The results of the recent IARC Monographs evaluation of the carcinogenicity of gentian violet, leucogentian violet, malachite green, leucomalachite green, and CI Direct Blue 218 have now been published in The Lancet Oncology. This summary article presents the conclusions of IARC Monographs Meeting 129.
All these agents were evaluated by the Working Group for the first time.
Gentian violet, leucogentian violet, malachite green, and leucomalachite green have a wide range of uses as dyes and stains, including for textiles, and for biological, medical, forensic, and analytical samples. Gentian violet and malachite green are also antifungal, antiparasitic, and antibacterial agents used in veterinary medicine. Dietary exposure to their leucometabolites may occur through fish consumption if gentian violet or malachite green have been used in aquaculture. CI Direct Blue 218 is used as a dye for cellulose, acetate, paper, textiles, and other materials.
The Working Group evaluated gentian violet, leucomalachite green, and CI Direct Blue 218 as possibly carcinogenic to humans (Group 2B) mainly on the basis of sufficient evidence for cancer in experimental animals. Leucogentian violet and malachite green were each evaluated as not classifiable as to its carcinogenicity to humans (Group 3). For leucogentian violet, evidence regarding cancer in humans, cancer in experimental animals, and carcinogen mechanisms was inadequate because no data were available. For malachite green, there was limited evidence for both cancer in experimental animals and carcinogen mechanisms.
The full scientific assessment will be published as Volume 129 of the IARC Monographs.
IARC Monographs Volume 129 Working Group
Carcinogenicity of gentian violet, leucogentian violet, malachite green, leucomalachite green, and CI Direct Blue 218
Lancet Oncol, Published online 25 March 2021;