public-health
How strong is the evidence that secondhand smoke harms health?
Open access · cc by · source: Europe PMC
Across 410 studies, SHS linked to all nine outcomes; conservative floors were ~8% higher IHD, 5% stroke, and 1% each for T2D and lung cancer (two-star evidence).
Study at a glance
- Design
- Meta-analysis / systematic review — Burden of Proof Risk Function systematic review/meta-analysis of SHS vs nine outcomes
- N
- N=410 · 410 publications with SHS relative risks after screening 7,109+ records
- Population
- Observational studies of secondhand smoke exposure and selected diseases
- Outcome
- Conservative risk increases and star-rated evidence strength for nine outcomes
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
All nine outcomes associated with SHS. Conservatively, SHS raises IHD ≥~8%, stroke ≥~5%, type 2 diabetes ≥~1%, lung cancer ≥~1% (two stars). Otitis media, asthma, lower respiratory infections, breast cancer, and COPD had weaker one-star evidence. Pooled RR examples include IHD 1.26 and stroke 1.16.
Methodology
Systematically reviewed literature to July 2022 (7,109 unique records plus citation mining), retained 410 publications with SHS relative risks, pooled associations with Burden of Proof Risk Function methods, and star-rated evidence strength.
Limitations
Weak star ratings mean residual confounding/bias remain plausible; dichotomous SHS exposure simplifies real intensity/duration.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Even low-intensity maternal smoking raises preterm-birth odds; quitting before pregnancy looks like never-smoking risk.
US birth-certificate analyses showed first-trimester smoking of 1–2 to ≥20 cigarettes/day associated with ORs ~1.31–1.53 for preterm birth; low-intensity smoking in either trimester still increased risk, while quitting before pregnancy tracked with never-smoker risk.
Scope note — SHS Burden of Proof is environmental exposure in non-smokers — not maternal active-smoking dose on birth certificates
Limits the claim's scope: a different population, assay, or outcome.
Conservative Burden of Proof methods still link SHS to multiple adult/child outcomes.
A Burden of Proof synthesis associated SHS with nine outcomes; conservative floors included ≥~8% higher IHD, ≥~5% stroke, and smaller but positive floors for type 2 diabetes and lung cancer (two-star ratings), with additional child respiratory and other endpoints.
Evidence for the claim as stated.
Maternal cigarette dose and preterm birth odds vs Conservative SHS relative-risk floors across outcomes vs Active smoking across CVD subtypes
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Maternal cigarette dose and preterm birth odds vs Conservative SHS relative-risk floors across outcomes vs Active smoking across CVD subtypes
Related papers in this topic
Same topic cluster — not a recommendation engine.