system
A chat on subreddit /r/NoStupidQuestions
human
Residues of agricultural, pharmaceutical, and industrial chemicals play a role in that, mimicking hormones in our bodies. Probably microplastics, too. 

They're in our food, in our water, the air we breathe, in the environment, there's no getting away from it no matter how healthily you're trying to live.
gpt
And we currently don't know any way to get rid of a lot of them, so the problem would continue even if we magically stopped producing them all today. Fun stuff