VOA标准英语2010年-Have a Smoke at Your Child's Expense（在线收听）

"These kids are at higher risk for the development of plaque in their arteries as time goes by." - Donald LaVan, MD

A new study has found that teenagers who are exposed to second-hand tobacco smoke are more likely to have changes to their blood vessels that could lead to heart disease later in life. 

Researcher Katariina Kallio of the University of Turku in Finland says her study on teenagers extends previous research, which found cardiovascular damage in grown-ups who breathed in other peoples' smoke.

"We know previously that in adults there is that kind of association, but we didn't know that in adolescents," she said in a telephone interview. "So somehow it was a surprise that there is already in adolescents these kinds of changes."

Significant changes

Changes include thicker walls in the youngsters' blood vessels. American Heart Association spokesman Dr. Donald LaVan explains why that change in the arteries is significant.

"The blood vessel wall, when it becomes thickened and the lining is disturbed, is more sensitive to the effects of cholesterol deposition. So therefore, these kids are at higher risk for the development of plaque in their arteries as time goes by."

Plaque inside the artery can restrict blood flow, and makes blood clots more likely. Blood clots can block an artery and cause a heart attack.

In their study, the researchers tested blood for cotinine, a chemical which is produced when nicotine is metabolized, so they got an objective measure of how much smoke the teenagers were exposed to. They also did ultrasound and other tests to measure blood vessel function and the thickness of the artery wall.

Dr. Kallio agrees with Dr. LaVan that the results support the recommendation that kids be kept away from tobacco smoke.

Undoing the damage

"Exposure to tobacco smoke is a risk factor for cardiac disease already in adolescents, and that's why this study supports that children and adolescents need smoke-free environments," said Kallio.

Although there is some evidence that artery damage caused by second-hand smoke in adults may be reversible, LaVan says it's unclear whether that's also true for adolescents.

"We think that they may be. We do know that people who are taken out of high tobacco smoke environments have a definite drop in developing coronary artery disease. There's been studies that show that in adults, that when they're taken away, it is a prevention."

The study was published in the journal "Circulation: Cardiovascular Quality and Outcomes," which is published by the American Heart Association.