What is in styrofoam that makes it non-biodegradable?

Question

What is in styrofoam that makes it non-biodegradable?

Answer 1

As a synthetic petroleum product, the environment has not been exposed to it before we created it.  As a result, no organism has evolved to break it down.  Such drastic evolution takes many thousands of years.

Answer 2

It's a carbon polymer (polystyrene).  it's non-degradable because the carbon-carbon bonds are strong and there are no known enzymes to degrade these molecules.  Polystyrene was discovered in 1839.  In 1930, BASF started making it.  DOW chemicals produces STYROFOAM for insulation.