According to the World Health Organisation (WHO), hair dyes and other chemicals place hairdressers at an increased risk for cancer.
WHO's International Agency for Research on Cancer (IARC) based in Lyon, France, says being a hairdresser or barber exposes people to materials and chemicals which are likely to be carcinogenic.
In study which conducted a review of six large investigations into cancer risk the IARC researchers found that for male hairdressers and barbers, the risk of cancer of the bladder was between 20 and 60 percent higher than the general population.
They say the risk though "small is consistent" and is less visible among women.
The researchers found among both male and female hairdressers, a heightened risk of 30 percent for lung cancer was seen in some research; they say this could be partly explained by a higher incidence of smoking among hairdressers.
The researchers looked at eight hair dyes and only one could be classified as possibly carcinogenic to humans and also at aromatic amines.
Amines are a large group of organic compounds which containing nitrogen and are thought to be derived from ammonia and are used in the manufacture of plastic, dyes, drugs and pesticides.
Many are considered toxic if ingested, inhaled or reach the skin.
Of the four aromatic amines researched for the study three were classified as probably carcinogenic to humans, while one could not be classified.
For women hairdressers some research suggested an increased risk for ovarian cancer and of non-Hodgkin's lymphoma, but this was not backed up by other research.