This vintage “Horizon Blue” casserole by Pyrex tested positive for the following elements at the following levels (on the painted exterior design with a one-minute test, using an XRF instrument):
Lead (Pb): 72,000 +/- 2,200 ppm
Cadmium (Cd): 33 +/- 11 ppm
Arsenic (As): ND
Mercury (Hg): ND
Gold: (Au) 504 +/- 170 ppm
Platinum (Pt): 1,315 +/- 212 ppm
The amount of lead that is considered toxic to children in a newly manufactured item intended specifically for use by children is anything 90 ppm and higher (in the coating.)
Vintage dishware is not regulated at all for “total lead content as detectable with an XRF” and neither is modern dishware (yet.) [Isn’t it interesting that it was positive for gold and platinum!] NOTE: These vintage Pyrex pieces will also test positive with a reactive agent test (like a LeadCheck swab: http://amzn.to/2DfE3ER affiliate link).
Take away: if you can avoid having vintage Pyrex in your home, I would highly recommend that.