[SML] advice on some old pigment

[Paul Schreiner]

So I'm cleaning the paint area at my new(ish) gig from a couple dozen
years or so worth of accumulated detritus and random stuff, and I came
across what used to be a 20 lb. bag of dry "chrome yellow medium"
pigment from Gothic Color in New York.  There's still a couple of
pounds left, but the brown paper bag it was purchased in had
deteriorated and is leaking.

While I generally am getting dangerously close to Auld Pharte
territory, this is something I've never actually worked with.  It's
obvious that I either need to dispose of it or find better storage,
but since I don't know how it would have been used, I'm not sure which
way to go.  Is this something that mixes with latex?  If I dispose of
it, what environmental precautions do I have to take?  Teh Google is
demonstrably uninformative on this, because all the links I've found
for Gothic Color pigments relating to theatre are pages from textbooks
dating from 1945-1983 (with one cryptic reference found in W. Joseph
Stell's "Scenery: Design and Fabrication" from 2001).  Any
suggestions?  TIA