Hair dyes used by millions of women contain chemicals linked to cancer, British scientists have warned. They say that both home hair colouring kits and the dyes used at expensive salons pose a potential risk to health.
Writing in a respected scientific journal, they say chemicals in permanent hair dyes can react with tobacco smoke and other pollutants in the air to form one of the most powerful cancer-causing compounds known to man.
With more than a third of women and one in ten men regularly colouring their hair, the researchers say it is ‘imperative’ that the risk to health is quantified.
The warning comes from scientists at Leeds-based company Green Chemicals who conducted a review of the chemistry surrounding hair dye. They said that all the information was already available and they simply ‘joined the dots’ to make the link with cancer.
They warn that chemicals called secondary amines, which are either found in all permanent hair dyes or are formed in them, can penetrate the skin and stay on the hair for weeks, months or even years after the dye is applied.
Over time, they could react with tobacco smoke and exhaust fumes, to form highly poisonous chemicals called N-nitrosamines.
Known to cause cancer, these are banned from use in cosmetics.
But the Leeds researchers argue that they can still be generated via a simple chemical reaction.
Hair dye has previously been linked to a range of cancers, including tumours of the breast, bladder, ovaries and brain and leukaemia.
There are also concerns that increasing numbers of people are becoming allergic to their contents, sometimes with fatal results.
The sale of home hair dye kits alone is worth an estimated £321million a year and the figure is expected to rise as the population ages.
In 2010, the European Commission banned 22 hair dyes which put long term users at risk of bladder cancer.