Nothing can be done to prevent it, it’s already in every fresh water source.
How worried?
Super fucking worried, but there are also so many other things to be worried about rn that I just accept the fact that I will likely die from some form of forever chemical cancer.
That depends on how aggressively they modify hormones and how long term a view you have.
Will it end the human race?
Probably not.
Will it lead to birth defects and cancer upticks, yup.