"They" are: https://www.cdc.gov/niosh/hhe/reports/pdfs/2012-0115-3186.pdf?id=10.26616/NIOSHHETA201201153186
In that case, blood lead levels were not found to be elevated - but adults tend to wash their hands before eating.
I think over all of the threads regarding GAMI 100 approval it has been a theme to point out that the only likely way to get FAA off the X is to get Congress involved. If Quartz (which is not necessarily a serious journalism outlet)is putting out articles, it seem like the issue may be entering...
Awesome! They do link the study (which I'm not going to read).
https://www.researchgate.net/publication/316072809_The_Effect_of_Leaded_Aviation_Gasoline_on_Blood_Lead_in_Children
Seems to me they just scaled the plot to show change. I think the numbers are meaningless. Maybe zero point crossing at the average level of all data points.
There's actually an interesting graph in one of their other articles:
https://qz.com/2173461/leaded-airplane-fuel-is-poisoning-a-new-generation-of-americans/
(I'm no statistician)