Smokers who pride themselves on successfully cutting back as a step toward quitting tobacco altogether may be caught in a haze of self-deception. New research shows smokers who slash their cigarette use by half quickly change the way they smoke to compensate for less exposure – ironically, in the process, often boosting their consumption of smoke, carbon monoxide, nicotine and other cancer-causing agents.
The findings hold important implications for smokers as well as the clinicians who are trying to help them quit.
“The human body really is a miracle. It knows when it is not getting what it’s used to, and it automatically does something about it,” says Karen Ahijevych, an associate professor of nursing and a member of The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute.
The findings appear in the April issue of Pharmacology, Biochemistry & Behavior.
Ahijevych and her research team studied 25 women over six days in three different situations: smoking their usual amount, restricted intake (50 percent) and increased intake (167 percent). Thirteen of the women were black and 12 were white. The women smoked their regular brands of cigarettes and researchers noted levels of carbon monoxide (CO) and cotinine in the participants’ blood before and after four of the cigarettes each day. Carbon monoxide reflects general exposure to hundreds of toxins and carcinogens in smoke while cotinine, a metabolite of nicotine, reveals how much nicotine has been absorbed over time.
The scientists also carefully observed the way the women smoked – scientists call it “smoking topography” – measuring such things as the number and size of the puffs per cigarette, the length of time between puffs and how much of the cigarette was smoked before it was extinguished.
Researchers discovered that, generally, when women smoked in a restricted environment, they took larger drags and smoked more of the cigarette before putting it out. In addition, when smoking fewer cigarettes, the women produced more CO in their exhaled air per cigarette, compared to when they smoked their regular number of cigarettes or increased use.
Higher CO and nicotine boosts were especially pronounced among women who were defined as efficient smokers – those who normally register high levels of cotinine per cigarette with regular smoking ( more than 20 nanograms per millileter of blood.)
“We were surprised at how much the very efficient smokers could increase their levels of CO and nicotine even further,” says Ahijevych. “And the interesting thing is that most of these women were totally unaware that they were changing the way they were smoking to make up for fewer cigarettes.”
There appeared to be differences in ethnicity as well, with black women registering higher percentage increases of carbon monoxide levels across all smoking situations, compared to whites. Ahijevych says this may be due to the fact that all of the black women smoked menthol cigarettes, and menthol smokers tend to inhale greater amounts of smoke because it is somewhat easier to take in, compared to non-mentholated smoke.