Originally Released: April, 1999
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The same bacterial toxin that causes shock during severe bacterial infections and chronic bronchitis in some industrial workers has been found in cigarette smoke. University of Maryland researchers who made the discovery say it may explain why many smokers get chronic bronchitis.
In a study published in the March issue of CHEST, the journal of the American College of Chest Physicians, the researchers report that one pack of cigarettes contains almost one-half a milligram of endotoxin. "Smoking one pack of cigarettes a day gives the same endotoxin exposure as working in a dusty cotton mill for eight hours," says lead researcher Jeffrey D. Hasday, M.D., associate professor of medicine at the University of Maryland School of Medicine and director of the pulmonary outpatient clinic at the Baltimore VA Medical Center.
The toxin is a known cause of chronic bronchitis among workers in cotton mills, fish canneries, swine farms and other industrial sites.
The study is the first time that bacterial endotoxin has been found in cigarette smoke. The toxin, which enters the lungs of smokers and, to a lesser degree, the lungs of those who inhale second-hand smoke, is one of the more powerful known triggers of bronchial inflammation. "This may explain why cigarette smoke exposure makes asthma worse and causes chronic bronchitis," says Dr. Hasday.
The researchers used smoking machines to analyze the endotoxin levels in direct and second-hand smoke from research cigarettes and from cigarettes off the shelf.
"The endotoxin is part of the outer wall of Gram-negative bacteria," says Dr. Hasday. "It is difficult to eliminate and is very resistant to heat, allowing it to survive during tobacco processing, cigarette manufacturing and smoking."
Other causes of lung inflammation, like pre-existing asthma or even a cold, can increase the sensitivity to inhaled endotoxin, so that even the lower levels of endotoxin in second-hand smoke may have harmful effects in people already suffering from bronchial irritation," he says.
Dr. Hasday points to the study's findings as an argument for stronger regulation of smoking in the workplace. "Those whose job constantly exposes them to second-hand smoke, such as bartenders, are at increased risk for developing respiratory disease, even if they themselves are not smokers."
There are about 14 million cases of chronic bronchitis in the United States. About 3,000 people die of it each year at an annual cost of $24 billion. Symptoms include recurrent cough, production of sputum, chronic inflammation of the lung and oversecretion of mucous.
The study was funded in part by the American Lung Association of Maryland. Dr. Hasday is president of the Maryland Thoracic Society and a member of the board of directors of the American Lung Association of Maryland.
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