Don’t take our word for it. Here’s every fact on this site, with its evidence grade, its caveats, and a link to the source, so you can check us.
We start you on the strong ones: findings that have been replicated or come from one large, well-controlled study. Moderate and weak facts are here too, labeled for what they are. Use “Link to this fact” to share a single card.
Health effects / Review of other studies
In 2019, IARC upgraded styrene from Group 2B to Group 2A ("probably carcinogenic to humans"), based mainly on mechanistic/genotoxicity evidence, with limited human epidemiological evidence linking occupational styrene exposure to lymphohematopoietic cancers (leukemia and lymphoma).
Strong evidence.
Caveats
Classification by an international expert Working Group reviewing all available literature, not a single primary study; "limited evidence" in humans is the IARC term of art, one tier below "sufficient".
Source: IARC 2019 (Vol. 121) Link to this fact
Health effects / Other evidence
IARC's alphabetical list (last update November 2018) printed formaldehyde (Vol 100F, 2012), benzene, ethylene oxide, trichloroethylene and vinyl chloride as Group 1, carcinogenic to humans, as of that date.
Strong evidence: 2018 snapshot; hazard classification only, not a statement of risk at product-use levels; later re-evaluations are not reflected.
Source: IARC 2018, Agents Classified by the IARC Monographs, Vols 1-123 Link to this fact
Health effects / Other evidence
In July 2024 the WHO's cancer agency (IARC) classified talc as 'probably carcinogenic to humans' (Group 2A), the second-highest certainty level, on limited human evidence for ovarian cancer, sufficient animal evidence (rats) and strong mechanistic evidence.
Strong evidence: This is a hazard classification, not a measure of risk at any exposure level; the human evidence is rated only limited.
Source: IARC Press Release 352 (2024) Link to this fact
Health effects / Other evidence
IARC's new talc evaluation covers talc not containing asbestos; talc containing asbestos was left out because it is already part of the definition of asbestos, a Group 1 carcinogen that causes mesothelioma and cancers of the lung, larynx and ovary.
Strong evidence: Asbestos classification dates from 2009; this release restates it.
Source: IARC Press Release 352 (2024) Link to this fact
Information, not medical advice. See also: myths we won’t tell you.