"While microplastics are anything under 5 millimeters, nanoplastics are defined as particles below 1 micrometer, or a billionth of a meter -- so small they can pass through the digestive system and lungs, entering the bloodstream directly and from there to organs, including the brain and heart. They can also cross the placenta into the bodies of unborn babies.

There is limited research on their impacts on ecosystems and human health, though some early lab studies have linked them to toxic effects, including reproductive abnormalities and gastric issues"