Everywhere scientists have looked for them they have found tiny bits of degraded plastic—including, now, in human poop.

from https://www.scientificamerican.com/article/microplastics-have-been-found-in-people-rsquo-s-poop-what-does-it-mean/
https://static.scientificamerican.com/sciam/cache/file/8DA88562-2458-410B-951538DFCF0C1EEB_source.jpg?w=590&h=800&FB81B491-470B-45CC-9EEF9BE365B8A4DF