Chapter 04 · People & supply chainsHuman Rights & Social Sustainability
Carcinogen
Definition
Any substance, mixture, exposure circumstance or agent that can cause cancer. The WHO's International Agency for Research on Cancer (IARC) classifies agents through its Monographs programme: Group 1 (carcinogenic to humans, ~135 agents), Group 2A (probably carcinogenic, ~98), Group 2B (possibly carcinogenic, ~329) and Group 3 (not classifiable, ~498), drawing on human epidemiology, animal studies and mechanistic evidence.
References
Group definitions and agent counts; programme scope since 1971.
Four-group system; three evidence streams; hazard vs risk assessment distinction.
Overview
What it means
IARC classification is a *hazard* identification — it says whether an agent can cause cancer under some conditions, not the size of the risk at a given exposure (that is risk assessment, done by regulators). This distinction matters: Group 1 contains both tobacco smoke and processed meat, at vastly different potency.
The Monographs are the scientific backbone for regulatory action — REACH CMR criteria, OSHA and GHS hazard classes, pesticide approvals — and have evaluated over 1,000 agents since 1971.
How it is used
Regulators translate hazard classes into bans, exposure limits and labelling; companies screen substances against carcinogen lists for substitution (e. g. Chemical Footprint Project CoHCs, the SIN List); occupational-health practice sets controls for workplace carcinogens.
Why it matters
Carcinogen classification is where environmental-health science meets commerce: listing decisions drive reformulation, litigation and the precautionary architecture of chemical safety.