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WASHINGTON, Jun 23, 2003 (United Press International via COMTEX) -- Scientists may have put the last nail in the coffin on whether active smoking is linked to cancer, but what still remains unresolved is whether tobacco's unhealthful effects extend to other types of illness and whether secondhand smoke is as dangerous as suspected.
The smoking debate has been simmering for nearly 40 years, ever since the January 1964 release of the report by the U.S. Surgeon General's Advisory Committee on Smoking and Health. Issued under the authority of Dr. Luther L. Terry, it was a landmark document and one of the first to bring to public awareness the cigarette-smoking-to-cancer link. Congress adopted the Federal Cigarette Labeling and Advertising Act in 1965 and the Public Health Cigarette Smoking Act in 1969, which called for an annual report on the health consequences of smoking and mandated the now-familiar warning labels on cigarette packs.
Now, at the beginning of the 21st century, scientists still find themselves having to prove the dangers of active cigarette smoking and increasingly the health risks of environmental smoke.
"There is no controversy among the scientific community" on the effects on active and environmental smoke, Terry Pechacek, associate director for science at the Centers for Disease Control and Prevention's Office on Smoking and Health, told United Press International. "It's an established conclusion based on overwhelming wealth of data."
According to the CDC, tobacco use remains the leading preventable cause of death in this country. About 25 percent of American adults smoke and approximately 80 percent started smoking before age 18. Recent studies have shown that, each day, more than 5,000 American teenagers try their first cigarette. Tobacco use causes more than 440,000 deaths every year in the United States, resulting in an annual price tag of more than $75 billion in direct medical costs.
Smoking has been determined conclusively as a cause of lung cancer, the number one cause of death in America, the American Cancer Society reports, with an estimated 157,200 deaths expected in 2003 alone. What Americans seem not as well aware of is the long list of other diseases associated with active and secondhand smoke.
"Smoking is unequivocally and causally related to a variety of cancers and cardiovascular disease," Dr. David Burns, a member of the Society for Research on Nicotine and Tobacco and a professor of family and preventive medicine at the University of California, San Diego, told UPI. Scientists have proven active smoking is behind cancers of the throat, head and neck -- anywhere, Burns said, "where cigarette smoke comes into direct contact." It also has been linked to bladder and cervical cancer. "It may be that certain kinds of tissue that may be more vulnerable" to the carcinogens, he explained.
Dr. Adi Gazdar, a pathologist in oncology at the University of Texas Southwestern Medical Center in Dallas, explained even though cigarette smoke does not come into contact with some parts of the body directly -- the bladder, for example -- the carcinogens in cigarettes, such as benzene and vinyl chloride, are metabolized. These "metabolites can reach other organs," Gazdar told UPI, which could explain the connection between smoking and bladder cancer. It is possible metabolized carcinogens could be impairing other areas of the body, he said.
Cigarettes also have been linked conclusively to cardiovascular illnesses, including heart disease, heart attacks and stroke.
"The cardiovascular system is just exquisitely sensitive to something in the smoke, and it's probably not the nicotine," Stanton A. Glantz, a professor of medicine and director of the Center for Tobacco Control and Research Education at the University of California, San Francisco, told UPI. Nicotine is the chemical in cigarettes that hooks people, he said, but there are other substances damaging the blood vessels. Smoking raises the risk of heart problems, Glantz explained, by building up sticky plaque and reducing critical blood flow.
Still questions remain within the scientific community over the impact of environmental smoke. Glantz characterizes that debate in a different way.
"As far as I know, there's no legitimate scientist in the world who doesn't think secondhand smoke causes lung cancer and heart disease. There are a number of people paid by cigarette companies to say that it doesn't," he said. California has taken a leading role in the fight against environmental tobacco exposure by banning smoking in all public buildings, including smoking in bars.
"California has been a trend setter in these issues," Pechacek agreed.
These radical public policies seem to be working. Pechacek said CDC data compared environmental smoke exposure in 1991 to 1994 and then again in 1999 to 2000, after more stringent anti-public smoking bans -- such as no smoking in the workplace -- were implemented. The results showed a 75 percent decline among adults exposed to environmental smoke and 58 percent for children.
