ASPO Abstracts
Hair dye and chemical relaxers in relation to breast cancer risk in a large US population of black and white women
Category: Molecular Epidemiology & Environment
Conference Year: 2019
Abstract Body:
Purpose: Evaluate the relationship between use of hair dye and chemical relaxers and breast cancer risk by race.Methods: Eligible Sister Study participants (N=45,449) ranged in age from 35-74 and had a sister with breast cancer but were breast cancer-free themselves at enrollment (2003-2009). A self-completed questionnaire on use of personal care products included questions on the use of hair dye and other hair products in the past 12 months. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the association between hair treatments and incident breast cancer.Results: Over an average 8.3 years of follow-up, 2,759 breast cancer cases were identified. 55.4% of participants had used permanent dye at least once in the past 12 months. Overall, breast cancer was modestly associated with personal use of permanent hair dyes (HR=1.07, 95% CI 0.99-1.16) as well as with applying semi-permanent dye to another person (HR=1.30, 95% CI 1.07-1.59). A higher risk of breast cancer was also observed for chemical straighteners or relaxers: both personal use (HR=1.21, 95% CI 1.01-1.44) and application to others (HR=1.27, 95% CI 0.99-1.63). Associations were stronger for black women among whom breast cancer risk was elevated for permanent dye use (HR=1.43, 95% CI 1.07-1.89), especially for use of dark dyes (HR=1.52, 95% CI 1.08-2.06).Conclusions: We observed a higher risk of breast cancer associated with both application to another person and personal use of chemical straightener or relaxers and for personal use of hair dye, especially in black women. These results support evidence that endocrine disrupting compounds and known carcinogens found in hair dyes and chemical relaxers, both common exposures, may be relevant to breast carcinogenesis. The stronger associations observed for black women are consistent with toxicological evidence that hair products used predominately by black women may contain more hormonally-active compounds.
Keywords: breast cancer, hair dye, chemical relaxers