Plastic is a combination of harmful chemicals that negatively impact our environment and it's inhabitants.  We often use plastic for many single use items and then throw it away.  By doing this, we are putting harmful chemicals in the environment that kills our animals.  Most of the plastic we release into the oceans are consumed by most marine life.  The marine life that consumes the plastic that we throw away are often found on our dinner plate.   The plastic that they ingest gets absorbed by our tissue cells.  This means that we are eating the chemicals that are found in the plastic that we have thrown away.  So, not only is it affecting nature and marine life, it's indirectly affecting us.