talc
Meaning of talc: A soft mineral with two unrelated medical stories: one about sealing a chest cavity shut, the other about what else the rock contains.
Definition of talc
Talc is a soft mineral built from magnesium, silicon, oxygen and water, ground to a fine powder for industrial and cosmetic use. In medicine a purified sterile grade is placed inside the chest to inflame the two layers lining the lung so that they stick together, closing the space in which fluid or air had been collecting.
How does talc close a space?
By irritating, not by absorbing. Two thin membranes line the lung and the inside of the chest wall, with a slippery film between them that lets the lung slide as it expands. Talc introduced into that gap provokes a strong inflammatory reaction, and as the inflammation settles the two surfaces scar to each other. Once they are stuck together there is no space left for fluid to gather in. The procedure is called pleurodesis, and the powder is a tool for causing controlled scarring rather than a drug that treats anything.
When is it used?
Most often for a pleural effusion caused by cancer, where fluid returns within days of each drainage and the repeated drainage becomes the dominant burden of the illness. It is also used for a lung that keeps collapsing from repeated air leaks. The trade off is permanence: sealing the space relieves breathlessness but rules out later procedures needing access to it, and the reaction itself brings pain and fever for a few days.
How is it delivered?
| Method | How it is given | Setting |
|---|---|---|
| Slurry | Mixed with fluid and run down a chest drain | At the bedside |
| Poudrage | Blown in as dry powder under direct vision | During keyhole chest surgery |
Even coating of the surfaces matters more than the amount used, which is the argument for the surgical route, while the bedside route spares an operation. Both reach the same end state once the coating is complete.
Is talc itself dangerous?
The medical grade and the cosmetic question are separate matters. Talc and asbestos occur together in the same rock, and contamination of cosmetic powder with asbestos fibers is the basis of long running litigation and of concern about body powder. Talc prepared for medical use is purified, free of asbestos, and graded by particle size, since very fine particles can escape the chest and set off a widespread inflammatory reaction. Talc is a mineral in the geological sense rather than a dietary one, and the two senses of that word are unrelated.
Also known as
Used in a sentence
Talc pleurodesis was performed after the effusion reaccumulated twice.
Good to know
Sterile talc for use in the chest is purified and graded by particle size, which separates it from cosmetic talc, where contamination of the source rock with asbestos has driven extensive litigation.