why are polythene bags are dangerous?

• Polythene bags are dangerous because they are non-biodegradable.
• It takes thousands of years for its natural biodegradation.
• It makes the soil less fertile when thrown on land.
• When thrown in water it chokes  ponds, rivers and oceans. It harms the sea life.
• If animals eat plastic, it gets stuck in their stomach. It makes them sick, because the bacteria in their stomach cannot break the plastic into smaller pieces.