All risk factors
Every entry cites at least one primary source. Group 3 (not classifiable) and Group 4 (probably not carcinogenic) are hidden by default — toggle them in if you want the full IARC list.
- IARC Group 1BenzeneAir & Environment
Breathed. Gasoline vapours at the pump, vehicle exhaust, cigarette smoke, and occupational exposure in petrochemicals.
- IARC Group 1Diesel engine exhaustAir & Environment
Breathed. Roadside air, fuelling stations, and occupational exposure in mining, transport, and mechanic work.
- IARC Group 1FormaldehydeAir & Environment
Breathed. Off-gassing from particleboard, plywood, and other pressed-wood products; embalming fluids; some hair-smoothing salon treatments; certain manufacturing.
- IARC Group 1Outdoor air pollutionAir & Environment
Breathed. Air pollution from traffic, industry, and burning of solid fuels. Everyone outdoors breathes some — the level depends on where you live.
- IARC Group 1RadonAir & Environment
Breathed. Naturally occurring radioactive gas that seeps up from soil and rock and can accumulate in basements and ground-floor rooms. Home test kits are inexpensive and mitigation works.
- IARC Group 1Secondhand tobacco smokeAir & Environment
Breathed. Breathing other people's tobacco smoke indoors — in homes, vehicles, and workplaces without smoke-free policies.
- IARC Group 1Dioxin (2,3,7,8-TCDD)Air & Environment
Eaten. Bioaccumulates in animal fat, so dietary exposure (meat, dairy, fish) dominates. Historical industrial accidents produced very high exposures in some communities.
- IARC Group 2AIndoor biomass fuel smoke (wood)Air & Environment
Breathed. Cooking or heating with wood, charcoal, dung, or crop residues — especially on open fires or unvented stoves. Roughly a third of the world cooks this way.
- IARC Group 1Indoor emissions from coal combustionAir & Environment
Breathed. Burning coal indoors for cooking or heating, especially in unvented stoves. Mainly a concern in regions where this is common practice.
- IARC Group 1Polychlorinated biphenyls (PCBs)Air & Environment
Eaten. Contaminated fish from affected waterways. PCBs were banned decades ago but persist in older transformers, sealants, and sediments.
- IARC Group 1Fluoro-edenite fibrous amphiboleAir & Environment
Breathed. Occupational exposure to airborne fibres — historical insulation, building products, or industrial materials.
- IARC Group 2B1,3-DinitropyreneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2B1,6-DinitropyreneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2B2-NitrofluoreneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2B3,7-DinitrofluorantheneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2B3,9-DinitrofluorantheneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2B4-NitropyreneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2B5-MethylchryseneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2B5-NitroacenaphtheneAir & Environment
Listed by IARC mainly as an industrial or research chemical. Where people are exposed has not been written up here; see the IARC Monograph.
- IARC Group 2BBenz[a]anthraceneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2BBenzo[b]fluorantheneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2BBenzo[j]fluorantheneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2BBenzo[k]fluorantheneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2BBenzofuranAir & Environment
Listed by IARC mainly as an industrial or research chemical. Where people are exposed has not been written up here; see the IARC Monograph.
- IARC Group 2BChryseneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2BDibenzo[a,h]pyreneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2BDibenzo[a,i]pyreneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2BEngine exhaust, gasolineAir & Environment
Listed by IARC mainly as an industrial or research chemical. Where people are exposed has not been written up here; see the IARC Monograph.
- IARC Group 2BIndeno[1,2,3-cd]pyreneAir & Environment
Breathed and eaten. Combustion byproduct found in vehicle exhaust, cigarette smoke, smoke from burning wood, and grilled or charred food.
- IARC Group 2BNaphthaleneAir & Environment
Listed by IARC mainly as an industrial or research chemical. Where people are exposed has not been written up here; see the IARC Monograph.
- IARC Group 2Bpara-DichlorobenzeneAir & Environment
Listed by IARC mainly as an industrial or research chemical. Where people are exposed has not been written up here; see the IARC Monograph.