The Sperm-Count ‘Crisis’ Doesn’t Add Up

"When I started looking at phthalates, around 2000, phthalate syndrome had been shown experimentally in rodents but not in humans. Mother rats given phthalates had male babies with a smaller penis and scrotum, their sperm counts were lower and their AGD was shorter. I ran a study where we measured the stored urine of pregnant women for phthalates and we measured their male babies’ and toddlers’ AGDs – a first – along with some other genital measurements. We found exactly what had been found in rodents: phthalate syndrome. I then did a study of college-age men, where we got them to give a semen sample and measured their AGD, and we showed that the shorter the AGD, the lower the sperm count. This is why I am confident: we have a direct link from phthalates to short AGD and then from short AGD to low sperm count, and those results have been confirmed by subsequent studies."

From https://www.theguardian.com/society/2021/mar/28/shanna-swan-...

This debunking... really isn't. To pick a random example:

> For starters, no one knows what an “optimal” sperm count is. The World Health Organization sets a range of “normal” sperm count as from 15 to 250 million sperm per milliliter. (Men produce about 2 to 5 milliliters of semen per ejaculation.) But it isn’t clear that more is better. Above a certain threshold — 40 million per milliliter, according to the W.H.O. — a higher sperm count does not mean a man is more fertile.

It doesn't follow from this that there is no sperm-count crisis. Since the marginal energy cost of more sperm is pretty small, you'd expect that evolution would build a generous safety margin on the sperm count required to achieve reproduction, and we can be in a "crisis" if we're shrinking that safety margin even if it hasn't reached zero yet. e.g, suppose the threshold is 25MM/mL and a "normal" count is 100MM/mL; a decrease to 40MM/mL can be a crisis even if it hasn't had any visible effects yet. Not to mention that whole paragraph completely disregards the possibility that falling sperm counts are as much a symptom of declining health as a cause of problems unto themselves.

summary: This article contains a lot of speculation, but none of it contradicts the evidence that sperm counts have dropped.

I makes the argument that that might not reduce fertility as much as other scientists assume, and so we don't really know if there's an actual crisis happening.

Def from nano plastics.