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Secondhand Smoke: Impairing Children’s Cough Reflex?

Guests: Dr. Judy Mennella, Ph.D. & Dr. Paul Wise, Ph.D.;
Host: Christopher Springmann
TRT: 9:45

Christopher Springmann:  I’m Christopher Springmann and this is Body Language.  Coughing–it’s an annoyance, yes, but cough is also a vital protective reflex that helps clear potential toxins from the body.  So do you remember when you or a friend tried a cigarette for the first time with that nasty smoke being pulled into the lungs.  Now, typically, the body reacted violently with coughing which may have convinced you or your friend, we hope, to not do that again.  Now, based on that reaction, what if the cough reflex was seriously desensitized?  Might that increase the risk of adolescents acquiring a smoking habit by making their experimentation with smoking actually less unpleasant and therefore easier?  That’s the question I posed for our next guests.  They are Dr. Judy Mennella, Ph.D., a developmental biologist, and her colleague, sensory scientist, Dr. Paul Wise, Ph.D.  They co-authored a study entitled, “Secondhand Smoke Impairs Vital Cough Reflex in Kids” for the Monell Chemical Senses Center in Philadelphia.  For both of you, welcome to Body Language.

Judy Mennella:  Thank you.

Paul Wise:  Thank you.

CS:    Dr. Mennella, what inspired your work with Dr. Wise on this frankly disturbing and very timely subject?

JM:    Well, for the past few decades, my research has focused on trying to understand how children learn about cigarette smoking from their parents and I’ve focused on how they learn about the odor of tobacco.  What I found is that with experience, children come to learn to like the odor of their parents’ smoke.  Because Monell is such a multi-disciplinary place, I knew that my colleague down the hall, Paul Wise, was studying the cough reflex in adults.  And we both got the idea together to determine whether this really important reflex, which we know is impaired in smokers, is also impaired in the children who live with them.  I should add that this reflex is probably one of the most protective reflexes of the body.  It serves to clear secretions and debris from the throat, which is our portal to the airways.  So we wanted to see if this cough reflex was impaired in children who live with smokers and if this could be, as your introduction stated, one of the mechanisms why children who are exposed to secondhand smoke have so many health impairments and increased risk for asthma, ear infections and the like.

CS:    Now, Dr. Wise, speaking of infections, the findings may also help to explain why children of smokers are more likely to develop pneumonia, bronchitis, COPD, Chronic Obstructive Pulmonary Disease and other diseases and are more likely to experiment with smoking during adolescence.  So, does the desensitization of the cough reflex or the disabling, as the case may be, actually encourage people to become smokers because there’s less bodily resistance?  Is that—is that correct?

PW:    That’s our working hypothesis.  We don’t have hard data to support the position yet, but we can cite a 2010 paper published in the Journal, “Addiction” by Chris Richardson and colleagues there at the University of British Columbia.  So in that study, kids who experience negative sensations like coughing, feeling sick or feeling nervous when they have their first cigarette were about half as likely as those who did not to become habitual smokers.  About 62 percent of their sample reported coughing when they first lit up, so the reaction seems pretty common.  The Richardson study doesn’t prove that desensitized cough reflex would make kids more likely to develop a smoking habit, but the data is certainly consistent with that idea.

CS:    You know, I will address this question to both of you.  How did you do your research?  Obviously, you can’t recruit kids to smoke.  That’s obviously not appropriate.  So how did you do your testing?

PW:    Right.  Well, you’re correct about doing true experiments with smoking.  You can’t just assign people to a group because those are—involves ethical considerations.  Rather, we study children and adults that have already been exposed due to choices or existing living conditions.  Regarding cough sensitivity, we don’t actually test people with cigarette smoke, either.  Rather, we use a model irritant, capsaicin.  So capsaicin is the compound that gives hot chili peppers their bite.  It’s also a potent cough trigger, but it’s relatively safe because it doesn’t cause very much contraction to the lower airways.  So we present capsaicin aerosol with a research nebulizer, delivered metered doses starting at very low concentration.  Concentration gradually goes up until we find the minimum concentration or the threshold that triggers coughing.  And less sensitive people require higher concentrations to make them cough.  It’s a fairly common clinical measure of cough sensitivity.

CS:    Dr. Mennella, what are your thoughts about that?

JM:    Well, I just wanted to expand on what my colleague said.  I think it’s important to know what our findings were, and basically we used the same methods in measuring cough thresholds in the children as we did their parents.  And what we found is that just like smokers, the children of smokers had a reduced cough sensitivity.  That means they needed higher levels of this capsaicin to elicit a cough.  So that tells us that the reduced cough sensitivity was chemo-sensory based.   So I think taken together, the research is pointed into the direction that early experiences are making the drug less aversive to children.

CS:    Our guests are Dr. Judy Mennella, a development biologist and her colleague, sensory scientist, Dr. Paul Wise.  They co-authored a study entitled, “Secondhand Smoke Impairs Vital Cough Reflex in Kids” for the Monell Chemical Senses Center at Monell, that’s M-O-N-E-L-L dot org.  This is an auspicious anniversary of a law that was passed in California four years ago, which essentially banned drivers and passengers in automobiles from smoking when there are children present.  What are your thoughts about that law and how it relates to the causes that you’ve found in your work?

JM:    I think it’s a very important law because research has repeatedly shown that infants and children are especially vulnerable to the harmful effects of secondhand smoke.  And in fact, the U.S. Surgeon General reported that children are more heavily exposed to secondhand smoke than are adults, and this exposure remains a major public health concern.  Smoking in a car, just like any other confined space, increased the levels of these toxins and environmental tobacco smoke that children are going to be exposed to.  I think what our research shows is that because their cough reflex is impaired, they’re especially vulnerable to these toxins in the air.  I also think it’s important to remind parents about the dangers of smoking in confined spaces.  Just recently, there was a paper published in “Pediatrics” about how many parents don’t recognize the dangers of exposing their children to these tobacco residue or vapors in confined spaces.  So it’s an important part, I think, of all of us to educate.

CS:    Well, that’s one of the reasons that we’re doing this show, to provide health, literacy and education.  You know, children are often at the mercy of adults who behave badly, unfortunately.  In fact, the group, Action On Smoking And Health, said that “these defenseless kids are strapped into rolling smoke houses–”  That’s pretty strong language.  “—where the smoke pollution level exceeds that of a typical bar.”  Now, I was very startled to read that.  You know, perhaps I shouldn’t have been, but I was surprised.  What are you thoughts about that, Paul?

PW:    Research consistently indicates that secondhand smoke is harmful, particularly for children and confining kids in rolling smoke houses certainly can’t be a good idea.  And as long as officials use the law as an opportunity to educate parents about potential risks to their children, it seems like a wonderful idea.

JM:    And I think it’s also important to just expand upon what Paul’s saying is for the smoker to realize that by smoking they’re impairing their own cough reflex and, therefore, increasing their risk for disease and other health risks.  And so if they’re going to be in that environment and not cough, that’s one of the consequences of smoking.  They themselves may not realize the dangers that they’re imposing on their children, as well as they’re imposing upon themselves.

PW:    Right.

CS:    Well, you’ve essentially validated much of this research and we’ve been discussing the results of a study entitled, “Secondhand Smoke Impairs Vital Cough Reflex in Kids” which was done for the Monell Chemical Senses Center in Philadelphia at  That’s M-O-N-E-L-L dot org.  Our guests have been Dr. Paul Wise and Dr. Julie Mennella.  Thank you so much for joining us today on Body Language.

PW:    Thank you.

JM:    Thank you.