Parks J, McLean KE, McCandless L, et al. Assessing secondhand and thirdhand tobacco smoke exposure in Canadian infants using questionnaires, biomarkers, and machine learning. Journal of Exposure Science and Environmental Epidemiology. Ahead of print. 26 June 2021
https://www.nature.com/articles/s41370-021-00350-4
Multivariable linear regression models, chosen through a combination of conceptual and data-driven strategies including random forest regression, assessed the ability of questionnaires to predict variation in urinary cotinine and 3HC concentrations of 2017 3-month-old infants.
Although only 2% of mothers reported smoking prior to and throughout their pregnancy, cotinine and 3HC were detected in 76 and 89% of the infants’ urine (n = 2017). Questionnaire-based models explained 31 and 41% of the variance in cotinine and 3HC levels, respectively. Observed concentrations suggest 0.25 and 0.50 ng/mL as cut-points in cotinine and 3HC to characterize SHS exposure. This cut-point suggests that 23.5% of infants had moderate or regular smoke exposure.
Comment: Questionnaires dramatically under-represented cotinine and 3 HC exposure levels of 3-month-old infants. Maternal self-reports should be supported by biomarker verification of infant second and third-hand smoke exposures.
Stephen Hamann
