"Cigarettes are finely tuned drug delivery devices, designed to perpetuate a tobacco pandemic," said Howard Koh, an associate dean for public health practice who worked on the analysis. "Yet precise information about these products remains shrouded in secrecy, hidden from the public."
One out of every five deaths in the U.S. is linked to smoking. It is estimated that nine hundred thousand Americans will become addicted in 2007.
The National Cancer Institute and a non-profit anti-smoking group paid for the study. Researchers are presenting their findings later Thursday at Harvard.
Massachusetts is one of three U.S. states to require tobacco companies to submit information about nicotine testing according to its specifications and the only state with data going back to 1997. Harvard did a more in-depth analysis of the state's data and looked at one additional year.
The health department study released last October examined nicotine levels in more than 100 brands over a six-year period. The study showed a steady climb in the amount of nicotine delivered to smokers' lungs and said the higher nicotine levels made it easier to get hooked on cigarettes and harder to quit.
Gregory Connolly, head of the Tobacco Control Research Program at the Harvard School of Public Health, said the increase found in Harvard's study is due primarily to an increase in nicotine in the raw tobacco used in the cigarettes.
"There's something going on either with the type of tobacco they're using or the addition of more nicotine to the reconstituted tobacco. We just don't know," Connolly said.
He also said the findings call into question whether the tobacco industry is living up to its 1998 agreement with states that it would launch a campaign to reduce smoking by young people. "If that same industry turns around and advances the availability of nicotine in the product, you may not get fewer kids smoking," he said.
Cigarette manufacturers disputed the findings of both studies. Cigarette manufacturer Philip Morris said data reported to the state by the company shows nicotine yields for Marlboro cigarettes were the same in 2006 and 1997.
The company said the data reflect random variations in cigarette nicotine yields, both upward and downwards, and that variations are not consistent.