• There are many pollutants found in landfills.birds at a landfill site in Extremadura/Spain image by Lars Lachmann from Fotolia.com
  
  For many years, landfills contained mostly biodegradable materials and were a relatively safe way to dispose of garbage. As plastics and other synthetic materials gained in popularity, however, landfills became more dangerous to people, as well as the environment. As a result of these materials' decomposition, today's landfills contain many harmful pollutants that may negatively affect air, water, and soil quality, as well as the health of humans and animals.
  
  

Methane

• Methane is a common byproduct of the decomposition that takes place in landfills. This gas adversely affects the ozone layer and contributes to global warming. Landfills can continue to produce this gas even decades after they have been closed.
  
  

Heavy Metals

• Heavy metals, such as lead, mercury, or cadmium, are a common pollutant found in landfills around the world. These metals can contaminate surrounding soil and groundwater, leading to a number of health issues for the local population. Heavy metal exposure may cause skin, respiratory, cardio-vascular, nervous system, and reproductive problems, among others. According to the book "Ecoholic," approximately 50 to 70 percent of heavy metals in landfills come from batteries that haven't been disposed of properly.
  
  

Leachate

• Leachate is a liquid that collects at the base of landfills and may seep into the surrounding soil. This harmful contaminant is created when rainwater or groundwater mixes with common household waste. Its composition and toxicity can vary a great deal, depending on what substances the landfill contains. Landfills with large amounts of hazardous or toxic materials may have a higher concentration of ammoniacal nitrogen, which is very difficult to remove.
  
  

Dioxins

• Dioxins are a type of toxic chemical that can form through gas combustions involving products made from chlorine. They can drastically affect the body's health, causing cancers, nervous system disorders, miscarriages, and birth defects. Dioxin can form from the manufacture and combustion of chlorinated plastics and organic products, including insecticides, herbicides, bleached paper products, and polyvinyl chloride (PVC) found in plastics.