Secondhand smoke is associated with some poorer neurodevelopmental outcomes

Ruoling Chen; A. Clifford; Linda Lang; K. Anstey (2013). Is exposure to secondhand smoke associated with cognitive parameters of children and adolescents?—a systematic literature review. Annals of Epidemiology, 23:652-661.

Systematic review · childhood and adolescence

Twelve of fifteen studies reported inverse relationships between secondhand-smoke exposure and cognitive or developmental outcomes; the evidence remained observational.

Bearing on this claim: Systematic review directly supports an association with cognitive and developmental outcomes, not individual causation.

Xiaoxuan Ou; Xin Wang; Xiao-Ling Zhan; Shuli Shen; Shamshad Karatela; Jin Jing; Li Cai; Ru-Qing Liu; Li-Zi Lin; Guang-Hui Dong (2023). The associations of secondhand smoke exposure with neurodevelopmental disorders and critical time window identification: A systematic review and meta-analysis. Science of the Total Environment, 169649.

Meta-analysis · prenatal and childhood exposure

Secondhand-smoke exposure was associated with ADHD and learning disabilities, but heterogeneity and inconsistent evidence-quality ratings left the overall evidence and critical exposure windows inconclusive.

Bearing on this claim: Meta-analysis supports ADHD and learning-disability associations while rating the overall evidence and critical windows as inconclusive.

Anyan Huang; Kusheng Wu; Zemin Cai; Yuhang Lin; Xuanzhi Zhang; Yanhong Huang (2020). Association between postnatal second-hand smoke exposure and ADHD in children: a systematic review and meta-analysis. Environmental Science and Pollution Research, 28:1370-1380.

Meta-analysis · childhood

Postnatal exposure was associated with ADHD and slightly with conduct problems; the biomarker-defined estimate was smaller, and the authors called for more prospective studies.

Bearing on this claim: Postnatal meta-analysis supports ADHD and slight conduct-problem associations while showing smaller biomarker estimates and calling for prospective confirmation.

K. Yolton; K. Dietrich; P. Auinger; B. Lanphear; R. Hornung (2004). Exposure to Environmental Tobacco Smoke and Cognitive Abilities among U.S. Children and Adolescents. Environmental Health Perspectives, 113:98-103.

Observational · N = 4,399 · ages 6 through 16

After socioeconomic and lead adjustment, serum cotinine was inversely associated with reading, mathematics, and block-design scores but not digit span.

Bearing on this claim: National biomarker study supports inverse reading, mathematics, and block-design associations but not digit span.

V. Rauh; R. Whyatt; R. Garfinkel; Howard Andrews; Lori A. Hoepner; Andria Reyes; Diurka Diaz; D. Camann; F. Perera (2004). Developmental effects of exposure to environmental tobacco smoke and material hardship among inner-city children. Neurotoxicology and Teratology, 26:373-385.

Longitudinal · prenatal exposure through age 2

Prenatal residential secondhand smoke was associated with cognitive delay, especially with material hardship; postnatal exposure did not independently add risk beyond prenatal exposure.

Bearing on this claim: Longitudinal cohort supports prenatal environmental-smoke risk modified by material hardship while finding no independent added postnatal-delay risk.

K. Polanska; A. Krol; D. Merecz-Kot; D. Ligocka; K. Mikolajewska; F. Mirabella; F. Chiarotti; G. Calamandrei; W. Hanke (2017). Environmental Tobacco Smoke Exposure during Pregnancy and Child Neurodevelopment. International Journal of Environmental Research and Public Health, 14.

Longitudinal · N = 461 · pregnancy through age 2

Prenatal environmental tobacco smoke was associated with lower language, cognition, and some motor scores, with timing and statistical precision varying by domain.

Bearing on this claim: Biomarker-informed pregnancy cohort supports selected early language, cognition, and motor associations with timing-dependent precision.

B. Fuemmeler; Trevin E. Glasgow; Julia C. Schechter; Rachel L. Maguire; Yaou Sheng; Tatyana Bidopia; D. J. Barsell; A. Ksinan; J. Zhang; Yan Lin; C. Hoyo; S. Murphy; J. Qin; Xiang-li Wang; Scott H. Kollins (2022). Prenatal and Childhood Smoke Exposure Associations with Cognition, Language, and Attention-Deficit/Hyperactivity Disorder. Journal of Pediatrics, 256:77-84.e1.

Longitudinal · N = 386 · ages 3 through 13

Childhood cotinine was associated with several cognitive, language, memory, flexibility, and attention measures, but the adjusted attention-problem association and prenatal main effects were null.

Bearing on this claim: Childhood cotinine study supports selected cognition, language, memory, flexibility, and attention associations while preserving adjusted null findings.

Karin Oh; Yingying Xu; B. Terrizzi; B. Lanphear; Aimin Chen; A. Kalkbrenner; K. Yolton (2020). Association Between Early Low-Level Tobacco Smoke Exposure on Executive Function at Age 8 Years. Journal of Pediatrics, 221:174-180.e1.

Longitudinal · N = 239 · pregnancy through age 8

Prenatal and childhood cotinine were associated with some executive-function domains, especially task initiation and metacognition, but not with general behavior problems.

Bearing on this claim: Repeated-cotinine birth cohort supports selected executive-function associations while finding no general behavior association.

Amna Zar; Shahad A. Al-Amri; Abdelrahman A. Karen; Albara S. Elkhalaf; Almaha M. Almalki; Aysha M. Abdulrahman; Mashael H. Al-Framarzi; G. Babu; A. Tartour (2025). Association of prenatal tobacco exposure and child neurodevelopment: Analysis of the ECHO cohort study. Tobacco Induced Diseases, 23.

Longitudinal · N = 1,970 · prenatal exposure with outcomes at ages 1 through 42 months

Active maternal smoking predicted cognitive and language delay, but adjusted prenatal secondhand-smoke models did not predict cognitive, language, or motor delay.

Bearing on this claim: Qualifying ECHO-wide analysis supports the scoped outcome-specific proposition by finding active maternal-smoking associations but no adjusted secondhand-smoke association with cognitive, language, or motor delay.

Yu Ni; Logan C. Dearborn; A. Szpiro; C. Loftus; Qi Zhao; N. Bush; K. LeWinn; M. Hazlehurst; Thomas F. Northrup; P. Quintana; E. Hoh; Georg E. Matt; C. Karr (2026). Urinary Cotinine Cut-offs for Tobacco Smoke Exposure in Pregnancy and Associations with Child Intelligence Quotient: A Multi-Cohort Analysis. International Journal of Hygiene and Environmental Health, 272:114744.

Longitudinal · N = 1,593 · pregnancy through ages 4 to 6

Prenatal environmental tobacco smoke was associated with an estimated one-point lower IQ, mainly driven by secondhand exposure, but the adjusted association was not statistically significant.

Bearing on this claim: Qualifying multi-cohort biomarker study estimated lower IQ with prenatal environmental smoke, mainly secondhand exposure, but the adjusted association was not statistically significant.