In 2005 researchers have studied reports on hair dying lasting since 1966 to the present time, in order to discover if artificially coloring of the hair is really harmful for our health. They discovered 14 studies on breast cancer, 10 studies on bladder cancer and 40 on diseases related to blood cells formation, such as leukemia and Hodgkin's disease. All of the consulted studies claimed that the cancer cases had been caused by hair dying.

After further research on this subject the medical experts concluded that hair dye does not represent a risk factor for breast or bladder cancer, but it still may represent a minor factor that leads to multiple myeloma, leukemia and non - Hodgkin's lymphoma.

Even if there is no solid evidence to sustain that artificially dying the hair can cause the above mentioned blood cells related types of cancer, scientists claim that long term use of hair dye - especially dark colors - may slightly increase the risk of getting ill with Hodgkin's disease.

However, the authors of the research pointed out that hair dye that was manufactured until 1980 was highly more harmful than the ones used in present. Tests proved then that it caused cancer in mice and it was laden with all kinds of harmful chemicals. But the producers of hair dye changed almost radically its formula, trying to eliminate or at least avoid the chemicals known to cause cancer in mice.

The most recent research on the hair dying problem was carried out a few months ago and published in the American Journal of Epidemiology on May 26, 2006. It was conducted at the Catalan Institute of Oncology in Barcelona on data gathered from six European countries. The analyzes showed that the risk of suffering from non - Hodgkin's lymphoma increased with 19% in individuals that use hair color from time to time, while those who get their hair dyed on a regular basis - like monthly - the risk of cancer raises to 26%.