New studies have found that people who dye their hair on a regular basis may have a higher risk of cancer, specifically bladder and breast cancers, according to researchers from the Medical University of Vienna. This conclusion comes from the fact that hair dyes contain certain chemicals that have been held responsible for this association over the past several years, according to the study authors.

This is the largest analysis of the topic to date, which followed 117,200 women from the United States over 36 years, according to the study. A specific analysis of the data from a cohort study of American nurses who had regular hair coloring had no significant effect on most types of cancer, with a few exceptions.

The International Agency for Research on Cancer, a part of the World Health Organization, has classified occupational exposure to hair dyes as a probable human carcinogen, whereas personal use of hair dyes could not be classified. However, as current epidemiological evidence is far from conclusive, there is concern about the carcinogenic potential of personal use of permanent hair dye, especially for those that are particularly aggressive and most commonly used.

The current study found no link between personal use of permanent hair dye and the risk of most cancers or cancer-related mortality. However, the study did find a positive association for the risk of basal cell carcinoma, hormone receptor-negative breast cancer, and ovarian cancer, according to the study authors.

Additionally, the study found evidence for heterogeneity due to natural hair color, an increased risk of Hodgkin lymphoma only in women with naturally dark hair, and a higher risk of basal cell carcinoma observed in women with naturally light hair.

“The present prospective cohort study offers some reassurance against concerns that personal use of permanent hair dyes may be associated with an increased risk of cancer or mortality,” said study author Eva Schernhammer, MD, DrPH, in a press release. “Nevertheless, we also found a positive correlation for the risk of some cancers.”

Schernhammer added that the current findings are limited to white women from the United States and may not extend to other populations.

“Our results justify further prospective validation,” Schernhammer said. “This depends on different populations and countries, different susceptibility genotypes, cancers if different genotypes and molecular genetic phenotypes, different exposure settings (personal use vs occupational exposure), different time points and different colors of the permanent hair dyes used (dark dyed vs light dyed), with refined exposure estimates and should be interpreted in the light of the totality of the evidence.”

REFERENCE
Hair dye and cancer risk: largest study yet. Medical University of Vienna. https://www.meduniwien.ac.at/web/en/about-us/news/detailsite/2020/news-im-september-2020/hair-dye-and-cancer-risk-largest-study-yet/. Published September 3, 2020. Accessed September 3, 2020.