The saving grace is that your exhaust doesn't go directly into the bloodstreams of children, likely most of the lead ends up at other places on earth.

>> The EPA's own studies have shown that to prevent a measurable decrease in IQ for children deemed most vulnerable, the standard needs to be set much lower, to 0.02 µg/m3. The EPA identified avgas as one of the most "significant sources of lead".

Maybe stop?

"The study found that for each 5-microgram [per deciliter] increase in blood lead, a person lost about 1.5 IQ points."

https://jamanetwork.com/journals/jama/fullarticle/2613157