A new study has found that childhood and adulthood exposure to second-hand tobacco smoke increases the risk of death in adulthood.[i]
Second-hand smoke, or environmental tobacco smoke, is a mixture of exhaled tobacco smoke and smoke from the burning tip of a cigarette.
Many studies have previously observed the health effects of childhood exposure to second-hand smoke in children and the health effects of adulthood exposure to second-hand smoke in adults. However, few studies have previously examined the health effects of childhood exposure to second-hand smoke in adults.
Previous research has found that children whose parents smoke at home are at increased risk of chronic respiratory symptoms, asthma and impaired lung function. There is also evidence to suggest that exposure to second-hand smoke as an adult increases the risk of lung and vascular disease.
In the latest study, researchers investigated whether childhood exposure to second-hand smoke causes lung / cardiovascular damage and increases the risk of fatalities in adults.
70,900 non-smokers (never smoked) were selected from the American Cancer Society’s Cancer Prevention Study-II Nutrition cohort. The participants were followed over a 22 year time period.
Information was collected in respect of childhood and adulthood exposure to second-hand smoke. The researchers were interested in all causes of death in adulthood, such as ischemic heart disease, stroke and chronic obstructive pulmonary disease (COPD).
Approximately 25% of study participants lived with a smoker at some point in their childhood, and of those children, 74% lived with a smoker throughout their childhood.
No statistically significant associations were found between childhood second-hand smoke exposure and death from all causes, ischemic heart disease and stroke, although increased hazard ratios were identified in those who lived with two or more smokers throughout their childhood.
However, the researchers observed a statistically significant relationship between those who lived with smokers throughout childhood and COPD.
COPD is caused by a range of other occupational exposures, such as diesel fumes, chemical substances and dusts. Miners and agricultural workers are known to be at increased risk.[ii]
Participants had a 31% increased risk of COPD-related death. This corresponds to about 7 additional deaths per year per 100,000 people who never smoked.[iii] There was also a 21% increase in risk of death from COPD among those who had any level of exposure to second-hand smoke during childhood, but this was not statistically significant.
In respect of second-hand smoke exposure in adulthood, at least 10 hours per week was associated with increased risk of death from all causes, ischemic heart disease, stroke and COPD.
The researchers concluded that the results of the study show that both childhood and adulthood exposure to second-hand smoke increases the risk of death from COPD in adulthood.
[i] Diver, W. R., Jacobs, E. J. & Gapstur, S. M. Secondhand Smoke Exposure in Childhood and Adulthood in Relation to Adult Mortality Among Never Smokers. American Journal of Preventive Medicine 55, 345–352 (2018). https://www.ajpmonline.org/article/S0749-3797(18)31876-2/fulltext (Accessed 22 August 2018)
[iii] Childhood exposure to secondhand smoke may increase risk of adult lung disease death. Science Daily. 16 August 2018 https://www.sciencedaily.com/releases/2018/08/180816081452.htm (Accessed 22 August 2018)