Second-hand tobacco smoke is bad for everyone. But some people may be more susceptible to its insidious effects than others.
A U.S. study found that black children in the United States had far higher levels of tobacco's toxic chemicals in their blood and hair than white children who were exposed to similar levels of second-hand smoke.
In particular, the researchers took blood and hair samples from the racially mixed group of 220 asthmatic children who were exposed to at least five cigarettes a day in or around the home.
They measured for levels of cotinine -- a breakdown product of nicotine -- which is a standard scientific test for gauging contact with second-hand smoke.
The results revealed that the blood levels of cotinine were 32 per cent higher in the black children, compared with the white youngsters. Hair samples showed an even more dramatic difference: it was 400 per cent greater in blacks than whites.
The researchers are not sure why blacks had elevated cotinine levels. But Stephen Wilson, who led the study at the Cincinnati Children's Hospital Medical Center, speculated that black children may process environmental tobacco smoke in a different fashion than their white counterparts.
For instance, blacks may be less efficient at getting rid of the chemicals from their bodies. That could mean the harmful substances build up, Dr. Wilson said.
The results of the study, published in the journal Chest, may help explain why black children suffer from higher rates of tobacco-related disorders, such as asthma, sudden-infant death syndrome and low birth weight.