https://www.wgbh.org/news/health/2024-11-19/thousands-of-mas...
Microplastic risk is not anywhere close to lead, we should not even be discussing these two things in the same paragraph.
Lead is bad because it mimics calcium and iron in our body, binding to proteins, sneaking into bones, causes anemia, disrupts brain function...
Plastic is inert, it is made of long chains of carbon, hydrogen and oxygen. These long chains do not break down easily. Microplastic, while it does not pass through the body, and can accumulate in organs, its impact is still under study. We aren't ingesting high doses.
BUT, bad pipes may leach other stuff. Some additives in certain plastics seem to mimic hormones and potentially disrupt them. Some additives are carcinogenic. (but only in high doses I guess). Certified modern pipes are safer.