Up until the 1980's SOME chips (where customer requested super heavy) contained a piece of lead shot in the center. (Mostly Christy Jones H&C inlaid chips).
Weighting was also achieved through lead powder, tungsten powder or brass powder. The word 'weighted' on an order card could refer to any of these 3, it does not necessarily mean lead.

Additional to this lead, certain color dyes also contained lead.
I have no idea where the 47% came from, per chip it averaged 47ppm (parts per million) when tested for a CA class action lawsuit 20 years or so ago. Some colors were found as high as 200ppm.

In around 1998 lead as a 'weighting' was stopped and some color dyes were replaced.
By 2006 all color dyes either contained no lead or in the case of 7 it was reduced to below the legal amount (19ppm?).
I'm not 100% sure it is totally absent from every dye right now.
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