Philadelphia Inquirer Friday, March 21, As Liggett agrees to new warnings, a study questions effectiveness Research finds many adolescents don't read labels. Nicotine is found to be the key obstacle to quitting. By Robert S. Boyd INQUIRER WASHINGTON BUREAU WASHINGTON Will tougher cigarette warnings work? The Liggett Group's agreement to mark its packages with a warning that cigarettes are addictive comes after 30 years of increasingly somber cautions about the danger of tobacco. During that time, cigarette smoking has dropped by half among adult males and by onethird among adult women. But it is increasing sharply among teenagers, when the habit is usually picked up. In fact, teenage smoking increased by 30 percent from 1991 to 1995, according to a study published yesterday by the Stanford University School of Medicine. ``Sizable proportions of adolescents are not seeing, reading and remembering cigarette warning labels,'' said the study, which surveyed 1,700 high school freshmen in San Jose. ``Knowledge of warning labels was not associated with subsequent decreased smoking.'' The labels now say that smoking causes cancer, emphysema and other diseases, but do not mention addiction. Researchers say that three out of four people who start smoking become confirmed addicts, and that 90 percent of those who try to quit each year fail. A major part of the reason is that nicotine is as addictive as cocaine and heroin, and even more habitforming than alcohol, according to scientists who study addiction. Using modern electronic brainscanners, researchers can see how chemicals in tobacco smoke permanently change the way brain cells, called neurons, communicate with one another. The changes make it extremely difficult and often impossible for people to quit. ``Nicotine meets all the criteria of a highly addictive drug,'' said Jack Henningfield, an expert on drug and tobacco addiction at Penny Associates in Baltimore. Until a halfcentury ago, tobacco was considered neither harmful nor addictive. By the end of World War II, it was widely accepted that cigarettes were unhealthful, but not nearly as bad as hard drugs. Smokers called them ``coffin nails'' as they cheerfully puffed away. But during the 1970s, researchers began to unravel nicotine's addictive powers. In 1988, President Ronald Reagan's surgeon general, C. Everett Koop, issued a 618page report declaring that ``cigarettes are addicting in the same sense as are drugs such as heroin and cocaine.'' Koop ordered stiffer warning labels on cigarette packs. Smoking began dropping among adults, but kept rising among adolescents. Last year, President Clinton authorized the Food and Drug Administration to regulate nicotine as a dangerous substance. The FDA's proposed rules limiting access to minors are being challenged by a coalition of tobacco companies in federal court in North Carolina. The companies, with the exception of Liggett, deny that smoking is addictive, and point to the millions of Americans who have quit. In its settlement yesterday, Liggett, the maker of Chesterfield and other brands, agreed to add a prominent warning to each cigarette pack acknowledging that smoking is addictive and causes health problems, including lung cancer. A colorless, oily liquid composed of carbon, hydrogen and nitrogen, nicotine itself does not cause disease. Scientists say it is the other toxic substances in tobacco smoke chiefly tar and carbon monoxide that lead to cancer of the lungs, throat and other organs. But nicotine is indirectly responsible for the damage because it makes it so hard for smokers to quit. According to Henningfield, 5 milligrams of nicotine a day is enough to cause addiction. Each cigarette delivers about 1 milligram of nicotine into the bloodstream of a smoker. Within 20 seconds after it hits the bloodstream, nicotine reaches the brain and is distributed among the trillions of neurons that govern thinking, memory, perception and emotion. At that point, it stimulates the production of a chemical messenger, called dopamine, that helps pass signals from one neuron to another. This excess of dopamine produces the pleasurable sensations that accompany smoking, or the ``high'' that goes with cocaine.