It’s very well established that higher levels of lead in the blood of children result in lower IQs and behavioral issues. That is most definitely not pseudo-science. There’s a ton of data behind this. There’s a reason why leaded auto fuel has been banned in every single country in the world.
The question here is what is the relative risk of lead from piston planes, and what can be done about it. I’m certainly not in favor of shutting airports, but the harms of lead aren’t made up.