Hairdressers and barbers are at increased risk of developing cancer as a result of their use of hair dyes. These risks could also extend to personal use of the dyes.
A panel of the International Agency for Research on Cancer (IARC) in Lyon, France reviewed the evidence and found a consistent risk of bladder cancer in male hairdressers and barbers. A second review of the evidence on personal hair dye use found some studies suggested a possible association with bladder cancer, lymphoma, and leukemia.
However, the panel found that the evidence was inadequate to classify the carcinogenicity of personal hair dye use.