Hair dye use and the risk of developing systemic lupus erythematosus - A cohort study

Objective. To investigate the role of hair dye use in the etiology of systemic lupus erythematosus (SLE). Methods. Participants included 106,391 women enrolled in the Nurses' Health Study, a prospective cohort study. The subjects were ages 30-55 years in 1976, and were free from SLE and any other connective tissue disease at the time of enrollment. In 1976, 1978, 1980, and 1982, subjects were classified as never-users or ever-users of permanent hair dye, based on self-report, Incidence rates of SLE meeting American College of Rheumatology classification criteria were ascertained and confirmed by chart review. Results. Compared with never-users of permanent hair dye, the age-adjusted relative risks (RR) for the development of SLE among ever-users (n = 85 cases) was 0.96 (95% confidence interval [95% CI] 0.63-1.47). Duration of hair dye use was not related to risk of SLE. Women with 15 or more years of use had no increased risk (RR = 0.92, 95% CI 0.46-1.83). There was no relationship between frequency of use or time since first use and risk of SLE, The results were similar when less stringent criteria for SLE were used. Conclusion. We found no evidence that permanent hair dye use, age at first use, frequency of use, or duration of use is associated with the development of SLE.