What is IARC Group 2A?
Group 2A — probably carcinogenic. 24 factors in the Meyron reference are currently classified this way.
Plain-language explanation
Likely to cause cancer. Evidence in humans is limited, but strong in animals or other studies.
Examples
Glyphosate
On skin and breathed. The active ingredient in many commercial and consumer weedkillers. Highest exposure is agricultural; home gardeners and landscapers also use it.
Night shift work
Lifestyle. Regular work shifts during the biological night that disrupt circadian rhythms — common in healthcare, transport, security, and manufacturing.
Red meat
Eaten. Unprocessed beef, pork, lamb, and similar mammalian muscle meat.
Very hot beverages (above 65 °C)
Drunk. Tea, coffee, soup, mate, or other beverages consumed above 65 °C (149 °F). The temperature is what matters, not the drink — letting it cool reduces this exposure.
Acrylamide
Eaten. Forms during high-temperature cooking of starchy foods — fried potatoes, crisps, toast, biscuits, and coffee roasting. Reducing browning reduces exposure.
Anabolic-androgenic steroids
Self-administered, usually injected. Non-medical use for muscle building in some athletic and bodybuilding communities.
Indoor biomass fuel smoke (wood)
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.
Tetrachloroethylene (perchloroethylene)
Breathed. Solvent used in dry cleaning. Dry-cleaning workers and people living near dry-cleaning facilities can be exposed.
2-Mercaptobenzothiazole
Listed by IARC mainly as an industrial or research chemical. Where people are exposed has not been written up here; see the IARC Monograph.
4-Chloro-ortho-toluidine
Mostly industrial — used as a dye in textiles, leather, paper, or research. Some are or were used in cosmetics or food colouring; check the specific entry.
Reading IARC classifications carefully
The IARC groups describe the strength of evidence that an agent can cause cancer under some conditions — not the size of the risk to any individual, not the dose required, and not how likely exposure is in everyday life. A Group 1 classification does not mean an exposure is unavoidable or catastrophic; a Group 3 classification does not mean it is safe.