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.
Inspect source passages
How strong is the evidence that secondhand smoke harms health?
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
410 publications included after reviewing 7,109 unique records.
410 publications reporting relative risks (RRs) associated with SHS
Conservative SHS risk floors ~8%/5%/1%/1% for IHD/stroke/T2D/lung cancer.
SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively
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
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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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