What it is:

• Chemical symbol: C6H6. An organic chemical, benzene is one of the aromatic hydrocarbons.
• Colorless or light yellow liquid at room temperature. Sweet odor, highly flammable.
• Benzene dissolves easily in water: 0.8 grams per liter (800 milligrams per liter [mg/L], or 800 parts per million [ppm]), at 77 degrees F (25 C). Will float on top of water.
• Evaporates quickly at room temperature. As a vapor, it is heavier than air. Boils at 176 degrees F (80.1 C).

Occurrence:

• Occurs in nature from incomplete combustion of carbon-rich materials, such as in volcanoes and forest fires.
• Natural constituent of crude oil
• Produced from coal or petroleum (usually the latter). Ranks among the top 20 chemicals in production volume. Used to make solvents, detergents, plastics, resins, paint and many other products.
• An ingredient of gasoline, benzene is found in groundwater contaminated by leaking underground fuel storage tanks, or in surface water subject to fuel spills. Gasoline contains a bit less than 1% benzene.
• Occurs in very low levels in outdoor air. Slightly higher levels indoors due to paints, glues, etc. Higher also in air near exhaust emissions, service stations, places where solvents used.
• Tobacco smoke contains benzene.
• Released with the burning of polyvinyl chloride (PVC).

Health Effects:

• A carcinogen in humans. Long-term exposure to heavy levels in air causes leukemia. Most at risk: people who work in industries that make or use benzene.
• Drinking water or eating food containing high levels can cause vomiting, dizziness or death within minutes to hours.
• Breathing in high levels over a short period can cause drowsiness, dizziness, unconsciousness and death.

Regulation:

• US Environmental Protection Agency (EPA) Primary Drinking Water Standards maximum contaminant level (MCL) in water: 0.005 mg/L (5 parts per billion, or 5 micrograms per liter).
• Accidental spills of benzene into the environment of greater than 10 pounds (4.5 kilograms) must be reported to EPA.
• Precaution: Water suspected of containing benzene should not be consumed, and bottled water should be substituted until the water source is safe to drink.

Water treatment:

• Adsorption with granular activated carbon filter.
• Ozonation.