The Core

Auch! God thing I managed to deliver 3 humans then.

in a lot of countries

Basically all the developed nations. This study is just better than the others. I don't think the Swiss (or the Danes Raz) are particularly unique.

estrogen (spelling?) in the water, estrogen in beer.

I doubt it's just one thing. For example, we see trees in the Sierra Nevada struggling to survive for many reasons (drought), but one of the things that is under current research is that tailpipe emissions have added a lot of nitrogen to the soil. That's good if plants need it, but it's not good when it's too much. The air quality in the mountains of California, especially in Sequoia National Park is attrocious and they see those impacts on the plants. That can't be making us more robust.

Depletion of soils and losing key nutrients in foods is perhaps a factor (selenium?)

Then I suspect there are behavioral factors. I know that testosterone increases with hard physical work, assuming there is recovery time. And it decreases with bad sleep. The modern man does little hard physical work and has terrible sleep patterns.

So hormones and medicines in the water is no doubt an issue (apparently fish are being impacted by all the anti-depressants in the water these days). But like most things, there are probably 50 small causes, not one big one.

Xenoestrogens in plastics and foods are a big culprit too.  Along with fertility rates testosterone is falling.

I am not doubting that there are multiple factors.  I posted the above mostly because most people have no idea about xenoestrogens and how to avoid them.  The world is urbanizing too, which isn't all bad.  Urban people have a smaller per-capita footprint than rural folk and the fertility rate falling isn't really a problem when there are so many of us.

Xenoestrogens in plastics and foods are a big culprit too.  Along with fertility rates testosterone is falling.

I had to Google that one, sounded like alien biology at first ;+}