Trends of cotinine and secondhand smoke exposure rates in children and adolescent aged 6-19 years: Impact of race and socioeconomic factors over two decades.

BACKGROUND

Exposure to smoking or secondhand smoke during childhood and adolescence is linked to various diseases, highlighting the importance of exploring trends in secondhand smoke exposure. Our study examines trends in cotinine (COT) levels and the prevalence of high COT from 1999 to 2020, analyzing the data by gender, age, race, and income level.

METHODS

In this analysis, data from ten National Health and Nutrition Examination Survey (NHANES) cycles, conducted from 1999-2000 to 2017-2020, were utilized. We calculated the mean COT levels and the proportion of secondhand smoke exposure changes, and used linear and quadratic tests to assess the linear and nonlinear trends in these changes.

RESULTS

A total of 23,616 participants aged 6 to 19-year-old were included. COT levels, decreased from 11.47 ng/ml to 6.17 ng/ml. The prevalence of high cotinine in females decreased from 14.02 % to 6.19 %, and in males, it decreased from 15.20 % to 11.04 %.Cotinine levels varied by age group: 16-19 years (from 35.98 ng/ml to 17.24 ng/ml), 13-15 years (from 10.71 ng/ml to 5.85 ng/ml), 10-12 years (from 1.24 ng/ml to 0.27 ng/ml), and 6-9 years (from 0.59 ng/ml to 0.40 ng/ml).The prevalence of high COT in the ≤ 100 % PIR group (from 21.03 % to 12.66 %), 100 %-299 % PIR group (from 13.84 % to 8.31 %), and 300 %-499 % PIR group (from 9.88 % to 8.96 %) all showed a declining trend.

CONCLUSION

The trends in COT levels and the prevalence of high COT showed a declining pattern over time. COT levels and the prevalence of high COT were higher among children and adolescents with lower income levels. Adolescents aged 16 - 19 had significantly higher COT levels and a higher prevalence of high COT compared to other age groups.