If you use home hair care dye products, especially if you're living abroad, you might want to reassess the beauty treatment as a new research report claims some products may contain a carcinogenic element that's banned in Europe.

The report says carcinogens in hairdressers' blood may be connected to how often they dye hair or use a chemical perming agent to curl hair. They are recommending further studies to investigate the issue and suggest the dye and perm product ingredients be analyzed.

The news, reported in the British Medical Journal, says the chemical culprit may be toluidines that are banned in the European Union. The research involved 295 female hairdressers. Scientists measured the level of eight aromatic amines, including toluidines, in the women's blood. Of the group, 32 were regular users of hair dyes and 60 had not used either a hair dye or perming agent in the past 12 months.

"Among the hairdressers, levels of o- and m-toluidines tended to rise in tandem with the number of weekly permanent light hair color treatments they applied. A similar trend was seen for perming treatments in respect of o-toluidine levels," states a press release on the research.

The report notes that in the 1970s nearly 90 percent of commercial hair dye products included carcinogenic substances and that finding led to the eventual ban on such chemicals.

The Division of Occupational and Environmental Medicine at Lund University in Sweden conducted the study. According to the World Health Organization, hairdressing as a profession is likely a carcinogenic occupation that may lead to higher risk for bladder cancer.

"The measured levels of o-toluidine in blood among hairdressers were in general low. However, exposure to o-toluidine should be kept as low as possible since it is a carcinogenic compound," said study researcher Gabriella M. Johansson.

A similar study, done in Turkey, reveals o-toluidine concentrations could be nearly 100 times stronger in dark-yellow permanent hair dye and 500 times stronger in black dyes.

The National Institute for Occupational Safety and Health recommends occupational exposure to toluidine is kept as low as possible.