Preface: Introduction to PAHs

What are Polycyclic Aromatic Hydrocarbons?


Polycyclic Aromatic Hydrocarbons (PAHs) are a group of chemicals that occur naturally in coal, crude oil and gasoline. However they become pervasive mainly as a by-product of incomplete combustion. The less efficient the burning process, the more PAHs is given off. Forest fires and volcanoes can produce PAHs naturally, however in the urban context; the most common sources of PAHs are tobacco smoke, automobile exhaust, grilled or charbroiled meat.

Although hundreds of PAHs exist, two of the more common ones are benzo(a)pyrene and naphthalene.

How can I be exposed to PAHs?


PAHs are found throughout the environment in the air, water and soil, and can remain in the environment for months or years. Levels of PAHs in urban air may be 10 times greater than those found in rural areas. You also may be exposed to PAHs in soil near hazardous waste sites or near areas where coal, wood, gasoline or other products have been burned.

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 may contain PAHs.

The PAH compound naphthalene is present in some mothballs and cleaners.

How can PAHs affect my health?


The health effects that can be caused by exposure to PAHs depend on:

• how much has entered your body,
• how long you have been exposed to PAHs and
• how your body responds to PAHs.

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

Possible long-term health effects caused by exposure to PAHs may include cataracts, kidney and liver damage and jaundice. Repeated skin contact with the PAH naphthalene (found in some mothballs) can result in skin redness and irritation. Breathing or swallowing large amounts of naphthalene can cause the breakdown of red blood cells.

Some people who have breathed or touched mixtures of PAHs and other chemicals for long periods of time have developed cancer. Some PAHs have caused cancer in laboratory animals when they breathed air containing them, ingested them in food or had them applied to their skin.

PAHs are stored in the fat tissue of the breast and can increase the propensity for breast cancer. When PAHs are associated with aryl hydrocarbon receptor (AhR), a protein, a series of cellular changes is initiated leading to altered cell signals that increase DNA mutation. PAHs can also be genotoxic, as they are able to interact with the genes directly causing DNA damages.

*Due to the adverse health effects that PAHs could potentially bring, it is necessary that we are able to determine the level of PAHs.


References
http://www.idph.state.il.us/envhealth/factsheets/polycyclicaromatichydrocarbons.htm

http://www.gchromatography.com/gc/polycyclic-aromatic-hydrocarbons-pahs-analysis-using-gas-chromatography