day,
or 0.13 mg per kg of body weight for an average adult female
(60 kg), was established for women because they usually weigh
less than men. Lower zinc intake was recommended for infants
(2-3 mg/day) and children (5-9 mg/day) because of their lower
average body weights. The RDA provides a level of adequate
nutritional status for most of the population. Extra dietary
levels of zinc are recommended for women during pregnancy
and lactation. An RDA of 11-12 mg/day was set for pregnant
women. Women who nurse their babies need 12-13 mg/day.
To protect workers, OSHA has set an average legal limit of 1 mg/m3 for zinc chloride fumes and 5 mg/m3 for zinc oxide (dusts and fumes) in workplace air during an 8 hour workday, 40 hour work week. This regulation means that the workroom air should contain no more than an average of 1 mg/m3 of zinc chloride over an 8 hour working shift of a 40 hour work week. NIOSH similarly recommends that the level of zinc oxide in workplace air should not exceed an average of 1 mg/m3 over a 10 hour period of a 40 hour work week.
Agency for Toxic Substances and Disease Registry (ATSDR). 2005. Toxicological profile for Zinc. 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.