Occupational lung disease is the number one work-related illness in the United States; rankings are based on frequency, severity, and preventability, and this group of serious disorders fills all three criteria. The diseases that fall under this category are caused by exposure, usually extended, to irritating or toxic substances that may cause acute or chronic respiratory ailments. Smoking, as noted in that section, can act synergistically to increase the severity of these diseases many-fold. In 1998, there were an estimated 17,315 lung cancer deaths attributable to inhalation of carcinogens in the workplace.
The major substances and the conditions they cause:
AsbestosThis substance was previously widely used as an insulator and fire retardant; virtually unburnable, it was viewed as an unqualified lifesaver until realization of the fact that, in the lung, its microscopic fibers are lethal. Asbestos causes lung cancer; mesothelioma, an otherwise rare cancer of the chest lining; and fibrosis of the lung (asbestosis), a progressive disease involving scarring of lung tissues. All have lengthy latency periods, ranging from ten to thirty years. Exposures have involved mining, construction and demolition, shipyards, tiling, electrical insulation, paving, and brake linings, among other industries and products. Over the years, many millions of workers have been exposed to asbestos.
According to the Division of Respiratory Disease Studies of the National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC), 8,761 deaths in the U.S. were attributed to asbestosis between 1979 and 1992, and the annual figure has risen steadily during that period. Deaths attributed to asbestosis numbered 959 in 1992; the greatest number were in Pennsylvania (100), followed by New Jersey (80).
Dusts from hemp, flax, and cotton processing cause byssinosis ("brown lung"), a chronic condition involving obstruction of the small airways, severely impairing lung function. An estimated 35,000 current and former textile workers have been disabled by byssinosis. Between 1979 and 1992, the condition caused 183 deaths; the largest number of these were in North Carolina.
Coal dust causes coal workers' pneumoconiosis ("black lung"), an obstruction of the small airways leading to disabling respiratory impairment. Today, an estimated 4.5 percent of coal miners are affected; about 0.2 percent have progressive massive fibrosis (scarring), the most severe form of the disease. Between 1968 and 1992, more than 59,000 deaths were attributed to black lung disease. Almost all of these deaths occurred in males. In 1992, Pennsylvania had the highest number of such deaths; West Virginia ranked a distant second.
Grain Dusts and Other Farm Hazards
An estimated five million agricultural workers in North America may be at risk of lung inflammation due to bacterial endotoxins found in various grains, according to studies reported in 1994. Other potentially dangerous substances to which such workers may be exposed include hair, feathers, animal dander, and bacteria and their spores; respiratory responses to these particles may be acute or chronic, resolving completely or resulting in permanent disability or even death.
A form of this substance known as free crystalline silica causes silicosis, a type of pneumoconiosis affecting workers in mines, foundries, blasting operations, and stone, glass, and clay manufacturing (including the production of plumbing fixtures). About 1.6 million workers are believed to have been exposed, and almost 60,000 are expected to suffer some degree of silicosis. Silicosis substantially raises the risk of other lung diseases, particularly tuberculosis, bronchitis, and emphysema.
According to NIOSH, the number of deaths attributed to silicosis between 1979 and 1992 was 4,882, and the annual total has been decreasing over the past two to three decades. In 1992, 255 deaths were attributed to silicosis.
Other agents, besides asbestos, encountered in industrial settings have been associated with lung cancer; they include arsenic, chloroethers, chromates, ionizing radiation, nickel, and polynuclear aromatic hydrocarbons.
Substances triggering allergic reactions may cause asthma attacks ("occupational asthma") in susceptible workers; the condition may account for as many as 15 percent of all newly diagnosed U.S. cases of asthma in adults, and it is the most prevalent occupational lung disease in developed countries. Such substances may also cause a condition known as hypersensitivity pneumonitis (lung inflammation). If exposure continues, it may lead to irreversible pulmonary fibrosis, a process that causes formation of fibrous tissue within the lungs and makes breathing progressively more difficult.
Many substances have been implicated in occupational asthma, including grain dusts, fungi, metals, resins, animal proteins, plant products, dyes, drugs, and a variety of chemicals. Among the many affected categories of workers: bakers, animal handlers, pharmaceutical workers, food processors, carpenters, painters, insulation workers, cleaners, electronics workers, hairdressers, and health professionals.
Minority groups have been traditionally overexposed to occupational respiratory hazards. They are far less likely to hold managerial positions and are apt to be assigned to the "dirtiest" tasks in such industries as mining (coal, silica), textiles, demolition, and manufacturing involving hazardous materials (e.g., asbestos)-all of which have been associated with respiratory disease.
The U.S. Bureau of Labor Statistics reports, for example, that of 1.4 million textile and apparel machine operators (1994), African-Americans, 12.7 percent of our population, account for 21.8 percent; Hispanics, 8.9 percent of the population, account for 20.0 percent.
Similarly, it is estimated that of 2.7 million cleaning and building service jobs, 22.4 percent are held by African-Americans and 17.7 percent by Hispanics. These pursuits entail exposure to an array of noxious chemicals, as well as to maintenance systems that are often the source of biological contaminants associated with critical allergic reactions.
In Colorado and New Mexico, Native Americans have been disproportionately employed in uranium mines. That fact has been associated with an inordinately high rate of lung cancer, due to exposure to radon byproducts (radon results from radioactive decay of radium, which is in turn a decay product of uranium). Results of a 30-year study of such workers were reported in the American Journal of Public Health in 1995; elevated risks were documented for lung cancer (up to 6.9 times normal), tuberculosis, and pneumoconiosis, and the heightened risks persisted more than two decades after exposure ended.
FOR MORE INFORMATION
For More Information visit the Occupational Safety and Health Administration (OSHA) web site at http://www.osha.gov.
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