Talcum is a mineral which is often found alongside deposits of asbestos. When the talcum, or talc, is mined asbestos can be collected inadvertently at the same time. Any asbestos is supposed to be removed when the talc is refined into a powder.
Where is talc used in cosmetics?
Talc is commonly used as a dusting powder. But it is also found in a wide range of cosmetics such as eyeliner, face powder, lipstick, blusher and mascara.
Why is this dangerous?
If the talc contains microscopic asbestos fibres these are hazardous. They should not be inhaled. There is a risk from dusting yourself with talcum powder dust, but also when cosmetics begin to dry out and give off dust.
How likely is make-up to be contaminated
Sometimes cornflour is used as a substitute for talc, because it is safer. But where natural talc is still being used how likely is it to be contaminated? In 2020 the United States Food and Drug Administration (the FDA) tested 142 samples from 52 different types of cosmetics. The FDA detected asbestos in 21 of them. Most samples contained less than 1% asbestos, but in one the concentration was 15%. 
In another study, an American non-profit organisation, the Environmental Working Group, found asbestos in a children’s toy make-up kit purchased on-line. In 2019 it said that it had found asbestos in 2,119 products. This was about 1 in 12 of all the samples it had tested over a three year period.