In nature, the majority of talc deposits also contain asbestos. Even worse, the form of asbestos in those deposits is the most cancerous form of it.
So basically what was happening was that women were using baby powder as a absorbent to keep their lady parts feeling fresh, but were introducing a whole bunch of asbestos in the process. This is on top of the dubious idea of putting talc on your hoo-haa to begin with.