Researchers found that after the U.K., Australia, and Canada banned the terms as deceptive, there was a dip in the number of people who mistakenly believed that cigarettes marketed as "light" or "mild" carried fewer health risks.
However, the decline was temporary, the investigators report in the journal Addiction.
And in the U.K., misperceptions were consistently higher versus the other two countries, as well as the U.S. -- where, at the time of the study, no such ban was in place.
"The findings from this study confirm our earlier work showing that merely removing the terms 'light' and 'mild' from cigarette packs is insufficient to change people's beliefs that those products are safer," lead researcher Dr. Hua-Hie Yong said in an email.
To really clear up misperceptions, more steps are needed, according to Yong, of the Cancer Council Victoria in Melbourne, Australia.
"Light" cigarettes are designated as such because they deliver less nicotine and lower levels of toxic chemicals -- or "tar" -- when the smoke is measured by a machine.
In real life, though, studies show that smokers inhale comparable amounts of nicotine and chemicals regardless of the brand. And critics have long charged that tobacco products dubbed "light" or "mild" confuse people into thinking there are fewer health risks.
In response, the European Union and Brazil put bans on those terms in 2003, and other countries have since followed suit.
A U.S. law that bars the words "light," "low tar, and "mild" from tobacco products went into effect almost exactly one year ago.
For the new study, Yong's team looked at results from an international survey done annually between 2002 and 2009 in Australia, Canada, the U.K., and the U.S.
The surveys involved a total of 21,600 smokers who were asked the extent to which they agreed with statements like, "Light cigarettes are less harmful than regular cigarettes."
Overall, the study found that shortly after "light" bans went into effect, misperceptions about the cigarettes generally dipped in Australia, Canada, and the U.K.
However, the false beliefs began to creep back in within a couple years.
In the U.K., which banned the terms in 2003, misperceptions remained persistently higher than in other countries, including the U.S. On average, U.K. smokers had a higher level of agreement with statements extolling the advantages of light cigarettes over regulars.
It's not clear why that is, according to Yong.
But one reason, the researchers speculate, could be a U.K. law of the same time period that forced tobacco makers to lower the tar "yield" in cigarettes. That, Yong said, might have drawn smokers' attention to the tar issue, and reinforced the belief that lower tar means a safer cigarette.
After the U.S. ban went into effect last year, some health advocates, including the American Lung Association (ALA), applauded the move but said that deceptive packaging remains a problem.
Some manufacturers sell light and regular cigarettes in packages of different colors. And allowable terms like "smooth" and "silver," critics say, may still mislead consumers.
The current findings underscore the fact that no single step is enough to combat years of misleading tobacco marketing, according to Erika Sward, director of national policy and advocacy at the ALA.
"This is one more piece of information that points to a need for a big-picture, comprehensive solution," Sward said in an interview.
One change that could help, according to Sward, would be an end to the "color-coding" of cigarette packs that lets smokers know which ones are "light" or regular.
She said the ALA hopes that the Food and Drug Administration -- only recently given the power to regulate tobacco products -- will conduct research to see whether package coloring affects consumers' choices.
Australia recently introduced legislation to become the first country in the world to require all tobacco products to be sold in "plain packaging." The tobacco industry has come out against such a move, saying there's no evidence it would make a dent in smoking rates.
Both Yong and Sward pointed to a need for ongoing public education.
Many smokers, Yong said, "continue to believe that some cigarettes are safer than others based on the fact that they taste 'milder' or it has a lower tar yield, and this false belief will keep them smoking instead of quitting."
"There is no safe cigarette on the market," Sward said. And if smokers want to do something for their health, she added, they can seek help in quitting -- from their doctors, the ALA, or the government-sponsored quit line 1-800-QUIT-NOW.
By Amy Norton
Addiction, online June 9, 2011.
Last Updated: 2011-06-23 16:58:16 -0400 (Reuters Health)
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