Objective: To evaluate the association between personal hair dye use and risk of multiple myeloma among women.
Methods: We conducted a population-based case-control study to identify 175 cases of multiple myeloma and 679 controls. Cases and controls were interviewed in-person by trained interviewers regarding their use of hair coloring products. Subjects were asked to report the type and color of the hair coloring product used, age at first use, age use stopped, duration, and the frequency of use per year. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated using unconditional logistic regression to compare never users with four exposure groups: all users, ever semi-permanent users, ever permanent users, and dark permanent users (most frequent use).
Results: We did not find any association between ever reporting hair coloring product use and myeloma risk among all users: OR=0.8, 95% CI=0.5-1.1, semi-permanent users: OR=0.7, 95% CI=0.4-1.2, permanent users: OR=0.8, 95% CI=0.5-1.1, or dark permanent users: OR=0.8, 95% CI=0.5-1.3. There were no significant associations among women who used hair dyes before 30 years of age, who started use before 1980, who had ¡Ý240 lifetime applications, or for dark permanent users with 28 or more years of use.
Conclusion: We did not find any evidence of an association between hair coloring product use and myeloma risk. However, given the conflicting body of literature on hair coloring product use and risk of multiple myeloma, this question should be further evaluated in larger studies or consortia, and in high risk groups.