How strong is the evidence that secondhand smoke harms health?
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).
Source
Health effects associated with exposure to secondhand smoke: a Burden of Proof study
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.
What they did
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.
What they found
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.
The limits
What it doesn't show
Weak star ratings mean residual confounding/bias remain plausible; dichotomous SHS exposure simplifies real intensity/duration.
Key terms
- Secondhand smoke (SHS)
- Involuntary exposure to tobacco smoke from others.
- Burden of Proof Risk Function
- Meta-analytic framework quantifying conservative risk and evidence strength.
- Star rating
- Ordinal grade of evidence strength for a risk–outcome pair.
- Relative risk
- Ratio of disease risk in exposed vs unexposed.
- IHD
- Ischemic heart disease.
Flashcards
Research intelligence for this paper
See its role on concept claims, tensions it is part of, placement history, and related discoveries.
Quiz yourself
Conservative SHS increase for IHD was at least about:
Common questions
Outcomes assessed?
Nine health outcomes, all associated with SHS.
Studies included?
410 publications.
Conservative IHD floor?
About 8% increased risk.
Stronger evidence outcomes?
IHD, stroke, T2D, lung cancer (two stars).
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