Carcinogenicity of gentian violet, leucogentian violet, malachite green, leucomalachite green, and CI Direct Blue 218

Because of their antibacterial and antifungal properties, gentian violet and malachite green have had various medical, veterinary, and aquaculture applications, including the treatment of livestock, animal feed, ornamental fish, and farmed fish and shellfish. In B6C3F1 mice exposed via the diet, gentian violet caused hepatocellular carcinoma in males and females, and histiocytic sarcoma of the bladder, ovary, uterus, and vagina in females.3 In F344 rats exposed in utero, followed by lactational and then dietary exposure, gentian violet caused follicular cell adenocarcinoma of the thyroid gland in males and females, and mononuclear cell leukaemia in females.4 In orally dosed rats, malachite green is excreted primarily in the faeces. After dietary exposure, leucomalachite green caused follicular cell adenoma or carcinoma (combined) of the thyroid gland in male F344 rats, adenoma or carcinoma (combined) of the mammary gland in female F344 rats, and hepatocellular adenoma or carcinoma (combined) in female B6C3F1 mice.5,6 CI Direct Blue 218 is a copper-chelated dimethoxybenzidine-based azo dye used for cellulose, acetate, nylon, silk, wool, tissue, fine papers, and textile goods.