Yellow and White Swirled Glass Vintage Marble: 2,364 ppm Lead!
The amount of lead that is considered toxic in the substrate of a newly manufactured item intended for use by children is anything 100 ppm lead or higher. Tested in 2014 with an XRF instrument. Year of manufacture and brand: unknown.
Once I learned that even new marbles could have high levels of lead (including the squashed marbles often called “dragon tears” and used as counters in the Waldorf School environment), I decided to stop letting my children play with them on a regular basis, until they got fully past the stage of putting things in their mouths.
I have probably tested hundreds of marbles over the years and I have found that the new ones with the iridescent coatings are often high lead and so I specifically try to avoid those, as the chance of exposure to a child is potentially greater if the lead is in the coating (vs. the substrate/ the main component of the glass of the marbles.)
As always, if you have any questions please let me know!