Smoking in adolescents, saliva cotinine concentrations and respiratory disease

Objective: To assess cotinine levels in the saliva of adolescents and the relationship between these levels, smoking habits and respiratory disease.

Methods: We studied 420 adolescents (54.7% boys and 45.3% girls) aged between 14 and 21 years (mean age, 16.4 +/- 1.32), from state and private schools in Tenerife. An individualized survey, based on the American Thoracic Society's model, was carried out and saliva cotinine concentrations were determined by radioimmunoassay.

Results: Distribution according to smoking habits was as follows: 26.5% were regular smokers, 11% were sporadic smokers, 3.6% were former smokers, 45.6% were passive smokers, and 13.4% were not exposed to smoking. Mean cotinine levels were 225.4 ng/ml in regular smokers, 19.5 ng/ml in sporadic smokers, 17.4 ng/ml in former smokers, 4.2 ng/ml in passive smokers and 2.2 ng/ml in individuals not exposed to tobacco smoke, which demonstrated the correlation between saliva cotinine concentrations and smoking habits (p=0.0001). The cotinine level in smokers of <10 cigarettes/day was 142,7 ng/ml and in smokers of >10 cigarettes/day it was 341,1 ng/ml (p=0.0001). A significant correlation was also found between cotinine concentrations and the number of cigarettes smoked regularly and in the last 24 hours before sample collection (p=0.0001). Lower respiratory tract infection (p=0.0001), chronic cough (p=0.0001) and bronchospasm on physical exercise (p=0.0001) were more frequent in adolescents with higher cotinine concentrations.

Conclusions: Higher saliva cotinine concentrations were correlated with greater tobacco consumption and exposure to tobacco smoke. Adolescents with lower respiratory tract infections, chronic cough and bronchospasm on physical exercise had higher saliva cotinine concentrations.