Reproductive disorders among hairdressers.

To evaluate whether hairdressers have an increased risk of reproductive disorders, we conducted a historical cohort study in the Netherlands. Because exposure to reproduction toxic agents in hair salons may have changed over time, we studied two specific periods: conceptions in 1986-1988 and in 1991-1993. We ascertained 9,000 hairdressers and, as a comparison group, 9,000 clothing salesclerks from their respective trade associations. All were of reproductive age in the defined study periods. Frequency matching on 5-year age groups ensured comparability with regard to age. All women were approached by mail to complete a short, self-administered questionnaire on reproductive history, including questions on time-to-pregnancy, spontaneous abortion, livebirths, and congenital malformations. In the analyses, we used random effect models to account for correlated outcomes (multiple pregnancies per woman). The results show that hairdressers who conceived in 1986-1988 had an increased risk of prolonged time-to-pregnancy of more than 12 months [odds ratio (OR) = 1.5; 95% confidence interval (CI) = 0.8-1.6], spontaneous abortion (OR = 1.6; 95% CI = 1.0-2.4), and a low-birthweight infant (OR = 1.5; 95% CI = 0.7-3.1). In both periods, more major malformations occurred among children of hairdressers, but numbers were small. These results indicate an increase in reproductive risks for hairdressers in earlier years that now seems to be disappearing.