Reference summary — not medical advice or a personal risk estimate.
Secondhand smoke
Combustion products from someone else's tobacco use in shared indoor space.
Also known as: passive smoking, environmental tobacco smoke
What this does NOT mean
Finding a factor documented in this product category does not establish that ordinary use of secondhand smoke causes cancer. It means research — through regulatory testing, recall records, or IARC review — has found that chemical present in this category. Whether it matters for you depends on formulation, dose, frequency, and route of exposure.
What has been documented
- Secondhand tobacco smokeIARC Group 1IARC Group 1Exposure from · high confidence
Direct IARC Group 1 classification.
Evidence source: IARC
How to read this page
A factor appearing on this page means it has been documented in this product category — through EPA / FDA testing, IARC monographs, or regulatory recall records. Whether it presents a meaningful personal risk depends on the specific formulation, dose, and how you're exposed. Click any factor to read what science actually says about it, and where.