Also known as: Cyclopentadiene dimer
Chemical reference number (CAS): 77-73-6

Dicyclopentadiene is a man-made substance produced by heating crude oil products. It's a colorless, waxy, flammable solid or liquid, with a camphor-like odor. As dicyclopentadiene enters the air, it breaks down quickly into simpler, less-toxic chemicals. However, it can stay unchanged for a long time in soil and in water.

Dicyclopentadiene is not a common ingredient of products used in homes. It is used to make bug sprays, paints, and varnishes. Most dicyclopentadiene in the environment results from industrial processes and from improper waste disposal.

Exposure Information

Most people are exposed to dicyclopentadiene at work or when the chemical enters the environment.

Air may be contaminated near industries where it's used or in places where it is improperly disposed. If home water supplies are contaminated, people could inhale the chemical while washing, bathing or cooking.

People may be exposed by drinking contaminated water. People who handle contaminated soil may be exposed when they eat or touch their mouths with dirty hands. Although the chemical may irritate the skin, it does not easily pass through the skin.


No standards exist for the amount of dicyclopentadiene allowed in the air of homes. We use a formula to convert workplace limits to home limits. Based on the formula, we recommend levels of dicyclopentadiene be no higher than 0.1 part per million (ppm) in indoor air. Most people can smell dicyclopentadiene when levels reach 0.003 ppm.

The Wisconsin Department of Natural Resources regulates the amount of dicyclopentadiene that can be released by industries.

Currently, there are no state or federal drinking water standards for dicyclopentadiene. Until a health-based standard is developed, people should avoid using water that contains any detectable level of dicyclopentadiene for drinking or for preparing food.

If you have very high levels of dicyclopentadiene in your water supply, you should avoid washing, bathing, or using the water for other purposes.

Health Effects

Everyone's Reaction is Different

A person's reaction to chemicals depends on several things, including individual health, heredity, previous exposure to chemicals including medicines, and personal habits such as smoking or drinking. It’s also important to consider the length of exposure to the chemical, the amount of chemical exposure, and whether the chemical was inhaled, touched, or eaten.

The following symptoms may occur immediately or shortly after exposure to high levels of dicyclopentadiene in air:

  • Irritation of eyes, nose, and throat
  • Temporary changes in kidney and lung functions
  • Headache and loss of balance
  • Convulsions at very high levels

The following health effects can occur after several years of exposure to dicyclopentadiene:

  • Kidney, lung, and nervous system damage may occur after exposure to lower levels over a long period of time. Individuals who smoke may be more sensitive than nonsmokers to the effects of dicyclopentadiene on the lungs.
  • High level dietary exposure did not increase miscarriages or birth defects in exposed fetuses.

If you develop symptoms after you’ve been exposed to dicyclopentadiene, or if you suspect that you may have been exposed to high levels of this chemical, a doctor can use tests of your lungs, kidneys and nervous system to assess possible damage.

Seek medical advice if you have any symptoms that you think may be related to chemical exposure.

Last Revised: October 2, 2019

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