JMIR Publications

ABSTRACT

Background:

Cosmetic legislation is ensuring the safety of cosmetics for consumers but not for professional use. All around the world, the hairdressing sector constitutes a major occupational group including about 90% of women continuously exposed to numerous chemical composing the hairdressing products, among them the endocrine disrupting compounds such as resorcinol, parabens, phtalates, UV filters. The thyroid-disrupting chemicals are substances of concern as the incidence of thyroid dysfunction has increased recently worldwide and the long-term consequences at neurodevelopmental level in offspring after in-utero expoure were highlighted. Few biomonitoring studies explored occupational exposure to endocrine disruptors in hairdressers and up to date we found no data about the impact on thyroid hormones system.

Objective:

The present study aimed to assess the occupational exposure to resorcinol in French hairdressers and to analyze the relationship with biological thyroid parameters, taking into account the occupational exposure to other thyroid disruptors (parabens, UV filters).

Methods:

A cross-sectional study is carried out in 300 female hairdressers aged 18-45 years compared to 150 controls, who are recruited by six occupational health services. The hairdressers are followed during a 5-day working week to assess exposure data at individual and salon levels (urinary thyroid disruptors (resorcinol, parabens, benzophenone-3, ethylhexyl methoxycinnamate’s metabolits) at different time points, daily job tasks and use of hair products, salon inventory of hairdressing and other chemical products) and blood thyroid parameters (T3, T4, TSH, thyroglobulin, thyroperoxidase and throglobulin antibodies). Information on sociodempographics and residence, alimentary and tobacco consumption, personal use of care and household products, professional career and medical history was collected by questionnaire.

Results:

The inclusion of study population was planned between 2023 and 2025. Until now, a total of XX subjects (XX hairdressers belonging to XX salons, XX unexposed) were included by XX occupational health services. Since the inclusion rates of hair salons (around 10%) and of hairdressers (around 50%), are below those estimated, the inclusion period will be extended till 2026. Further, new partnership with more occupational health services are under study.

Conclusions:

This study will provide new evidence on the occupational exposure of hairdressers to resorcinol and to other thyroid disruptors. The results represent the first data on occupational exposure to resorcinol in France and the relationship with thyroid hormones in hairdressers, a susceptible population of childbearing age. We proposed a timely research based on a partnership with occupational health professionals and designed following a multidisciplinary approach including biometrology and epidemiology. The collection of exposure data at both hairdressers and salon levels allow in-depth exposure assessment to the thyroid disruptors in workplace. Together with the inventory of hairdressing and other chemical products, these results may strengthen the tools for the chemical risk diagnosis and prevention in hair salons.