Blacks and others with darker skin might be at greater risk for tobacco addiction than whites and those with lighter skin because the greater the amount of melanin, the coloring pigment in skin, the more nicotine appears to be stored, according to preliminary findings published in the journal Pharmacology, Biochemistry and Behavior, the New York Times reports. For the study, lead researcher Gary King, a professor of biobehavioral health at Pennsylvania State University, looked at 150 black smokers and measured their levels of melanin and cotinine, a byproduct of nicotine. They also surveyed the participants to determine the level of their smoking habit.

Those with the most melanin were found to smoke the most and have the most cotinine in their system. They also had the highest level of dependence on tobacco. The findings might indicate why some people are more affected by nicotine than others.