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Also known as: White Tar, Tar Camphor, Mothballs, Moth Flakes, Naphthalin
Chemical reference number (CAS): 91-20-3

Naphthalene is either a white solid or a liquid with a strong odor like mothballs. It’s used to make dyes, explosives, plastics, lubricants, and is found naturally in crude oil. It is also found in coal tar wastes at former manufactured gas plants. Coal tars were byproducts at these plants. In homes, naphthalene may be used as a moth repellent or may be released from dyes or new plastic items.

Naphthalene evaporates quickly. Some of the naphthalene that ends up in lakes, streams, or soil evaporates into the air. Naphthalene that seeps through soil into groundwater can remain unchanged for many years.

People breathe naphthalene most often when they’re working with it on the job. People could also breathe the chemical as they visit a chemical cleanup site, use mothballs around their house, do laundry, or bathe with contaminated water. People can be exposed to low levels when they use contaminated water for drinking or preparing food.

Naphthalene can be absorbed through the skin when people handle the chemical, work or play in contaminated soil, or when using contaminated water for activities such as bathing or laundry.

No standards exist for regulating the amount of naphthalene allowed in the air of homes. However, the Wisconsin Department of Natural Resources (DNR) has set a residential indoor air action level for naphthalene at 0.14 parts per billion by volume (ppbv). The action level is considered to be protective of public health. Breathing naphthalene for a lifetime at 0.14 ppbv is very unlikely to be harmful to people. If naphthalene concentrations in air are above the action level, we recommend taking action to halt exposure.

Most people can smell naphthalene at very low levels (40 ppbv).  If you can smell naphthalene, the level is above the residential indoor air action level. The Wisconsin Department of Natural Resources regulates the amount of naphthalene that can be released into outdoor ambient air by industries.

The State drinking water standard for naphthalene is set at 100 parts per billion (ppb).  If levels of naphthalene are very high (above 1,000 ppb) in your water, you may need to avoid washing, bathing, or using the water for other purposes as well. Contact your local public health department for more information specific to your situation.

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.

Immediately or shortly after exposure to a level of 15,000 ppbv of naphthalene in air, a person’s eyes, nose or throat may feel irritated. Naphthalene can also irritate the skin.

Very high levels of naphthalene can cause headaches and nausea. Naphthalene may also damage the liver, kidneys and the eyes.

People can experience anemia after several years of exposure to naphthalene. Anemia can result when high levels of naphthalene are breathed, absorbed through the skin or eaten. Repeated exposure to naphthalene can cause clouding of the eye’s lens and damage vision.


Naphthalene is quickly eliminated from the body. Although naphthalene can be measured in exhaled breath, urine, blood, and other tissues, no reliable method exists to determine the level of your exposure. Doctors can use tests of the eyes and vision, blood, and liver and kidney function to check whether a person has any health effects from naphthalene exposure.

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

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Last revised June 15, 2022