Passive Smoking Hurts Your Heart

A new study on the effects of second-hand smoke on heart disease has found that people exposed to passive smoking may be at a higher risk of heart disease as compared to those who are not exposed. The study is unique as it was the first to measure exposure to second hand smoke through levels of a nicotine by-product in the blood.

Several studies have been conducted till date to assess the relation between cigarette smoking – both active and passive – and heart disease. However all previous studies used participants’ memory about being exposed to smoke for arriving at conclusions.

Working on a different methodology from previous studies, Dr. Andrea Venn from the University of Nottingham and other researchers measured the level of cotinine in the participants’ blood for this new study. Cotinine is an organic by-product of nicotine and by measuring its levels; it is possible to know the level of nicotine intake. Nicotine being highly specific to tobacco smoke, levels of cotinine in blood serum help track exposure to tobacco smoke and its toxic components.

Data gathered during the third National Health and Nutrition Examination Survey of 1988-1994 was examined for the study. The study population included nearly 7,600 adults who had never smoked. Analysis of the data revealed that there were no detectable levels of cotinine in 18% of the participants. The remaining subjects had either low or high levels of the chemical.

Out of these, 18% of subjects with low levels of cotinine and 56% of those with high levels either had a smoking family member at home or were exposed to smoke at work. Significantly higher levels of fibrinogen and homocysteine were also observed by the researchers in subjects with cotinine in the blood as compared to those with none.

The researchers found levels of fibrinogen and homocysteine to be equivalent to 30% to 45% of the levels normally observed in active smokers. This led researchers to the conclusion that even low-level and indirect exposure to cigarette smoke increases the risk of heart disease by a significant amount.

“Even when participants weren’t exposed to smoke at the workplace or at home, many had low or high levels of cotinine in their blood,” Dr. Venn said in the study published in Circulation, a journal of the American Heart Association.

“These people may be exposed in bars or restaurants or perhaps in other people’s homes such as those of relatives or friends. This suggests that even people exposed to low levels of second-hand smoke may be at increased risk,” she said.

“This study supports existing evidence that exposure to second-hand smoke is an important avoidable cause of cardiovascular disease,” the doctor said. “It also highlights the importance of implementing measures to protect the public from second-hand smoke such as banning smoking in enclosed public places and workplaces,” Dr. Venn added.

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