A study carried out by the Catalan Institute of Oncology in Spain combined data from six European countries, including Ireland, and found a significantly increased risk of lymphoma amongst people who used hair dye.

Those who dyed their hair, even irregularly, were found to be 19% more likely to develop cancer, while frequent users of dye had a 26% risk.

According to Silvia de Sanjose, a Senior Epidemiologist at the Cancer Institute of Oncology in Spain, the results of the study emphasised the need for hair dye companies to remove all carcinogenic substances from their products.

"Harmful components of the dye are getting metabolised through the scalp, and are passed through the bladder, which we believe sometimes results in bladder cancer, " she said. "It is very important to keep a close eye on what is going on in the industry. We need to keep a strict control on the products being used."

The study also found that there was a significantly higher risk of cancer among people who started colouring their hair before 1980, with 37% of this group more likely to develop lymphoma.

"Before 1980, hair-dye products had a lot of carcinogenic products in them, which is why we found a much higher instance of risk in people who were dying their hair in the '60s and '70s, " said de Sanjose. "Fortunately, the industry was forced to remove those substances and make much cleaner dyes, so hair dye is safer now than it was 20 years ago."