Exposure of hairdressers to ortho- and meta-toluidine in hair dyes

Abstract

BackgroundCarcinogenic 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.ObjectivesTo clarify exposure of hairdressers to potentially carcinogenic aromatic amines, including o-toluidine.MethodsWe 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.ResultsGenerally, 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.ConclusionsHairdressers 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.

Hepatocellular carcinoma and the risk of occupational exposure

“…Its carcinogenic power is probably due to the ability to determine the formation of DNA adducts, causing damage to the DNA structure. Therefore, O-toluidine is classified in group A [220][221][222][223][224][225][226][227][228][229] .…”

Non-infective occupational risk factors for hepatocellular carcinoma: A review

“…Laboratory and medical staff may be exposed when using it for staining tissues (295,296). Other possible exposure may result from the use of certain hair dyes, the local anesthetic prilocaine and tobacco smoke (297,298). …”

Alterations of telomere length and DNA methylation in hairdressers: A cross‐sectional study

“…Aromatic amines are commonly used in hair dye formulations, although classified carcinogenic aromatic amines have been excluded [Bolt and Golka, 2007]. In a previous study on Swedish hairdressers we found evidence of exposure to aromatic amines, including the human bladder carcinogen orthotoluidine, based on measurements of hemoglobin adducts [Johansson et al, 2015]. Studies have shown that hair dye product on the market today can induce chromosome damage, such as micronuclei or strand breaks [Cavallo et al, 2005;Espinoza et al, 2008].…”

“…The study population was described in detail previously [Johansson et al, 2015]. We recruited 295 hairdressers who had worked as a hairdresser for at least 6 months and 92 non-hairdressers, which included 60 controls who had never used any hair dye in the last 12 months and 32 consumers who had used hair dye on a regular base (about every 8 weeks).…”