A prospective study of hair dyes and uterine leiomyomata incidence in the study of environment, lifestyle, and fibroids

OBJECTIVE: To investigate associations between hair dye use and incident uterine leiomyomata (fibroids) among Black participants from the Study of Environment, Lifestyle, and Fibroids.

DESIGN: Prospective cohort study.

SUBJECTS: Reproductive-aged (26-39 years) individuals with an intact uterus residing in the Detroit, Michigan area (n = 868).

EXPOSURE: Self-reported hair dye use (any use vs. no use) in the previous 12 months queried on structured questionnaires.

MAIN OUTCOME MEASURES: Fibroid incidence assessed by transvaginal ultrasounds. We fit Cox proportional hazard models to estimate hazard ratios (HRs) with 95% confidence intervals (CIs), adjusting for age, time in study, educational attainment, annual household income, occupational status, body mass index, age at menarche, parity, use of progestin-only injectable contraceptives within the past 2 years, alcohol consumption, and smoking status.

RESULTS: One hundred and forty nine incident fibroid cases were identified over 3,458 person-years of follow-up. After adjustment for confounders, use of any hair dye product (HR = 1.44; 95% CI = 0.91, 2.26) and rinses that fade (HR = 1.98; 95% CI = 1.04, 3.79) in the previous 12 months was associated with increased fibroid risk, compared with no use, although associations were generally imprecise.

CONCLUSION: In this cohort, use of hair dye products was modestly associated with a higher fibroid risk, which has important public health implications.