Secondhand smoke reduces the sensitivity to cough-eliciting respiratory irritants in children, states study.

Children are exposed to more secondhand smoke than nonsmoking adults, with 60 percent of U.S. children aged 3-11 years and 18 million youth aged 12-19 years exposed to tobacco smoke on a regular basis.
Adult smokers are known to have a less sensitive cough reflex relative to non-smokers, meaning that it takes more irritation to elicit a cough in the smokers. The Monell research team conducted the current study to ask if the cough reflex of children and adolescents who are regularly exposed to secondhand smoke is affected in a similar fashion.
In the study, which appears in Tobacco and Nicotine Research, 38 healthy children aged 10-17 years old inhaled increasing concentrations of capsaicin from a nebulizer. Capsaicin is the burning ingredient in chili peppers and a potent chemical stimulus for cough. Seventeen of the youth were regularly exposed to smoke in the home, while 21 were never exposed to smoke at home. Parents also were tested.
The amount of capsaicin in the nebulizer was increased after each inhalation until the subject coughed twice. The capsaicin concentration that induced the two coughs was labeled as the individual''s cough threshold.
Youth regularly exposed to secondhand smoke required twice as much capsaicin to trigger cough as did non-exposed children, meaning that the exposed children were less sensitive to the irritating environmental stimulus. A similar finding was true for the parents, confirming earlier findings.
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"This study suggests that even if an exposed child is not coughing, his or her respiratory health may still be affected by secondhand smoke," said Wise.
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Future research will explore the relationships among secondhand smoke exposure, cough reflex and the sensory response to cigarettes to ask if exposure-related decreased sensitivity to irritants makes smoking more pleasurable to teens. The researchers will also seek funding to determine whether impairment of the cough reflex is reversible and how this may relate to the age when secondhand smoke exposure ceases.
Also contributing to the study was Susana Finkbeiner of Monell. This project was funded by a grant from the Pennsylvania Department of Health, which specifically disclaims responsibility for any analyses, interpretations, or conclusions.
Source-Newswise