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A new study, published in the Journal of the American Medical Association (JAMA) tomorrow, finally ends the long-running debate over use of permanent hair dyes and cancer. The meta-analysis research, which combines data from 79 scientific studies, found no marked increase in cancer risk with personal use of hair dyes.

"Scientific research over the past 30 years linking hair dyes with cancer has been inconclusive," says the study's co-author, Dr. Mahyar Etminan, a researcher at the McGill University Health Centre (MUHC) in Montreal, and the Vancouver Coastal Health Research Institute (VCHRI). "Some studies have claimed that hair dye increases the risk of bladder, breast and hematopoietic cancer, whereas others have shown no risk."

Primary concern has surrounded permanent dyes — rather than so-called temporary or semi-permanent dyes — that contain bleaching chemicals shown to cause cancer in animals. The new research, made possible through CIHR funding to Dr. Etminan, involved an exhaustive review and meta-analysis of existing literature in order to establish the relative cancer risk for those who use these products. The study was conducted in collaboration with Dr. Bahi Takkouche, a professor of preventive medicine at the University of Santiago de Compostela, Spain.

Overall, the study revealed no harmful association between hair dyes and any of the cancers previously associated with their use. "Our discovery will no doubt reassure both users of hair dyes and medical associations, which have been caught between the need to protect the public and avoid widespread panic," notes Dr. Etminan.

"By comparing studies, Drs. Etminan and Takkouche synthesized the results to help us better understand the risks of cancer associated with the use of permanent hair dyes. This synthesis is increasing knowledge, which is needed to improve Canadian and global health," said Dr. Phil Branton, scientific director of the CIHR Institute of Cancer Research. "The results announced today are a perfect example of knowledge translation in action, an important component of CIHR's mandate."

The McGill University Health Centre (MUHC) is a comprehensive academic health institution with an international reputation for excellence in clinical programs, research and teaching. The MUHC is a merger of five teaching hospitals affiliated with the Faculty of Medicine at McGill University — the Montreal Children's, Montreal General, Royal Victoria, and Montreal Neurological Hospitals, as well as the Montreal Chest Institute. Building on the tradition of medical leadership of the founding hospitals, the goal of the MUHC is to provide patient care based on the most advanced knowledge in the health care field, and to contribute to the development of new knowledge.

The Vancouver Coastal Health Research Institute (VCHRI) is the research body of the Vancouver Coastal Health Authority, which includes BC's largest academic and teaching health sciences centres: VGH, UBC Hospital, and GF Strong Rehabilitation Centre. In academic partnership with the University of British Columbia, VCHRI brings innovation and discovery to patient care, advancing healthier lives in healthy communities across British Columbia, Canada and beyond.

The Canadian Institutes of Health Research is the government of Canada's agency for health research. Its objective is to excel, according to internationally accepted standards of scientific excellence, in the creation of new knowledge and its translation into improved health for Canadians, more effective health services and products, and a strengthened Canadian health care system. Composed of 13 institutes, CIHR provides leadership and support to close to 10,000 researchers and research teams in every province of Canada.