

So! It’s actually kinda crazy how accurate your professor might be. Because progesterone, the chemical in birth control, does indeed break down into estrogen under the right circumstances. The components of broken down progesterone pass through the body via urine, enter the water system, and - this is the important part - is far too small and difficult to be collected or filtered out of the water.
So people taking birth control have absolutley added an insane amount of estrogen to the water supply. And most tap water now does have low levels of estrogen in it because people have been taking birth control for 60+ years.
In that same time, the average age of puberty has continued to fall.
So, it sounds a bit wild, but that theory is far more feasible than most realize.



I am by no means an expert, but there has been a significant amount of studies done on the estrogen in our water levels increasing:
https://pmc.ncbi.nlm.nih.gov/articles/PMC2854760/
This study in 2009 concluded that kids are exposed to more estrogen in milk and food than water, so it shouldn’t be a problem to worry about. However, at least imo, it never looked at overall levels of estrogen intake increasing from all combined sources as water has certainly added to it at least marginally.
So that’s all to say, I’m not 100% behind this being all true, just that there’s actually quite a bit of valid scientific studies that have proven there’s now more estrogen in our drinking and waste water that seems to be at least corolated to our medical use of it.