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Original article
Exposure of hairdressers to ortho- and meta-toluidine in hair dyes
  1. Gabriella M Johansson1,
  2. Bo A G Jönsson1,
  3. Anna Axmon2,
  4. Christian H Lindh2,
  5. Marie-Louise Lind3,
  6. Mats Gustavsson2,
  7. Karin Broberg2,
  8. Anders Boman3,
  9. Birgitta Meding3,
  10. Carola Lidén3,
  11. Maria Albin1
  1. 1Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden
  2. 2Department of Occupational and Environmental Medicine, University and Regional Laboratories Region Skåne, Lund, Sweden
  3. 3Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
  1. Correspondence to Gabriella Johansson, Division of Occupational and Environmental Medicine, SUS Lund, Lund SE-221 85, Sweden; gabriella.johansson{at}


Background Carcinogenic aromatic amines derived from hair dyes have recently received new attention. One of these is ortho (o)-toluidine, which is classified as carcinogenic to humans.

Objectives To clarify exposure of hairdressers to potentially carcinogenic aromatic amines, including o-toluidine.

Methods We measured eight potentially carcinogenic aromatic amines in the blood of 295 hairdressers, 32 users of hair dyes and 60 controls. The study was restricted to female non-smokers. Lifestyle data were collected for all participants using self-administered questionnaires. Blood samples were taken for analysis of ortho-, meta (m)- and para (p)-toluidine; 2-, 3- and 4-ethylaniline, 2,3- and 3,4-dimethylaniline as haemoglobin adducts. The samples were analysed with gas chromatography–tandem mass spectrometry.

Results Generally, adduct concentrations were in the range of 0–200 pg/g haemoglobin. A comparison of the adduct concentrations found in hairdressers, consumers and controls showed no statistically significant differences. However, for hairdressers, o- and m-toluidine concentrations increased significantly with the weekly number of hair waving (p=0.020) and permanent hair dyeing treatments (p=0.026), respectively. o-Toluidine and m-Toluidine concentrations also tended (p=0.076 and 0.080, respectively) to increase with the frequency of light-colour permanent hair dye treatments.

Conclusions Hairdressers who use light-colour permanent hair dyes, other permanent hair dyes and hair waving treatments seem to be exposed to o- and m-toluidine as indicated by associations with the number of treatments performed. Analyses of hair waving and hair dye products should be performed to identify the possible sources of exposure to o- and m-toluidine.

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