Asbestos is the generic name for several fibrous minerals that are found in nature. Very long and thin fibers are bundled together to make asbestos. First used as a coating for candlewicks by the ancient Greeks, asbestos was developed and manufactured in the twentieth century as an excellent thermal and electrical insulator. The physical properties that give asbestos its resistance to heat and decay have long been linked to adverse health effects in humans. Asbestos is found in mostly older homes and buildings, primarily in indoor insulation.
Asbestos tends to break into microscopic fibers. These tiny fibers can remain suspended in the air for long periods of time and can easily penetrate body tissues when inhaled. Because of their durability, these fibers can lodge and remain in the body for many years. No "safe" exposure threshold for asbestos has been established, but the risk of disease generally increases with the length and amount of exposure. Diseases associated with asbestos inhalation include asbestosis (scarring of the lungs), lung and throat cancers, malignant mesothelioma (a tissue cancer in the chest or abdomen), and nonmalignant pleural disease (accumulation of bloody fluid around the lungs).
In May 2003 the CDC released its sixth annual Work-Related Lung Disease Surveillance Report 2002. The report notes that 1,265 people died in 2002 from asbestosis. (See Figure 8.6.) This value is up from less than 100 recorded in 1968. In total, 10,914 people have died from asbestosis between 1990 and 1999. The vast majority of the deaths have occurred among white men aged 55 and older. Most were plumbers, pipe fitters, and steamfitters. Construction accounted for, by far, the greatest proportion (24.6 percent) of asbestosis deaths; second was ship/boat building and repairing (6.0 percent). Death from asbestosis usually occurs only after many years of impaired breathing.
Asbestos was one of the first substances regulated under section 112 of the Clean Air Act of 1970 (CAA; PL 91-604) as a hazardous air pollutant. The discovery that asbestos is a strong carcinogen has resulted in the need for its removal or encapsulation (sealing off so that residue cannot escape) from known locations, including schools and public buildings. Many hundreds of millions of dollars have been spent in such cleanups.
Under the CAA, asbestos-containing materials must be removed from demolition and renovation sites without releasing asbestos fibers into the environment. Among other safeguards, workers must wet asbestos insulation before stripping the material from pipes and must seal the asbestos debris in leak-proof containers while still wet to prevent the release of asbestos dust. The laws of most states have specific requirements for asbestos workers.
A number of legal convictions have resulted from improper and illegal asbestos removal. In many cases the
Fluoridation growth, by population, 1940-2000
convicted companies had hired homeless people or teenagers to clean up asbestos without advising them that they were dealing with asbestos and without training them in proper handling methods. In response to those cases the Department of Justice and the EPA joined with the National Coalition for the Homeless to issue an advisory to be posted in homeless shelters around the United States. The advisory warns about the dangers of asbestos and cautions workers to be on guard for employers who offer work tearing out old asbestos without providing adequate notice, equipment, and training.
Some observers believe that asbestos poses less risk to humans than previously thought, and suggest that asbestos is less harmful than smoking, drug and alcohol abuse, improper diet, or lack of exercise. They contend that Americans can live safely with asbestos—given careful management procedures—and do not need to spend huge sums of money attempting to remove it completely. In fact, the EPA recommends that asbestos found in good condition be left alone, because "disturbing it may create a health hazard where none existed before."
According to the USGS Mineral Commodity Summaries, January 2004, there was no asbestos production in the United States in 2003. The last U.S. asbestos mine closed in 2002. Approximately 6,000 metric tons of asbestos were imported into the country during 2003. Canada supplied 96 percent of the imported asbestos. U.S. demand for asbestos peaked in the 1970s, when it reached 800,000 tons. By 2003 U.S. demand had dropped to 6,600 tons, a level not seen since the 1800s. Most (80 percent) of the asbestos consumed in 2003 was used in roofing products. Gaskets accounted for another 8 percent, followed by friction products with 4 percent.
World production of asbestos in 2003 was around 2 million metric tons, with Russia as the leading producer, followed by China and Canada. World production has dropped since it peaked in 1975 at 5 million metric tons. Growing pressure to ban asbestos around the world is expected to keep pushing markets downward.