asbestos
Meaning of asbestos: The same properties that made this mineral useful, its resistance to heat and its needle-like fibers, are what make it hazardous.
Definition of asbestos
Asbestos is a group of naturally occurring silicate minerals that split into long, thin, durable fibers. The fibers resist heat, fire and chemical attack, which made the material a standard choice for insulation, fireproofing and reinforcement in buildings, ships and industrial products. Inhaled fibers lodge in the lungs and are linked to serious disease, so its use is now heavily restricted.
What are the different kinds of asbestos?
Six minerals were mined commercially, and they fall into two families whose fiber shape behaves very differently in the lung.
| Family | Members | Fiber shape and behavior |
|---|---|---|
| Serpentine | Chrysotile, or white asbestos | Curly and layered; accounted for most commercial use and is cleared from the lung faster |
| Amphibole | Crocidolite, amosite, tremolite, actinolite, anthophyllite | Straight and needle-like; persists in lung tissue far longer and is the more potent cause of mesothelioma |
Tremolite is often present as a contaminant of other minerals rather than as a product in its own right, which is how it has turned up in talc and vermiculite.
What happens when the fibers are breathed in?
Intact, undisturbed material is not the problem. Cutting, drilling, sanding or demolishing it releases fibers small enough to stay airborne for hours and to travel past the airway defenses into the smallest air sacs. Immune cells attempt to engulf them and fail, because the fibers are mineral and far too durable to break down. The cells die and release their contents, which recruits more inflammation, and the cycle repeats around a fiber that never disappears. Decades of that low-grade injury produce scarring, chromosome damage in nearby cells, or both.
Which diseases are linked to exposure?
| Condition | What it is |
|---|---|
| Pleural plaques and thickening | Scarred patches on the lining of the lung; common and often symptomless |
| Asbestosis | Widespread scarring of lung tissue itself |
| Mesothelioma | Cancer of the lining of the chest or abdomen, strongly specific to asbestos |
| Lung cancer | Risk raised by asbestos and multiplied further by smoking |
| Laryngeal and ovarian cancer | Also accepted as caused by asbestos exposure |
The scarring disease is asbestosis, the lining cancer is mesothelioma, and lung cancer from asbestos looks no different from lung cancer with any other cause. Evidence for cancers of the stomach, colon and pharynx is weaker and has not been settled, so those sites are described as suspected rather than established.
Why does it still matter?
Disease appears decades after the fibers were breathed in, so cases continue long after an exposure ends. Manufacture and new use are banned or tightly restricted in many countries, but chrysotile is still mined and used in others, and older buildings retain insulation, roofing, floor tiles, pipe lagging and fireproofing that were installed when the material was ordinary. Renovation and demolition are the modern routes of exposure, which is why surveys and controlled removal exist as regulated trades.
Used in a sentence
The building inspection identified deteriorating insulation material suspected of containing asbestos.
Good to know
Disease related to asbestos exposure often does not appear until decades after the original exposure, which distinguishes it from illnesses with a more immediate onset.
Word origin
Where “asbestos” comes from
From Greek asbestos, meaning inextinguishable, formed from a-, not, and sbestos, quenched or extinguished.