How Asbestos Exposure Happens — and Why It Takes So Long to Show Up
Asbestos is, in OSHA's words, "the name given to a group of naturally occurring minerals that are resistant to heat and corrosion." It includes chrysotile, amosite, crocidolite, tremolite, anthophyllite and actinolite, along with any of these materials that have been chemically treated or altered (OSHA). The fibers are too small to see. Disease follows from breathing them in. OSHA describes a "buildup of scar-like tissue in the lungs called asbestosis," a loss of lung function that "often progresses to disability and death." It also states that asbestos causes lung cancer and mesothelioma.
The EPA explains that fibers are released when asbestos-containing material is disturbed "during product use, demolition work, building or home maintenance, repair, and remodeling" (EPA). OSHA states that heavy exposures tend to occur in construction and ship repair, particularly when asbestos materials are removed. It adds that workers are also likely to be exposed when asbestos products are manufactured and during automotive brake and clutch repair.
The NCI's history explains why so many diagnoses today trace back to older work. Use of asbestos "increased greatly during World War II." Shipbuilding used it "to insulate boilers, steam pipes, and hot water pipes," and the construction industry used it for insulation, roofing, fireproofing and cement. NCI names shipbuilding trades, asbestos mining and milling, manufacturing of asbestos textiles and other asbestos products, and insulation work in the construction and building trades. It adds that demolition workers, drywall removers, asbestos removal workers, firefighters and automobile workers may also be exposed (NCI). The site's page on occupational asbestos exposure goes trade by trade.
Not all exposure happened on the job. NCI reports "some evidence that family members of workers heavily exposed to asbestos face an increased risk of developing mesothelioma," which it attributes to fibers carried home "on the shoes, clothing, skin, and hair of workers." It also notes that disease has been found in people with only brief exposures.
The practical consequence of that long delay is that many people never connected a decades-old job to a cough that started last year, and building an exposure history often means reconstructing work that ended a generation ago.