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Comment by karol | Hacker News Reader

I am surprised there's no mention of male fertility. It's a very viable hypothesis in my opinion.

There's an article in American Journal of Men's Health:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9134445/

> In summary, semen quality in men has declined significantly over the last 80 years, with sperm concentration dropping to approximately one seventh of its original value. This timing coincides with the development of plastics.

Not a bad hypothesis.

To be fair, “the last 80 years” coincides with a lot of stuff. The world has changed a lot since the 1940s. Isolating plastics as a cause and accounting for all other variables is next to impossible.

We have really great studies showing plastics disrupting fertility systems in other mammals though.

This hypothesis is not formed merely from “sperm quality has declined since 1940” and “plastic use has gone up since 1940.”

Also coincides with a rise in obesity, which is a known endocrine distruptor.

And correlated with decreased sperm quality and count. Considering the sheer amount of bad health outcomes that are also associated with obesity in general, it's not surprising that it also affects fertility.

Question then becomes, if you adjust for obesity, how much has male fertility changed since 80 years ago?

We have lab data showing that microplastics also disrupt metabolisms. So this is not quite the escape hatch we might wish it was: we have good reason to suspect that microplastics are also contributing to obesity.

(Of course this doesn't fully remove our extremely sedentary lifestyle and highly unnatural food supply either)

Oh most definitely; I rather meant that it would be interesting to see just how much of a contributing factor global obesity rates have in this area.

Tbf, it also coincides with the development of many other things.

Woah. At that rate, how long until everyone is literally infertile? 15 more years? (Yeah, I know, it might not be a linear decline. It's still shocking.)

Many things have changed in the past 80 years...

There's no mention of reproductive health at all. It's a neurological study with some extra data attached. "Thus, we proposed to investigate the effect that exposure to MPs has on young and old C57BL/6J mice, focusing on neurobehavioral effects, inflammatory response, as well as translocation and accumulation of MPs in tissues, including the brain".

> no mention of male fertility.

Divorce rates and video games are already helping to decline that

Also the rising prevalence of trans. Feeling like the other sex might be related to disruption of one's normal sex hormone profile.

Trans people make up a pretty small proportion of the population and are easily controlled for in medical studies.

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