What Hairdressers Should Know about Bladder Cancer

hairdressers and bladder cancer

Your favorite hairdresser may be in danger of developing bladder cancer. Research indicates that cancer-causing aromatic amines found in some hair dye products are responsible for bladder cancer, even though some of the toxins—but not all of them--were gradually phased out during the 1970s.

Newest study
At the Division of Occupational and Environmental Medicine in Lund, Sweden, a scientific team evaluated blood samples from 295 female hairdressers, 60 people who had not used hair dyes within the past 12 months, and 32 individuals who regularly used hair dyes.

The researchers analyzed eight different potentially cancer-causing aromatic amines: ortho-toluidine, meta-toluidine, para-toluidine, 2-, 3-, and 4-ethylaniline, and 2,3- and 3,4-dimethylaniline. They found that weekly levels of o-toluidines and m-toluidines among the hairdressers corresponded with how many permanent light hair dye and hair-waving treatments they performed (o-toluidines only in the latter group).

According to the Environmental Protection Agency (EPA), o-toluidine (o = ortho) is highly toxic when people absorb it through their skin, inhale it, or swallow it. This chemical has been classified as a probable human carcinogen by the EPA. Both o-toluidines and m-toluidines have been linked to bladder cancer as well as an elevated risk for leukemia and non-Hodgkin lymphoma.

Short-term exposure to the toxin can cause central nervous system depression. When exposure is longer, symptoms may include skin lesions, weight loss, cyanosis, anorexia, central nervous system depression, and methemoglobinemia. This latter condition is characterized by abnormally high levels of a form of hemoglobin that ultimate can result in a reduced ability of the red blood cells to send oxygen to the tissues.

An important point to remember is that bladder cancer in humans is associated with aromatic amines that can be latent for three to four decades. Thus, some cases of bladder cancer appearing now may be related to chemical exposure from 30 to 40 years ago.


Previous research
Results of a 42-study meta-analysis published in 2010 explored the risk of bladder cancer among hairdressers. All but one of the studies showed a significantly increased risk for this form of cancer among hairdressers.

Not surprisingly, the risk was found to be greater for hairdressers who had worked in the field for at least 10 years. The researchers could not make a definitive ruling on the impact of smoking along with the exposure to carcinogens.

In a 2012 study appearing in Environmental Health, the expert team noted that smoking is a well-known risk factor for bladder cancer, as is exposure to arsenic in drinking water at concentrations exceeding 300 micrograms per liter.

In addition, exposure to aromatic amines (2-naphthylamine, 4-aminobiphenyl, and benzidine) along with 4,4’-methylenebis(2-chloroaniline), found in hair dyes, increase the cancer risk. The National Cancer Institute estimates that nearly 75,000 people will be diagnosed with bladder cancer in 2014, and that more than 15,000 will lose their battle with the disease.

Common symptoms of bladder cancer include blood in the urine, urinary urgency, feeling the need to urinate without results, need to strain when urinating, and pain when urinating. Since these symptoms may be related to urinary tract infections or other health problems, anyone who experiences these issues should consult their healthcare provider.

Bottom line
Although use of several aromatic amines have been restricted, hairdressers who use permanent hair dyes and hair waving products may still be exposed to some of these cancer-causing chemicals. The authors have concluded that such products should be screened to identify sources of exposure and that hairdressers should use protective gloves.

Environmental Protection Agency
Harling M et al. Bladder cancer among hairdressers: a meta-analysis. Occupational and Environmental Medicine 2010 May; 67(5): 351-58
Johansson GM et al. Exposure of hairdressers to ortho- and meta-toluidine in hair dyes. Occupational and Environmental Medicine 2014 June 9 online
Letasiova S et al. Bladder cancer, a review of the environmental risk factors. Environmental Health 2012 Jun 28; 11 Suppl 1:S11