A Group 1 carcinogen: cancer of the urinary bladder; In a study published in 1954, workers manufacturing magenta had a 23-fold excess of bladder tumors. [Reference #1] "These evaluations were typically produced at a time when the available data provided a clear indication of increased cancer risk in an occupational group, but not enough information to identify a causal agent. While such broadly defined carcinogenic agents can lead to general industrial hygiene interventions, provide support to compensate exposed workers and stimulate research to identify specific causes, they have limited utility for informing specific prevention activities and may be affected by changes in process, materials and exposure levels over time." [
PMID 29769352] See "Magenta" and "CI Basic Red 9."