Disclaimer: I am quite firmly in that camp now, although at first I considered them all nutters. Some thing has been driving global ill-health in our post-disease world (excluding viruses) from 1920 onwards... imho there's clearly a complex ætiology with factors such as:

- carbohydrate (especially fructose) vs animal-protein/-fat consumption

- types of fat (our bodies only contain certain kinds)

- xenœstrogen & hormones of all types not just phyto-œstrogens

- Vitamin D, Magnesium, ferritin, pre-eclampsia, anæmia (lack of hæme iron consumption)

- more recently the whole statin-cholesterol debacle, Goodhart's law in action

so soy protein, dried or boiled soybeans, tofu, tempeh, and meatless soy products....but Koreans have been eating it forever. perhaps the processing in mass industrial scale has impact?

yeah I heard of the plastic theory and I think the air pollution in Korea is an overlooked factor. The fine dust particulates must have some impact on the reproduction system.

maybe even Ramen? Koreans consume a ton of instant ramen. High rate of alcohol?

I am interested to hear more about the impact of plastic. It is unavoidable and its widely used in Asia.

...what I really think is contraceptives is having an impact and that we are politically blocked from discussing it. What happened in Korea since 2010s? Huge amount of contraceptive pills were sold as society adopted a more laissez faire attitude towards sex. 10 years later those women are not trying to have babies and cannot. Is this too far fetched?

We are seeing the same issue in most western countries that correlate with high contraceptive usage. There is just less children being born but not an issue where contraception is tough.

If it’s contraceptives it might be possible to create a comparison group with some stricter religious group that does not take contraceptives and measure fertility levels between that group and a group that did take contraceptives.

> Some Artificial hormones are found in plastic, rates go up when it's recycled plastics.

I do know that some chemicals, possibly also found in some plastics (soft plastic probably) function a bit like estrogen, potentially reducing male fertility.