According to the report of British scientists, breathing second-hand smoke turns out to increase levels of two warning symptoms for heart disease, fibrinogen and homocysteine.
"The size of these effects was between around one-third and one-half of that seen in relation to active smoking, which seems to be disproportionately huge, however fits with previous research that has demonstrated similar effects in relation to the risk of illness," said lead investigator Andrea Venn, an associate professor at the University of Nottingham’s Division of Epidemiology and Public Health.
The results of the study are published in the February 13 edition of Circulation: Journal of the American Heart Association.
How the research was performed
For this research, Venn and co-author Dr John Britton gathered data concerning 7 599 adult citizens who took part in the third American National Health And Nutrition Examination Survey (NHANES III, 1988-94). None of these people had ever smoked cigarettes.
The partakers of the research had their blood levels of cotinine (an indicator of nicotine) measured. Moreover, they had their levels of fibrinogen, homocysteine and C-reactive protein measured. All of them constitute the makers of heart disease.
The scientists discovered that eighteen percent of the partakers had no detectable levels of cotinine. The rest of them had either low or high levels. Eighteen per cent of participants with low levels of cotinine and 56 per cent of those with high levels claimed that they lived with a smoking partner or were exposed to tobacco smoke in the workplace.
What’s more, the investigators discovered that the low- and high-cotinine groups had considerably higher levels of fibrinogen and homocysteine, in comparison to those who had no detectable levels of cotinine. The elevated levels of fibrinogen and homocysteine were equivalent to nearly thirty to 45 per cent of levels observed in active smokers.
Low exposure can also e harmful
"Moreover, our research demonstrated that these effects were not limited to individuals exposed to high levels of second-hand smoke but were also obvious in our low-exposure group, the majority of whom experienced not living with a smoker and not being exposed in a workplace," Venn said.
According to Venn, the results of the research indicate that second-hand smoke has a considerable effect on vulnerability to cardiovascular disease, even at relatively low levels of exposure. "Second-hand smoke is probable to be a significant avoidable cause of cardiovascular disease in the society, and it is therefore essential that certain measures are taken to minimize the public’s exposure to second-hand smoke," she explained.
One heart specialist believes that this research provides further evidence of the hazards connected with second-hand smoke.
"In contrast to what the tobacco companies will tell you, there is overwhelming evidence that even second-hand smoke can be harmful," said Dr Byron Lee, an associate professor of cardiology at the University of California, San Francisco.
More harm than expected
Some studies indicate that second-hand smoke inhaled by non-smoking individuals leads to more harm than would be expected, Lee claimed. "This article helps us understand the mechanism behind this noticeable effect, by demonstrating us that passive smoke exposure may increase biomarkers of cardiovascular disease to levels seen in everyday smokers," he added.
In another study concerning second-hand smoke, the Flight Attendant Medical Research Institute has awarded an $8.7 million grant to New York-Presbyterian Hospital/Weill Cornell Medical Centre and other hospitals to observe the persistent effects of second-hand smoke among non-smoking fight participants and other workers of service industry.
Until prohibition on in-flight smoking took effect in 1988, flight participants were regularly exposed to second-hand smoke. Currently, 5 000 of these men and women and others are being asked o take part in a series of clinical research concerning the health effects of second-hand smoke on non-smokers.
