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