The hazard, exposure, and risks associated with asbestos fibers have been explored and debated for many years. Human evidence suggests an association between exposure to asbestos and asbestosis, lung cancer, and mesothelioma, although the lack of consistent information on fiber type, size, and exposure concentrations and duration limit our ability to establish causal relationships between exposure and disease in some cases. While uncertainties remain in our ability to consistently and accurately quantify asbestos risk to humans, progress has been made in characterizing those key factors, namely hazard and exposure, that are critical to an assessment of health risk.
Because asbestos is a natural material, there will always be some background or ambient exposure to humans. Although mining and commercial applications have diminished in some parts of the world, asbestos continues to have commercial applications, and hence, there remains exposure potential from these sources. Chrysotile and amphibole asbestos are the types most commonly used and hence studied experimentally, and it has become increasingly clear that they differ with respect to toxicity and disease potential. This has been demonstrated in animal models, which appear to be reflective of the human situation as well.
Progress on a number of fronts has led to general scientific consensus on the following: (1) amphibole fibers (which tend to be relatively long and thin) are a more potent risk factor for the development of mesothelioma and, to a lesser degree, lung cancer than are chrysotile fibers (which tend to be relatively short and wide); (2) longer, thin fibers are more pathogenic and there appear to be fiber size thresholds below which asbestos fibers do not pose any threat; and (3) those animal studies in which high exposure concentrations resulted in lung overloading are not considered relevant to humans.
Analysis of the epidemiological literature supports some common patterns including:
(1) for occupational and industrial exposures, the weight of evidence does not consistently support causal relationships between asbestos exposure and onset of pulmonary disease, some studies showing associative relationships but others showing no relationship between exposure and disease onset; and (2) chrysotile alone, uncontaminated by other fiber types, particularly amphiboles, does not appear to be a risk factor for mesothelioma, as once thought.
Advances in risk assessment methodology and analytical techniques, together with reevaluation of historical data, reveal that the current Environmental Protection Agency (EPA) approach for risk assessment of asbestosis is not in step with current scientific consensus, particularly for chrysotile fibers. In recent years, new knowledge about how asbestos risk can be more accurately and quantitatively determined has been generated. There is thus a scientific basis for adoption of these methods by regulatory agencies, including the EPA. While occupational exposures to asbestos remain and should be vigilantly monitored, there appears to be no compelling scientific evidence that ambient exposure to chrysotile asbestos poses a significant health risk.
We all know we need the oxygen in the air to live, but unless we experience breathing difficulties, most of us rarely think about our lungs at all.
The lungs are complex organs, considered far more complicated than the heart. They not only take the oxygen from the air and send it into the bloodstream for delivery throughout the body, but the lungs filter out substances like dust, pollen, viruses, and bacteria from the air we breathe. They are also responsible for eliminating waste from the bloodstream. It is clear lung health is important, and October has been designated Healthy Lung Month in recognition of this fact.
If all types of lung disease are combined, it is the 3rd highest cause of death in the United States. Over 35 million Americans live with an ongoing lung disease like asthma or chronic obstructive pulmonary disease (COPD). Lung disease is the cause of 1 in 7 deaths annually in this country.
Unfortunately, it can be easy to overlook early signs of lung disease. At first, many people simply realize they do not have much energy. But as the lung condition worsens, other symptoms become more apparent. Trouble breathing, shortness of breath, reduced ability to exercise, feeling like you are not getting enough air, a chronic cough, coughing up blood or mucus, or pain when inhaling and exhaling, are among the signs of lung disease.
Common lung conditions include:
* Asthma, which affects 20 million Americans. It causes inflammation and swelling of the airways in the lungs. The narrow airways limits the flow of air in and out of the lungs, causing wheezing, coughing, tightness in the chest, and difficulty breathing.
* COPD, which includes emphysema and chronic obstructive bronchitis. Both conditions cause inflammation of the bronchial tubes that carry air to the lungs. This leads to thickening and scarring of the lining of the bronchial tubes and the production of excess mucus, making breathing difficult. COPD is the 4th leading cause of death in the United States.
* Lung cancer, now the leading cause of cancer deaths in American women, is characterized by the abnormal, uncontrolled growth of malignant lung cells.
These cells invade and destroy normal cells in nearby tissues and can spread to other parts of the body.
Fortunately, the risk of developing lung disease can be reduced. First, if you are a smoker, quit. Whether a smoker or a non-smoker, everyone should try to avoid second-hand smoke.
Second, eating a healthy diet, rich in fruits and vegetables, lowers the risk of cancer. Drinking plenty of water helps to replace moisture lost when we exhale, keeping the lung tissue moist and healthy.
Exercise is also important for healthy lungs, stimulating the blood flow required for the lungs to function optimally.
Lung health also benefits from getting vaccinated against the flu every year. Influenza (and pneumonia, often a complication of the flu), damages lung tissue and leads to a number of adverse health effects.
In addition to the above, avoiding environmental hazards such as asbestos and radon is also important in protecting lung health. Protective clothing and a face mask are required for anyone working in a job that entails exposure to asbestos. Radon in the home can be measured with a test kit to determine if remediation is advised.
The Central Connecticut Health District, serving the towns of Berlin, Newington, Rocky Hill, and Wethersfield, sponsors a number of flu shot clinics where pneumonia shots are also available. The Health District also sells low-cost radon test kits. For further information about flu clinics, radon kits, and other public health concerns, contact the Health District at 860-721-2822 (www.ccthd.org). Specific information about lung health and lung disease is available through the American Lung Association at 1-800-548-8252 (www.lungusa.org) and the National Women's Health Information Center at 1-800-994-9662 or 1-888-220-5446 for the hearing impaired (www.4women.gov).
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