About 60% of women and 10% of men dye their hair, according to the Cosmetic Toiletry and Perfumery Association. But this is not risk-free. It can cost a fortune and there's also the more serious risk of a full-blown allergic reaction (small at three per million) or skin irritation. More worrying are reports of an increase in miscarriage – and a rise in your likelihood of developing bladder cancer or a type of blood cancer if you dye your hair more than nine times a year.
The dilemma: Nothing is without risk – so do you really need to stop dyeing your hair? Semi-permanent dyes wash out after six to 10 washes. The dyes that have been linked to cancer are permanent. They contain chemicals that penetrate the hair shaft and follicles and, in the presence of hydrogen peroxide, change the hair's colour. Most of these dyes contain compounds called aromatic amines, which we absorb a small amount of, and then excrete in our urine.
Before the 1980s some hair dyes contained substances called arylamines that caused tumours in animal studies. Studies in humans have found a link between lymphomas (a type of blood cancer) and dyeing your hair (one, in 2005, found a 26% increase in lymphomas in those dyeing their hair more than 12 times a year – but only in people who started dyeing their hair before the 1980s when more risky chemicals were used, although the authors of the study could not identify which chemicals to avoid). But a study in the Journal of the American Medical Association, also in 2005, which added up the results from 71 studies did not find strong evidence of an increase in bladder cancer or lymphomas – although it found a very small association. Other studies suggest some people, because of certain genes, may be more at risk of developing lymphomas (30 percent more) if they use hair dye – especially darker, heavier dyes. In 2007 the European Commission, which regulates hair dye was twitchy enough to ban 179 chemicals because of concerns that manufacturers could not prove they were safe..
In 2008, the World Health Organisation said there is some evidence that hair dyes increase the risk of bladder cancer for hairdressers who use them all the time. The American Pregnancy Association however, said it was unlikely that hair dye could harm an unborn babyy- too little of the chemicals would reach it- although it did say that pregnant women should avoid strong chemical fumes from ammonia in dye and might want to wait to get their hair dyed until the second trimester.
Solution: There isn't strong evidence of a link between hair dye and cancer, however unhealthy it feels to keep applying smelly chemicals to your hair. However, there is, as shown by the studies, some association. If you are sure you don't want to go grey, you might want to try plant-based hair colour such as henna, make sure you don't leave dye on too long, rinse it off thoroughly and do it less often. Or you could go blonde – it seems lighter dyes have less risk.
