POLYCYCLIC AROMATIC HYDROCARBONS (PAHs)

Information about PaH’s is being made available to help provide answers to basic questions about polycyclic aromatic hydrocarbons. The following information will explain what polycyclic aromatic hydrocarbons are, where they are found, how they can affect your health, and what you can do to prevent or reduce exposure to them.

Polycyclic aromatic hydrocarbons (PAHs) are made whenever substances are burned. PAHs are also found at former coal-gasification sites. Breathing smoke or coming into contact with contaminated soil exposes people to PAHs. Some PAHs may cause cancer and may affect the eyes, kidneys, and liver.

WHAT ARE POLYCYCLIC AROMATIC HYDROCARBONS?

Polycyclic aromatic hydrocarbons are a group of chemicals that occur naturally in coal, crude oil, and gasoline. PAHs are also present in products made from fossil fuels, such as coal-tar pitch, creosote, and asphalt. When coal is converted to natural gas, PAHs can be released. Therefore, some coal-gasification sites may have elevated levels of PAHs. PAHs also can be released into the air during the burning of fossil fuels, garbage, or other organic substances. The less efficient the burning process, the more PAHs are given off. Forest fires and volcanoes produce PAHs naturally.

PAHs are found throughout the environment in the air, water, and soil, and can persist in the environment for months or years. Although hundreds of PAHs exist, some of the more common are listed below:

Acenaphthene Dibenzo(a,h)anthracene
Anthracene Fluoranthene
Benzo(a)anthracene Fluorene
Benzo(a)pyrene Indo(1,2,3-cd)pyrene
Benzo(b)fluorantheneNaphthalene
Benzo(k)fluoranthenePhenanthrene
Chrysene Pyrene

HOW CAN I BE EXPOSED TO PAHs?

Air can be contaminated by PAHs. Levels of PAHs in urban air may be 10 times greater than those found in rural areas. You may be exposed to PAHs in soil near hazardous waste sites or near areas where coal, wood, gasoline or other products have been burned. Low levels of PAHs have been found in some drinking water supplies in the United States.

In the home, PAHs are present in tobacco smoke, smoke from wood burning stoves and fireplaces, creosote-treated wood products, and some foods. Barbecuing, smoking, or charring food over a fire greatly increases the amount of PAHs in the food. Other foods that may contain low levels of PAHs include roasted coffee, roasted peanuts, refined vegetable oil, grains, vegetables, and fruits. A variety of cosmetics and shampoos are made with coal tar and therefore contain PAHs. The PAH compound naphthalene is present in some mothballs.

HOW CAN PAHs AFFECT MY HEALTH?
The health effects that can be caused by exposure to PAHs depend on –

how much has entered the body,
how long you have been exposed to PAHs, and
how the body responds to PAHs.
These effects may be either short-term or long-term.

Short-term health effects

It is not clear that PAHs cause short-term health effects. Other compounds commonly found with PAHs may be the cause of short-term symptoms such as eye irritation, nausea, vomiting, diarrhea, and confusion.

Long-term health effects

Long-term health effects of exposure to PAHs may include cataracts, kidney and liver damage, and jaundice. Repeated skin contact to the PAH naphthalene can result in redness and inflammation of the skin. Breathing or swallowing large amounts of naphthalene can cause the breakdown of red blood cells.

Long-term exposure to low levels of some PAHs have caused cancer in laboratory animals. Benzo(a)pyrene is the most common PAH to cause cancer in animals. Studies of workers exposed to mixtures of PAHs and other compounds have noted an increased risk of skin, lung, bladder, and gastrointestinal cancers. The information provided by these studies is limited because the workers were exposed to other potential cancer-causing chemicals besides PAHs. Although animal studies have shown adverse reproductive and developmental effects from PAH exposure, these effects have generally not been seen in humans.

HOW CAN I REDUCE MY EXPOSURE TO PAHs?

One of the greatest sources of exposure to PAHs is breathing these compounds in tobacco smoke. Smokers can lower their own exposure and the exposure of their families by stopping smoking. People could also reduce their use of wood burning stoves and fireplaces. Additional steps to lower exposure to PAHs include –

decreasing consumption of smoked and charbroiled foods;
decreasing the use of coal-tar-based cosmetics and shampoos;
substituting cedar shavings or aromatic herbs for mothballs, moth flakes, and deodorant cakes;
avoiding skin contact by wearing protective clothing, such as long-sleeve shirts, long pants, and gloves, if you are handling creosote-treated wood products;
avoiding exposure to dust and fumes by wearing an appropriate respirator when working with products containing PAHs.

ARE THERE ANY REGULATIONS FOR PAHs THAT PROTECT HUMAN HEALTH?

The U.S. Environmental Protection Agency (USEPA) has established maximum contaminant levels (MCLs) for public water supplies to reduce the chances of adverse health effects from drinking contaminated water. MCLs are enforceable limits that public water supplies must meet. These standards are much lower than levels at which health effects have been observed. USEPA has not established MCLs for individual PAHs, but has set an MCL for total PAHs of 0.2 parts per billion. There are currently no standards for regulating levels of these chemicals in private wells. USEPA requires the reporting of any releases of PAHs into the environment that exceed one pound. There are no regulations for the PAH content of foods.

WHAT CAN MEDICAL TESTS TELL ME ABOUT MY EXPOSURE TO PAHs?

There are tests available to measure the presence of PAHs in blood or urine. These tests cannot be used to predict potential health effects, but can only confirm that you have been exposed to PAHs. These tests are not routinely available at a doctor’s office because they require special equipment. Some hospitals can provide this testing. If you suspect you are ill from exposure to PAHs, contact your physician.

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