The majority of microplastics that you eat are shitted out.

What you should be concerned about are airborne microplastics which you inhale into your lungs, because they go straight to your heart and then get distributed around your body through your bloodstream.

About 95% or airborne microplastics come from car tires.

Car tires are constantly shedding microplastics, whenever a car is moving those microplastics become airborne