Neurodevelopment in offspring of hairdressers.

The hypothesis that intrauterine exposure to hairdressers' chemicals adversely affects neurodevelopment of the offspring was investigated. Neurodevelopmental characteristics were analysed using a historical cohort study of reproductive disorders among hairdressers in The Netherlands. Because exposure in hair salons to agents toxic to reproductive processes might have changed over time, two specific study periods were examined: from 1986 to 1988 and from 1991 to 1993. Nine thousand hairdressers and 9000 clothing sales clerks (referent group) who were in the reproductive age in the defined study periods were selected by the trade association for service jobs. Frequency matching assured comparability with regard to age. All women were invited by mail to complete a short self-administered questionnaire on their reproductive history, including questions on the ages of their child at the times of the first words, first sentences, and first steps, and the occurrence of seizures during fever. The results showed that in 1986 to 1988 more children of hairdressers started speaking their first words after 15 months and their first sentences after 24 months. For 1991 to 1993 no increased risks of these outcomes were found. Seizures during fever had occurred more often among children of hairdressers in 1986 to 1988, and in 1991 to 1993, especially when women had been working until maternity leave. Although the quality of the data in this explorative study requires careful interpretation, the consistent results seem to indicate adverse effects on neurodevelopment among offspring of hairdressers in the earlier years (1986 to 1988). In the later years the effect seemed to be disappearing. However, these findings should be confirmed in more detailed studies.