So environmental impact isn't high on their list already, and this BPA issue is very likely going to be completely ignored by anyone in that field.
Naively (without looking at data for concentrations in various environments), I could buy that people regularly handling / being around leaded aviation fuel are worse off than those breathing the (dilute) exhaust products.
:)
But for planes, normal age more than 20 years, even exist workhorses with 70 years.
They have very old engine technologies, some literally spread gas on ground (use lead in it to lubricate valves, which are outside, like on old star engines). So even when you walking where such plane was, you will gather some lead.
Or perhaps a really small turboprop. I've seen really tiny jets so why not stick a prop on it (because jets are too inefficient at low altitudes). Might help with noise too.
There's so much innovation we could be taking advantage of :'( But we're still using engines designed in the 50s with lead (replacement) and manual choke/mixture that cars have deprecated 30 years ago.