Back when The Wizard of Oz was fresh and new and novel, Hollywood (and the world that shaped it) had very different ideas of what was “safe” than we do today. Asbestos was used in holiday decorations distributed across America, posing health risks for people who took Christmas and other celebrations seriously. Just as alarming is the fact that chrysotile, which is white asbestos and the most commonly used form of the dangerous substance, was used in roofing, brake pads and shoes, interior fire doors, stage curtains, popcorn ceilings, and many, many other types of building materials people that were around every day.
Article source: https://www.cinemablend.com/news/2478684/that-time-the-wizard-of-oz-used-asbestos-for-its-fake-snow