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CDC - Cancer Cluster archived website note

Historical Document

This document is provided by the National Center for Environmental Health ONLY as an historical reference for the public health community. It is no longer being maintained and the data it contains may no longer be current and/or accurate.

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What is benzene?

Benzene is a chemical formed from both natural processes and human activities. Natural sources of benzene include volcanoes and forest fires. Benzene is also a natural part of crude oil, gasoline, and cigarette smoke.

Industrial processes are the main source of benzene in the environment. Benzene is widely used in the United States; it ranks in the top 20 chemicals used.

Some industries use benzene to make other chemicals that are in plastics, resins, and nylon and synthetic fibers. Benzene is also used to make some types of rubbers, lubricants, dyes, detergents, and pesticides. Benzene is one of the major components of JP-8 fuel.

What happens to benzene when it enters the environment?

  • Benzene can pass into the air from water and soil.
  • It reacts with other chemicals in the air and breaks down within a few days.
  • Benzene in the air can attach to rain or snow and be carried back to the ground.
  • Benzene breaks down more slowly in water and soil and can pass through the soil into underground water.
  • Benzene does not build up in plants or animals.

How can people be exposed to benzene?

Most people are exposed to a small amount of benzene every day.

People can be exposed by breathing air contaminated with benzene.

  • Outdoor air contains low levels of benzene from tobacco smoke, automobile service stations, exhaust from motor vehicles, and industrial emissions.
  • Indoor air usually contains higher levels of benzene because of products that contain it, such as glue, paint, furniture wax, and detergent.
  • Air around hazardous waste sites or gas stations contains higher levels of benzene.
  • People working in industries that make or use benzene can be exposed to the highest levels of it.

People can be exposed by eating food or drinking water contaminated with benzene. Leaks from underground storage tanks or from hazardous waste sites containing benzene can contaminate well water.

A major source of benzene exposure is tobacco smoke.

People can absorb benzene through their skin from the air or by touching soil or water that contain benzene.

Can exposure to benzene make people sick?

Yes. The severity of illness of benzene exposure usually depends on both the amount of exposure and how long the exposure lasted.

Exposure to levels of benzene can cause severe skin and eye irritation, drowsiness, dizziness, extreme happiness, rapid heartbeat, headaches, nausea, vomiting, and confusion. Exposure to high levels of benzene can cause these problems plus blurred vision, tremors, seizures, irregular heartbeat, unconsciousness, and even death.

Exposure to benzene over a long time can cause headache, loss of appetite, drowsiness, and nervousness but mostly affects the blood. Benzene harms the bone marrow and can lower the number of red blood cells, which can cause anemia. It can also cause abnormal bleeding and can harm the immune system, which increases the chance for infection.

Can benzene cause any types of cancer?

Yes. Benzene can cause cancer in humans who work with it. It can cause acute nonlymphocytic leukemia (acute myelocytic leukemia or AML) and might cause chronic nonlymphocytic leukemia and chronic lymphocytic leukemia. Benzene exposure also has been linked with other kinds of blood cancers and disorders such as preleukemia blood marrow disorders and aplastic anemia, Hodgkins lymphoma, and myelodysplastic syndrome.

Can benzene cause leukemia?

Yes. Benzene-exposed workers in the chemical, shoemaking, and oil refineries industries have higher risks of getting leukemia, especially AML.

Can benzene cause reproductive problems?

Benzene may harm the reproductive organs. Some women workers who breathed high levels of benzene for many months had irregular menstrual periods and their ovaries became smaller, but studies in these women did not prove that benzene caused these problems.

Can benzene cause developmental problems?

We do not know whether benzene exposure affects the developing fetus. However, offspring of pregnant animals who breathed benzene had low birth weights, slow bone formation, and bone marrow damage. We do not know whether benzene affects fertility in men.

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