What Is Asbestos?

Asbestos has long been suspected as a health threat to humans, because the fibers can be inhaled and are difficult to remove from the lungs. Significant exposure to any type of asbestos will increase the risk of lung cancer, mesothelioma and nonmalignant lung and pleural disorders, including asbestosis, pleural plaques, pleural thickening, and pleural effusions.This conclusion is based on observations of these diseases in groups of workers with cumulative exposures ranging from about 5 to 1,200 fiber-year/mL.Such exposures would result from 40 years of occupational exposure to air concentrations of 0.125 to 30 fiber/mL.

Diseases from asbestos exposure take a long time to develop.Most cases of lung cancer or asbestosis in asbestos workers occur 15 or more years after initial exposure to asbestos.Tobacco smokers who have been exposed to asbestos have a “far greater-than-additive” risk for lung cancer than do nonsmokers who have been exposed, meaning the risk is greater than the individual risks from asbestos and smoking added together. The time between diagnosis of mesothelioma and the time of initial occupational exposure to asbestos commonly has been 30 years or more.Cases of mesotheliomas have been reported after household exposure of family members of asbestos workers and in individuals without occupational exposure who live close to asbestos mines.

Long and thin fibers are expected to reach the lower airways and alveolar regions of the lung, to be retained in the lung longer, and to be more toxic than short and wide fibers or particles.Wide particles are expected to be deposited in the upper respiratory tract and not to reach the lung and pleura, the sites of asbestos-induced toxicity.Short, thin fibers, however, may also play a role in asbestos pathogenesis.Fibers of amphibole asbestos such as tremolite asbestos, actinolite asbestos, and crocidolite asbestos are retained longer in the lower respiratory tract than chrysotile fibers of similar dimension.

Please Note:

• When asbestos fibers are inhaled, most fibers are expelled, but some can become lodged in the lungs and remain there throughout life. Fibers can accumulate and cause scarring and inflammation.Enough scarring and inflammation can affect breathing, leading to disease.
• People are more likely to experience asbestos-related disorders when they are exposed to high concentrations of asbestos, are exposed for longer periods of time, and/or are exposed more often.
• Inhaling longer, more durable asbestos fibers (such as tremolite and other amphiboles) contributes to the severity of asbestos-related disorders.
• Exposure to asbestos, including tremolite, can increase the likelihood of lung cancer, mesothelioma, and non-malignant lung conditions such as asbestosis (restricted use of the lungs due to retained asbestos fibers) and changes in the lung lining.
• Changes in the lining of the lungs (pleura) such as thickening, plaques, calcification, and fluid around the lungs (pleural effusion) may be early signs of asbestos exposure.These changes can affect breathing more than previously thought. Pleural effusion can be an early warning sign for mesothelioma (cancer of the lining of the lungs).
• Most cases of asbestosis or lung cancer in workers occurred 15 years or more after the person was first exposed to asbestos.
• Most cases of mesothelioma are diagnosed 30 years or more after the first exposure to asbestos.
  Mesothelioma has been diagnosed in asbestos workers, family members, and residents who live close to asbestos mines.
• Health effects from asbestos exposure may continue to progress even after exposure is stopped.
  Smoking or cigarette smoke, together with exposure to asbestos, greatly increases the likelihood of lung cancer.