It's in a plastic bag!

A plastic bag is your life.
It holds securely
but it also suffocates.
The one you hold securely starts to rot,
it sticks to your sides discharging gunk.
The gunk leaks its way out.
Some of the gunk is left inside the plastic bag.
It stays immobile in this plastic bag and
doesn't leave it
The plastic bag glides from a posh kitchen's garbage bin to a ditch in the slums.
But it all stays: the gunk and the plastic bag!
Plastic is not bio-degradable, you see!