According to a study by the Monell Center, sensitivity to cough-eliciting reparatory irritants becomes decreased in healthy kids and adolescents when they are exposed to secondhand smoke. This finding might help explain why kids of smokers have a higher risk of bronchitis, pneumonia and other diseases, as well as why they pick up the habit during adolescent years.

Julie Mennella, Ph.D., a developmental biologist at Monell and co-director of the study, said:

“Cough protects our lungs from potentially damaging environmental threats, such as chemicals and dust. Living with a parent who smokes weakens this reflex, one of the most vital of the human body.”

Nonsmoking adults are actually exposed to less secondhand smoke than children. Estimates show that 60% of kids in the United States aged 3-11 years and 18 million adolescents aged 12-19 are regularly exposed to tobacco smoke.

In order to elicit a cough in adult smokers, it takes more irritation than it would for non-smokers because they have a less sensitive cough reflex. This study, published in Tobacco and Nicotine Research, was conducted to see if children and adolescents experience the same impairments of the cough reflex when exposed to cigarette smoke.

The researchers examined 38 healthy kids (ages 10-17) inhaling increasing concentrations of capsaicin, which is the burning ingredient in chili peppers and a potent chemical stimulus for cough, from a nebulizer. Twenty one of these adolescents were never exposed to tobacco smoke at home, while 17 of the adolescents were exposed to smoke at home on a regular basis. Parents were also analyzed.

After each inhalation, the subject received an increasing amount of capsaicin until he or she coughed twice. The person’s cough threshold was considered the capsaicin concentration that forced him or her to cough twice.

Results showed that those exposed to secondhand smoke on a regular basis required twice as much capsaicin to trigger cough compared to non-exposed children. The finding shows that the exposed kids were not as sensitive to the irritating environmental stimulus. As expected, parents also had similar results.

The research proves there is a serious health risk from exposure to secondhand smoke, that sometimes goes unnoticed. Exposed children develop an impaired cough reflex which makes them less capable of dealing with threats in the environment, and can even lead to an increased risk for developing respiratory illness.

Paul Wise, Ph.D., Monell sensory scientist, said:

“This study suggests that even if an exposed child is not coughing, his or her respiratory health may still be affected by secondhand smoke.”

Authors suggest that an insensitive cough reflex could potentially increase the risk of adolescents to pick up the habit by making experimentation with smoking less unpleasant.

The team hopes to further explore the associations between secondhand smoke exposure, cough reflex and the sensory response to smoke to find out if exposure-related decreased sensitivity to irritants makes smoking more pleasurable to young people. They also want to determine if the impaired cough reflex is reversible and if age of exposure to secondhand smoke is related.

Written by Sarah Glynn