These findings, Pechacek said, are "primarily due to the change in public policies and the environmental changes protecting smokers from secondhand smoke. So there's been a substantial change." New York State and other states are considering similar laws to those in California. National data from the CDC also show environmental smoke causes 3,000 cases of lung cancer and over 35,000 heart attacks every year in the U.S., Pechacek said.
However, environmental tobacco exposure remains a huge public health problem and the intensity of the fight against it varies around the country. Glantz said this is due to "a 25-year-old campaign the PR companies run to confuse the issue on secondhand smoke."
Environmental or secondhand smoke came under severe criticism in the scientific world just last month when an article published in the May 17 issue of British Medical Journal challenged the notion environmental smoke was a health risk.
Researchers at the University of California, Los Angeles, and the State University of New York at Stony Brook, studied 118,094 adults in California. The subjects were enrolled in an American Cancer Society study in 1959 and followed until 1998. The study focused on 35,561 non-smokers who were married to individuals who smoked. These people were compared to non-smokers married to other non-smokers.
The findings suggested the risks of cardiovascular disease and lung cancer in the two groups -- non-smokers married to smokers and non-smokers married to non-smokers -- were about the same. The researchers wrote: "The results do not support a causal relation between environmental tobacco smoke and tobacco related mortality, although they do not rule out a small effect. The association between exposure to environmental tobacco smoke and coronary heart disease and lung cancer may be considerably weaker than generally believed."
However, the journal article also disclosed the study had been financed by the tobacco industry, and scientists blasted the research, calling its publication irresponsible.
"I think it is shameful the British Medical Journal published that study," Glantz said. He claimed the evidence to the contrary is overwhelming. "Thirty minutes (of secondhand smoke) just clobbers your blood in your blood vessels, for example."
Pechacek echoed that statistic: "Even 30 minutes of exposure showed an acute change" in the heart and blood vessels, he said.
Kenneth Warner, director of the University of Michigan Tobacco Research Network in Ann Arbor, said the study was flawed from the beginning because it was based on data collected during a time when smoking was permitted in all public areas. "So everyone was exposed to environmental smoke in the 1950s," Warner told UPI. "There's no debate whatsoever that environmental tobacco smoke causes lung cancer. There is debate over how much other death it causes."
Researchers also are exploring whether smoking is linked to breast cancer and breast cancer deaths. "The one area where there's a good hot argument right now is breast cancer," Glantz said. There are 212,600 new cases every year among women and men and 40,200 deaths, according to 2003 data from the American Cancer Society. Whether smoking, active or environmental, contributes to these figures is unclear.
"If you just look at the chemicals in smoke you would expect cigarette smoke to cause breast cancer," Glantz noted. The current theory, he said, is active smoking damages the ovaries, suppressing estrogen. High estrogen levels are linked to increased breast cancer risk. Despite reduced estrogen levels, women smokers still are exposed to the carcinogens. "We know the chemicals in smoke induce mammary tumors in animals," he said.
What continues to mystify scientists is some research suggests the breast cancer risk between active smokers and those exposed routinely to secondhand smoke is about the same, Glantz said. Women exposed to secondhand smoke are breathing in the carcinogens, but they are not experiencing the damage to the ovaries that would impair estrogen levels the way active female smokers are. "They're not getting the estrogen effect," he said. "They're just getting the cancer-causing chemicals."
Not all scientists agree and the research findings have been mixed. "I think with breast cancer, the evidence is weak," Gazdar said. "The risk is very slight or not quite proven yet. There are several factors that influence breast cancer."
As scientists volley their theories, Americans can be sure it does not matter what type of cigarette they smoke -- filtered, unfiltered, Menthol, regular or low-tar, they are all dangerous. "The risks are essentially identical with cigarettes of all tar values, filtered or unfiltered," Burns said. In fact, Menthol cigarettes might be even more harmful because its numbing effects can lead to deeper inhalation.
Puffing on a Marlboro or breathing in someone else's Virginia Slims both produce health consequences. Although the effects are never immediate, exposure to both active and environmental smoke has a likelihood of surfacing as health problems later in life.
"No cigarette is safe," Gazdar said. "Most cancers caused by cigarettes take many, many years" -- an average of 20 to 30. Quitting always can improve one's odds, but never starting is the best protection. "If you stop smoking, your risk goes down, but it never goes away," he cautioned. "It never goes down to the level of a non-smoker."
Copyright 2003 by United Press International.