Properties and Health Effects

Summary
Zinc is a naturally occurring element. Exposure to high levels of zinc occurs mostly from eating food, drinking water, or breathing workplace air that is contaminated. Low levels of zinc are essential for maintaining good health. Exposure to large amounts of zinc can be harmful. It can cause stomach cramps, anemia, and changes in cholesterol levels.

What is zinc?
Zinc is one of the most common elements in the earth's crust. It is found in air, soil, and water, and is present in all foods. Pure zinc is a bluish-white shiny metal. Zinc has many commercial uses as coatings to prevent rust,
in dry cell batteries, and mixed with other metals to make alloys like brass, and bronze. A zinc and copper alloy is
used to make pennies in the United States. Zinc combines with other elements to form zinc compounds. Common zinc compounds found at hazardous waste sites include zinc chloride, zinc oxide, zinc sulfate, and zinc sulfide. Zinc compounds are widely used in industry to make paint, rubber, dyes, wood preservatives, and ointments.

What happens to zinc when it enters the environment?
Some is released into the environment by natural processes, but most comes from human activities like mining, steel production, coal burning, and burning of waste. It attaches to soil, sediments, and dust particles in the air. Rain and snow remove zinc dust particles from the air. Depending on the type of soil, some zinc compounds can move into the groundwater and into lakes, streams, and rivers. Most of the zinc in soil stays bound to soil particles and does not dissolve in water. It builds up in fish and other organisms, but it does not build up in plants.

How might I be exposed to zinc?
Ingesting small amounts present in your food and water. Drinking contaminated water or a beverage that has been stored in metal containers or flows through pipes that have been coated with zinc to resist rust. Eating too many dietary supplements that contain zinc. Working on any of the following jobs: construction, painting, automobile mechanics, 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 kind of glass, ceramics, and dyes.

How can zinc affect my health?
Zinc is an essential element in our diet. Too little zinc can cause problems, but too much zinc is also harmful.
Harmful effects generally begin at levels 10-15 times higher than the amount needed for good health. Large doses taken by mouth even for a short time can cause stomach cramps, nausea, and vomiting. Taken longer, it can cause anemia and decrease the levels of your good cholesterol. We do not know if high levels of zinc affect reproduction in humans. Rats that were fed large amounts of zinc became infertile Inhaling large amounts of zinc (as dusts or fumes) can cause a specific short-term disease called metal fume fever. We do not know the long-term effects of breathing high levels of zinc. Putting low levels of zinc acetate and zinc chloride on the skin of rabbits, guinea pigs, and mice caused skin irritation. Skin irritation will probably occur in people.

How likely is zinc to cause cancer?
The U.S. Department of Health and Human Services (DHHS) and the International Agency for Research on Cancer (IARC) have not classified zinc for carcinogenicity. Based on incomplete information from human and animal studies, the U.S. EPA has determined that zinc is not classifiable as to its human carcinogenicity.

How can zinc affect children?
Zinc is essential for proper growth and development of young children. It is likely that children exposed to very
high levels of zinc will have similar effects as adults. We do not know whether children are more susceptible to the
effects of excessive intake of zinc than the adults. We do not know if excess zinc can cause developmental
effects in humans. Animal studies have found decreased weight in the offspring of animals that ingested very high amounts of zinc.

How can families reduce the risks of exposure to zinc?
Children living near waste sites that contain zinc may be exposed to higher levels of zinc through breathing
contaminated air, drinking contaminated drinking water, touching or eating contaminated soil. Discourage your children from eating soil or putting their hands in their mouths and teach them to wash their hands frequently and before eating. If you use medicines or vitamin supplements containing zinc, make sure you use them appropriately and keep them out of the reach of children.

Is there a medical test to determine whether I’ve been exposed to zinc?
There are tests available to measure zinc in your blood, urine, hair, saliva, and feces. These tests are not usually done in the doctor's office because they require special equipment. High levels of zinc in the feces can mean high
recent zinc exposure. High levels of zinc in the blood can mean high zinc consumption and/or high exposure. Tests to measure zinc in hair may provide information on long-term zinc exposure; however, the relationship between levels in your hair and the amount of zinc you were exposed to is not clear.

Has the federal government made recommendations to protect human health?
The U.S. EPA recommends that drinking water should contain no more than 5 milligrams per liter of water (5 mg/L) because of taste. The U.s. EPA requires that any release of 1,000 pounds (or in some cases 5,000 pounds) into the environment be reported to the agency. To protect workers, the Occupational Safety and Health Administration (OSHA) has set an average 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 workweek. Similarly, the National Institute for Occupational Safety and Health (NIOSH) has set the same standards for up to a 10-hour workday over a 40-hour workweek.

References
Agency for Toxic Substances and Disease Registry (ATSDR). 2005. Toxicological Profile for Zinc (Update). Atlanta, GA: U.S. Department of Public Health and Human Services, Public Health Service.

Updated: August 2005