Background exposure to asbestos
Asbestos is present in extremely low levels in soil, water and air. Although nearly everyone is exposed to asbestos at these background levels, this type of asbestos exposure carries relatively low risk of developing illness. Many people live in homes built with asbestos products, or work or go to school in buildings where asbestos products were used in construction. As long as the asbestos-containing materials are not sanded, scraped, filed, cut, or otherwise disturbed or removed, the asbestos fibers are less likely to escape and the hazard from them is reduced.
| Building materials and home products that may contain asbestos include: | |
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Carpet underlays Acoustic tiles Acoustic plaster Floor tiles Heat cement Roofing felt Roofing paper Lap seal Limpet spray Artificial fireplaces and materials Firebrick Patching and spackling compounds Pipe and duct insulation Vinyl wallpaper Pipe covering Pipe insulation Joint compounds Fake snow Perlite Corrugated asbestos sheet Troweled coating US Gypsum spray Wire mesh blanket Pot holders and ironing board pads |
Flame-proof oven mitts Toaster insulation Electrical wire insulation Textured paints Furnaces and furnace door gaskets Gypsum board and sheetrock Gypsum spray Vinyl gypsum adhesive Patching plaster Asbestos cement Furnace cement Weld-on cement One-coat cement Fiber cement Roofing cement High temperature cements Waterproofing Tar paper Mastic adhesives Insulation blankets Insulation board Mineral wool |
If a person lives or works in a structure in which one or more of these or other asbestos-containing products have been disturbed or removed, the risk of asbestos exposure rises. Removal of products that contain to asbestos should be done only by workers trained in asbestos removal.
Types of work and situations with high exposure to asbestos People who develop asbestos related diseases have usually had regular and perhaps frequent asbestos exposure, either through handling as part of their work, or living or working in a building where asbestos-containing materials have been disturbed by construction or renovation.
| Certain kinds of work involve high exposure to asbestos. These include: | |
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asbestos mining and milling manufacture of asbestos tiles manufacture of asbestos fabrics shipbuilding trades insulation work in construction electricians plasterers pipe fitters railroad workers |
manufacture of brake linings building demolition drywall installation drywall removal other asbestos removal firefighting asbestos tile setters boiler workers aluminum plant workers |
Ship construction involves many kinds of materials that contain asbestos. Shipyard workers often worked in closed spaces with material that released large quantities of asbestos fibers into the air. In Southern California, the Long Beach Shipyard (also called the US Naval Dry Docks and the Terminal Island Naval Shipyard), the San Diego Naval Shipyard, and NASSCO have employed thousands of workers in the shipbuilding trades, including pipe fitters, boilermakers, electricians, welders, machinists, filers, polishers, sanders, buffers, heat treaters, maintenance workers, engineers, draftsmen, and others.
People who have worked in shipbuilding in any capacity, even for a matter of weeks or months, at any time in their lives, are at increased risk for developing mesothelioma. They should tell their healthcare providers about their exposure.
9/11 and the North Tower: Another Generation of Mesothelioma
The attacks on the World Trade Center in 2001 created a new asbestos exposure hazard. The North Tower was constructed between 1970 and 1972 and asbestos, principally chrysotile, was used as fireproofing up to the 40th floor. Asbestos was not used beyond that point because it was recognized as a significant health hazard. Fireproofing was accomplished on the North Tower's upper floors with other materials. Although some of the asbestos from the first 40 stories had been removed over the preceding 30 years, hundreds of tons remained on 11 September 2001. When the North Tower collapsed an estimated 2000 tons of asbestos fibers were blasted into the air. Those with the greatest exposure were firemen, policemen, construction workers, paramedics, and volunteers who worked at Ground Zero.
Because of its known potential as a carcinogen asbestos immediately became a major health concern. The US Environmental Protection Agency collected thousands of samples of airborne and settled dust and analyzed them for asbestos content. Researchers from Mt Sinai School of Medicine reviewed the efforts to test for asbestos in a 2004 article in Environmental Health Perspectives. More than 10,000 ambient air samples from lower Manhattan were tested for asbestos using phase-contrast light microscopy (PCM) to identify fibers › 5 µm in length; more than 8,000 of these samples were also examined by transmission electronic microscopy (TEM) to identify fibers of 0.5 µm in length. These extremely short fibers cannot be filtered by the lungs when inhaled, and become deeply embedded in lung tissue, where they have the greatest potential to initiate cancers.
Most of the elevated asbestos levels in air were observed in the earliest days after September 11. Air samples showed that asbestos levels were initially elevated but fell to within U.S. EPA standards after the first few days. Asbestos was also found in settled dust at Ground Zero in concentrations ranging from 0.8 to 3.0%. Asbestos was found in dust in nearby apartments, sometimes at higher levels than in the outside environment. Because some residents had prolonged exposures to uncleaned apartments, these indoor exposures may have added significantly to ambient exposures.
Eight-hour time-weighted average asbestos exposures to workers were not above the Occupational Safety and Health Administration standard of 0.1 fiber/cm3. Nonetheless workers at Ground Zero, most of whom did not wear respirators or other protective equipment, experienced repeated short-term peak exposures, inhaling asbestos fibers each time they disturbed asbestos-containing rubble.
Additional asbestos exposure increases the risk for mesothelioma, and a higher incidence of mesothelioma will likely occur in the population who worked at Ground Zero and who lived and worked in lower Manhattan. Given the disease's pattern of extremely slow development, it these cases of mesothelioma may not be identified for decades.
Risk to family members of asbestos workers
Family members of a worker heavily exposed to asbestos are at higher risk for illness. Their risk comes from asbestos exposure to fibers brought into the home on the worker's hair, clothing, and shoes. Federal and some state laws now require people working with asbestos to take safety measures to prevent the fibers being carried on them. Depending on the nature of their work and their exposure, workers may be required to shower and change their clothes before leaving work, store their own clothes in a separate part of the workplace, or wash work clothes separately at home.
Risks in asbestos removal and building demolition
In the course of removing asbestos from homes and workplaces, the asbestos-containing materials are likely to be sawed, pounded, pried loose, sanded, and otherwise disturbed, in ways that release asbestos fibers into the air, where they can be inhaled. Demolition of a building presents even greater risks of creating airborne asbestos fibers. Asbestos removal should only be done by trained workers who adhere to OSHA safety standards for themselves and the building's occupants.
Even brief asbestos exposure can be dangerous
Although the highest risk of developing mesothelioma comes from regular and prolonged exposure to asbestos, some people have developed the disease after only very brief exposure. Asbestos fibers which lodge in lung tissue and are not expelled continue to damage the tissue as long as they stay there, as the mesothelioma grows slowly and silently. Symptoms may not appear for 15 to 40 years after exposure.
