Many years ago General Motors did a research on where the rubber from tires went as tires wore down. They could not find a trace of rubber on the side of the road.
One would think that with all the millions of tires rolling down the road there should huge mounds of rubber dust piled up but there was none.
House shoes made in China have a marvelous product they use for the soles. It completely disintegrates after a few months.
I have had several pairs with nice uppers — leather and padding. But the soles just dissolved within a year.
Now, I wear an old pair of flipflops I bought for a $buck about 35 years ago. The rubber is still cushiony.