Does melanin protect your skin from cigarette smoke chemicals?

This study looks at whether the amount of melanin in your skin changes how much nicotine from thirdhand smoke gets into your body. Researchers will measure nicotine in blood and urine after skin exposure. The goal is to understand how skin pigment affects chemical uptake, not to treat any disease. Healthy nonsmokers aged 18-50 with very light or very dark skin can join.