Parents may have one more reason to quit smoking.
A new study, presented Monday at the annual meeting of the Pediatric Academic Societies in Baltimore, finds that exposure to cigarette smoke in children and adolescents may lead to poorer test scores.
Researchers assessed logic and reasoning, math and reading skills in 4,399 children aged 5 to 16 using data gathered from 1988 to 1994. These test scores were compared to the amount of smoke each child had been exposed to, which was determined by measuring levels of a nicotine byproduct called cotinine.
"Children who had more exposure and had higher cotinine levels performed more poorly on all of the cognitive tests than the children who had the lower levels," says Kimberly Yolton, research associate at the Children's Environmental Health Center at Cincinnati Children's Hospital Medical Center, who conducted the research.
The biggest declines were seen in reading skills: Every five-unit increase in the level of cotinine corresponds with a five-unit decrease in reading scores. The effects were also strong for low levels of exposure.
Yolton estimates that more than 13 million children across the United States are exposed to levels consistent with the findings of this study and may be at risk.
Tobacco industry representatives were not immediately available for comment.
‘A Toxic Soup’
While the precise mechanisms behind this association are unknown, the ill effects of cigarette smoke exposure in children have been well documented.
"Cigarette smoke has arsenic, cadmium, ammonia, carbon monoxide. It has 4,000 elements and chemicals in it and it's known to be a toxic soup," says Dr. Michael Shannon, member of the American Academy of Pediatrics Committee on Environmental Health and director of the Pediatric Environmental Health Center at Children's Hospital in Boston.
Children born to mothers who smoked during pregnancy have higher rates of respiratory illness, including asthma, and ear infections. And some evidence links secondhand smoke exposure in childhood and adolescence to developing cancer in adulthood.
"The problem with tobacco smoke is that [with all of those] chemicals in there, we're not really sure which one is the one" causing the problems, says Yolton.
While the culpable components remain elusive, experts say that as more and more research supports a link between smoking and ill health, parents should do all they can to minimize their child's exposure.
"The message we'd like to give is if you're pregnant, and even after your child is born, you shouldn't smoke and you shouldn't permit yourself to be around smoke" during pregnancy, says Shannon.