What Are Chemical Spills & Their Effects?

A chemical spill is the accidental release of a chemical into the environment. Chemical spills can have drastic effects on people, wildlife and the environment. These effects will depend on where the chemical is released, how much is spilled and, most importantly, the chemical itself. Factors such as the chemical's toxicity, transport properties and environmental persistence will come into play.

What Makes a Spill Dangerous

• A spill is an unintended release of a chemical from some form of containment, such as a drum, a holding pond or a tanker. The word "spill" implies a liquid, but these releases can also involve solid or gaseous chemicals. A release can allow a dangerous chemical to enter the environment -- either through the air, or via water or land. Several factors affect how dangerous a spill is: the toxicity of the chemical, the physical properties of a chemical (whether it is corrosive like an acid or sticky like oil, for example), how far it spreads and how long it stays in the environment. The degree to which a chemical spreads is determined by what are known as its transport properties, and these will vary depending on where it is spilled. A water-soluble chemical like potassium cyanide, for example, would travel widely if spilled into a river but not as far if spilled on pavement. A gaseous chemical like chlorine will travel widely in the air. The persistence of a chemical is determined by how quickly it breaks down when exposed to natural forces like sunlight and microbes. Some chemicals will last for years in the environment whereas others will rapidly degrade.

Toxicity and Physical Hazard Effects

• A poisonous or toxic chemical spill can have rapid and serious health effects on living things nearby. The gas phosgene, for example, can produce immediate breathing problems if inhaled at concentrations as low as one part per million in air. This may have the further effect of forcing evacuation of a large area to ensure that people or animals are not exposed. In 2008, the entire town of Wilkie, Saskatchewan, was evacuated due to a spill of the chemical anhydrous ammonia. Other types of chemicals can also pose an immediate danger due to being corrosive or otherwise physically damaging. Oil spills at sea often kill or injure many seabirds by coating the birds with sticky tar and preventing them from flying. Chemical spills can also have slower, long-term health effects such as cancer. Leaks from underground gasoline holding tanks may fit into this category since they can release benzene, a known carcinogen.

Environmental Effects

• Chemical spills can have severe effects on the environment. These effects can be both obvious and immediate and more subtle and long-term. A large spill of caustic soda into the Cheakamus River in British Columbia in 2005 killed half a million fish. In addition, the long-term effects of the change in the river's pH and the damage to its ecosystem are so drastic that it is estimated the river will take at least 50 years to recover.

Examples of Spills

• The worst industrial chemical release of all time is considered to be the Bhopal disaster in 1984, when the toxic chemical methyl isocyanide escaped from a Union Carbide plant in Bhopal, India. It is estimated that 10,000 died and thousands more were injured. In 2010, a holding pond containing toxic "tailings" from a mine in Hungary broke open and released almost 200 million gallons of mud contaminated with chemicals such as arsenic and mercury. This toxic mix eventually made its way into the Danube, Europe's second longest river. It is estimated that it will take up to a year to repair the environmental damage to the river. In 2010, the BP Deepwater Horizon offshore drilling oil spill became the worst such spill in U.S. history, releasing more than 200 million gallons of oil.