"Microwood" is basically just cellulose, aka insoluble fiber, which naturally exists in our food. "Microsteel" is just elemental iron which is a necessary nutrient.
Microplastics are novel hydrocarbons that don't exist in nature. They're similar to cellulose but no organisms exist that eat them. They're believed to be nonreactive and therefore harmless but they might bioaccumulate which could be bad, or they might react with things in our bodies in unknown circumstances. We have limited experience with these molecules so it is hard to say.
Microplastics are novel hydrocarbons that don't exist in nature. They're similar to cellulose but no organisms exist that eat them. They're believed to be nonreactive and therefore harmless but they might bioaccumulate which could be bad, or they might react with things in our bodies in unknown circumstances. We have limited experience with these molecules so it is hard to say.