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We are pleased to announce that the results of the recent IARC Monographs evaluation of the carcinogenicity of three pesticides – the herbicides atrazine, alachlor, and the fungicide vinclozolin – have now been published in The Lancet Oncology. The summary article presents the conclusions of IARC Monographs Meeting 140.
Atrazine was previously evaluated by the IARC Monographs programme in 1998 in Volume 73. Alachlor and vinclozolin were evaluated for the first time.
The herbicides atrazine and alachlor have been widely used globally for weed control in turf and lawns and crops such as corn. Vinclozolin is a fungicide used in agriculture, mainly on fruit and vegetables.
The Working Group evaluated both atrazine and alachlor as probably carcinogenic to humans (Group 2A) on the basis of the combinations of (i) limited evidence for cancer in humans and sufficient evidence for cancer in experimental animals; and (ii) limited evidence for cancer in humans and strong mechanistic evidence in experimental systems. For atrazine, positive associations have been observed for non-Hodgkin lymphoma that is positive for the chromosomal translocation t(14;18). Positive associations have been observed between alachlor and cancer of the larynx.
Vinclozolin was classified as possibly carcinogenic to humans (Group 2B) on the basis of sufficient evidence for cancer in experimental animals and strong mechanistic evidence in experimental systems. The evidence regarding cancer in humans was inadequate.
The full scientific assessment will be published as Volume 140 of the IARC Monographs.
Cattley RC, De Roos AJ, Mandrioli D, Pearce N, Pronk A, Soshilov A, et al. Carcinogenicity of atrazine, alachlor, and vinclozolin Lancet Oncol, Published online 21 November 2025; https://doi.org/10.1016/S1470-2045(25)00702-8
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