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.
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.