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Asbestos in a Nutshell

This miracle material has taught us some lessons

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idria asbestos

Chrysotile asbestos from the New Idria district, California.

Photo (c) Andrew Alden, licensed to About.com (fair use policy)

In 2000 the Seattle Post-Intelligencer reported on an unusual contaminant in children's crayons—asbestos! An uproar followed the articles, but in truth there was no hazard.

It goes to show how low our opinion of asbestos has sunk. Once asbestos was valued fireproofing and insulation, saving lives and adding comfort to every building and home. These days, thanks in part to asbestos, we're more careful about how we adopt new technology.

Three different sets of specialists talk about asbestos, and they each mean different things.

The Builder's View of Asbestos

The long, flexible fibers of certain minerals have been woven into fireproof cloth and other curiosities since ancient times. Natural asbestos has also been called mountain flax, earth flax, and mountain leather. Roman chronicles tell of restaurants that used asbestos tablecloths, which could be quickly cleaned in fire for ready reuse. It was not a major infrastructural commodity, but it was popular enough to be an item of international trade.

In the late 1800s, asbestos found many new uses. Powdered asbestos was especially useful, a superb material wherever tough, fireproof, chemically inert insulation or reinforcement was needed. Asbestos became a big industry, and uses of the material expanded with the supply. Home siding, appliance insulation, floor tiling, water mains and vehicle brakes all incorporated this high-performance material.

The Geologist's View of Asbestos

Geologists studied the minerals making up asbestos and discovered large deposits in Canada, the United States, Australia, China, Russia and South Africa. Asbestos has no mineralogical meaning—it's a label for any of the fibrous (asbestiform) varieties of several different minerals.

  • What industry calls brown asbestos or amosite is a mixture of asbestiform minerals of the grunerite-cummingtonite series and the gedrite-anthophyllite series. It is no longer produced, but may persist in old structures and products.
  • Blue asbestos or crocidolite is asbestiform riebeckite. It too is no longer mined.
  • White asbestos is the mineral chrysotile. This is the only asbestos mineral that occurs strictly as fibers, and the only one in the serpentine group. The others normally occur in other crystal forms, and they are in the amphibole group.
  • Asbestiform actinolite-tremolite has no commercial name, and it occurs in commerce only as an impurity. It is also an amphibole. The Seattle crayons contained tremolite.

The Medical/Regulatory View of Asbestos

It was noted in ancient times that the miners and artisans who worked with asbestos were prone to lung trouble and shortened lives.

After the modern explosion of the asbestos industry, doctors and regulators got involved when factory workers began dying. They determined that blue and brown asbestos and actinolite-tremolite—the amphibole asbestos minerals—are especially bad news, causing cancers and deadly lung conditions in miners, factory workers and their families. The EPA imposed regulations in the 1970s upon what it calls asbestos, that is, any asbestos mineral fibers of a size and shape that could harm the lungs. These minerals are harmless if you eat them or rub them on your skin.

EPA regulations protect workers from severe and chronic exposure to asbestos dust in the air. They helped end some scandalous, deadly workplace situations. They also nearly ended all the fairly safe uses of asbestos.

The flap in Seattle involved crayons, which kids are likely to eat. Crayons are commonly made with the mineral talc in them, but the stuff the crayon makers used wasn't pure. The system that's supposed to certify industrial ingredients broke down. It seems that the crayon maker and talc producers operated in a slipshod way that might have put their workers at risk.

But kids are not harmed by eating crayon wax with a little tremolite in it. The newspaper applied a medical standard to a regulatory incident. Seattleans were never in danger, and they should not have worried.

Who Worries About Asbestos?

Builders worry about asbestos because severe, chronic exposure to asbestos dust in the air (now long outlawed in civilized nations) is a clear health hazard. Workers who disturb old asbestos may have exposures that are severe, but not chronic. Nevertheless, they are right to minimize their risk with special suits and procedures. Besides, businesses are fined for ignoring regulations.

Regulators worry about asbestos because the statistics suggest a few extra deaths due to lung disease across large populations. The law requires them to quantify this small extra average risk. Nevertheless, the risk for someone without severe and chronic exposure is extremely small, on the order of 1 in a million in a lifetime. This is similar to the risk of radon exposure.

Ordinary people may or may not worry about asbestos. The standard advice to those with asbestos in their building is to leave it alone unless it is degraded and creating dust. Even then, the exposure is far short of that shown to cause disease in asbestos workers. But there's no sense in letting such a problem fester.

Geologists don't worry about asbestos. The minerals they encounter in the field are harmless.

PS: Workers who were exposed to lots of asbestos dust for many years have a small, but statistically significant extra risk of lung cancer if they smoke. The Memorial Sloan-Kettering Cancer Center has a tool that calculates that risk. Plug in some numbers and see the difference asbestos makes.

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