Individuals who are consistently exposed to permanent hair dye may be at an increased risk for developing bladder cancer, according to a study recently published in the International Journal of Cancer.
The study was the first to examine the link between exposure to hair dye and the development of bladder cancer. The study focused on individual exposure as well as occupational exposure for salon workers who apply hair dyes for clients.
Researchers at the University of Southern California School of Medicine in Los Angeles analyzed data from 897 patients with bladder cancer and compared it with data from 897 individuals without bladder cancer. The researchers obtained information regarding personal use of permanent hair dye and made adjustments for cigarette smoking, which is the biggest risk factor for bladder cancer.
Even with the smoking adjustment, the researchers found that individuals who used hair dye at least once a month were twice as likely to develop bladder cancer as individuals who did not use hair dye. In addition, individuals who had been using permanent hair dye at least once a month for 15 years were three times as likely to develop bladder cancer than those who refrained from using hair dye. Furthermore, individuals who worked as hairstylists for 10 or more years were five times more likely to develop bladder cancer than individuals who were never exposed to hair dye.
The researchers concluded that the risk of bladder cancer increased as the frequency and duration of exposure to hair dye increased. Although the results indicate an increased risk, they do not yet warrant an overall recommendation to the public regarding hair dye. More research will be necessary to further define any risks posed by permanent hair dye.
In the past, other research has suggested that while frequency and duration of exposure to hair dye may be important, the key factor in hair dye exposure is the specific shade. Apparently, the darker shades of hair dye contain significantly more chemicals than the blonde shades. Previous studies by the National Cancer Institute and the American Cancer Society have failed to establish a link between exposure to hair dye and cancer.
Individuals who are concerned about their use of hair dyes and the possible increased risk of cancer may choose to avoid using hair dyes, use the dyes less frequently, use lighter shades, and/or reduce direct skin contact with the dye. Research will be ongoing to evaluate the link between permanent hair dye and bladder cancer. (International Journal of Cancer, Vol 91, No 3, 2001).