About vegans

[The Grand Nudger]

Industrial chemistry or animals.  No free lunch.

But aren't chemical fertilizers (and pesticides) much more ecologically acceptable and safer than natural ones?

No, and no.

It's well-known that organic farming uses more dangerous pesticides.

Organic and conventional farms use pretty much the same pesticides - which is always fun to explain to someone no matter what kind of farm you're operating.  It's probably important to note that regenerative and organic are not interchangeable, as well.  Regenerative agriculture is geared towards reducing the environmental cost of production - and in some cases they would not qualify or even attempt to qualify as organic.  

Besides, natural fertilizers are usually dead plants, because it's forbidden to use dead animals or animal excrement as fertilizers, because they might contain dangerous bacteria that can attack both humans and those animals, and which can survive being outside of host for some time. For similar reasons, though not quite as strong, it's safer to use synthetic fertilizers rather than dead plants.

I'm assuming that you're referring to compost when you mention dead plants, which isn't entirely accurate but close enough. Those plants still had to grow..and be fertilized, somehow. It's not generally forbidden to use manure (laws may be different where you are), there's a time to harvest restriction on raw manure.  Synthetic fertilizers also have time to harvest restrictions on account of toxicity.

(As do pesticides, or..really..any application of anything whatsoever to any crop intended for human consumption - they even have return intervals - an amount of time before you can walk in the rows after application, safely. Exposure risks and concerns are orders of magnitude greater for ag workers than for the end consumer.)