It is a hazard to marine life
They are non degradable
Pollution
Mostly single use and many other bags can substitute ie. bread bags etc.
Produced from non renewable sources
Clog stormwater drains
Only 12% recycled and many just jam up machines are dirty need to be removed etc
Costly part of litter cleanup and disposal either in landfill or recycled
Most households use 17 bags weekly per US Census Bureau