Higher concentrations of the color pigment in skin and hair may be placing darker-pigmented smokers at increased susceptibility to nicotine dependence and tobacco-related carcinogens than lighter-skinned smokers, according to scientists.
"We have found that the concentration of melanin is directly related to the number of cigarettes smoked daily, levels of nicotine dependence, and nicotine exposure among African Americans," said Gary King, a biobehavioral health professor at Penn State.
Previous research shows that nicotine has a biochemical affinity for melanin, the color pigment in skin and hair, King said. This association could result in an accumulation of the addictive agent in melanin-containing tissues of smokers with greater amounts of skin pigmentation.
"The point of the study is that, if in fact nicotine does bind to melanin, populations with high levels of melanin could indicate certain types of smoking behavior, dependence, and health outcomes that will be different from those in less pigmented populations," King said. "And the addiction process may very well be longer and more severe."
The team's findings appear in the June issue of the journal Pharmacology, Biochemistry and Behavior.
To investigate the factors linking tobacco use, nicotine exposure, and skin pigmentation, the researchers recruited 150 adult African-American smokers from three sites in inner city Harrisburg during summer 2007. Participants provided researchers with the average number of cigarettes smoked each day and answered a questionnaire that measured nicotine dependence, the Fagerstrom Test of Nicotine Dependence.
Researchers also measured the smokers' cotinine levels. Cotinine is a metabolic byproduct of nicotine that can be used as a biomarker for tobacco use. King and colleagues surmise that nicotine's half-life and tobacco toxicants might be extended because of the accumulation of melanin-containing tissues.
The study findings could have health implications for African-American smokers, who tend to have darker skin, are disproportionately burdened with tobacco-related diseases, and report greater difficulty quitting smoking, King said.
Previous studies indicate that, even though African-Americans smoke fewer cigarettes than some other groups, they have a higher intake of nicotine from each cigarette.
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