It looks like the experiment itself was comparing sperm levels between direct exposure and indirect exposure. That tells us that high concentration and direct exposure reduce sperm and establishes the pesticide as capable of doing that. But it doesn’t tell us much about the global decline. Nothing in the article actually links the two together, and they haven’t even linked the actual study.

We know that some harmful substances are benign in small quantities. The everyday radiation we’re exposed to by naturally occuring isotopes doesn’t do anything. On the other hand, X Rays are safe, but the technicians actually have a noticeable increase in cancer risk if they don’t leave the room when they actually take the X Ray. So the latent background radiation there is enough to make a difference.

Ultimately, we still don’t know if the latent exposure we get to these pesticides is enough to cause reproductive harm. If there isn’t a scientifically significant difference in sperm levels between vegans and non vegetarians, I’m inclined to think this isn’t the culprit. But it’s worth further research and cutting back on usage anyway of course. It could be that we’re exposed to enough to cause a decrease in sperm, but not enough that dietary differences would be visible.

(This is why foods and consumer products can have incredibly complex molecules and still be safe. The concentration makes it benign – most of the time. This is why food additives are an interesting topic.)