Exactly the same argument could be (and unfortunately, has been) made about vaccines. For all we know, microplastics could be making us healthier. I don't believe that's true, and I'm avoiding plastic where I can, but the fact that we have it doesn't necessarily mean it's bad.
Not really. With vaccines you can have controlled groups (vaccinated or not) and study the benefits versus risks. This is done before any vaccine is introduced to the public, any vaccine showing not enough benefits versus risks is discarded.
We do not have this luxuary with plastic. Controlled groups are not possible, asking that risks inherent to micro-plastics in human body are proven is therefore impossible.
To compare back to vaccines, it would be like vaccinating very single human, with a vaccine which is not tested and which purpose is unknown. Then asking someone to scientifically prove that this vaccine causes health problems as a condition to stop systematically vaccinating every single human.
