But when you do look at the details it doesn't look like the results point to the measured lead coming directly from gasoline itself.
Just as likely if not more so coming from the neighborhood lead smelter that operated over a period of decades where the phaseout probably overlapped from both mineral and gasoline sources, in step with the regulations.
These are rare samples but I wonder if it would be possible to determine how much lead was on the outside of the hairs which could be expected to settle from the atmosphere, compared to within the biological matrix itself which could have been incorporated metabolically?
And in a ubiquitous TEL-using environment, would that form of lead build up more so on the outside of the hairs or the inside?
With or without a lead smelter in the neighborhood?