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Background: Outdoor work is associated with high and chronic exposure to solar ultraviolet radiation which might lead to an increased risk of developing skin (pre)malignancies. Prevalence of actinic keratosis (AK), basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC) and cutaneous melanoma (cM) in Dutch outdoor workers (OW) has not previously been investigated. Objective: This study compares the prevalence of premalignant lesions and skin tumours in OW and matched controls (non-OW). Methods: In a population-based cohort study, prevalence of premalignant lesions and skin tumours was investigated in a group of OW (n = 841) and controls matched 1:1 by age, sex, skin colour and tendency for sunburn. Skin examinations were conducted by physicians and skin cancer history was derived from the nationwide Dutch Pathology Registry. Information on OW was obtained through interviews. Conditional logistic regression models were used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for associations between OW and BCC, cSCC, cM and (number of) AK. Results: AK was found in 22.7% of OW and 22.9% of non-OW, BCC in 14% of OW and 15.7% of non-OW, cSCC in 4.9% of OW and 3.4% of non-OW, and cM in 1.9% of OW and 2% of non-OW. There was no significant association between OW and premalignant lesions and skin tumours, with exception for developing ≥4 AKs (OR 1.3 [95% CI 1.0–1.78]). Conclusions: This study reveals high prevalence of premalignant lesions and skin tumours in a Dutch population. No association between OW and the occurrence of premalignant lesions and skin tumours was found, however, multiple AKs were more prevalent in OW.

This systematic review, conducted according to the PRISMA guidelines, focuses on genotoxicity of oxidative hair dye precursors. The search for original papers published from 2000 to 2021 was performed in Medline, Web of Science, Cochrane registry, Scientific Committee on Consumer Safety of the European Commission and German MAK Commission opinions. Nine publications on genotoxicity of p-phenylenediamine (PPD) and toluene-2,5-diamine (p-toluylenediamine; PTD) were included, reporting results of 17 assays covering main genotoxicity endpoints. PPD and PTD were positive in bacterial mutation in vitro assay, and PPD tested positive also for somatic cell mutations in the Rodent Pig-a assay in vivo. Clastogenicity of PPD and PTD was revealed by in vitro chromosomal aberration assay. The alkaline comet assay in vitro showed DNA damage after PPD exposure, which was not confirmed in vivo, where PTD exhibited positive results. PPD induced micronucleus formation in vitro, and increased micronucleus frequencies in mice erythrocytes following high dose oral exposure in vivo. Based on the results of a limited number of data from the classical genotoxicity assay battery, this systematic review indicates genotoxic potential of hair dye precursors PPD and PTD, which may present an important health concern for consumers and in particular for professional hairdressers.

Background: The burden of occupational hand eczema in hairdressers is high, and (partly strong) allergens abound in the hair cosmetic products they use. Objectives: To systematically review published evidence concerning contact allergy to an indicative list of active ingredients of hair cosmetics, namely, p-phenylenediamine (PPD), toluene-2,5-diamine (PTD), persulfates, mostly ammonium persulfate (APS), glyceryl thioglycolate (GMTG), and ammonium thioglycolate (ATG), concerning the prevalence of sensitization, particularly in terms of a comparison (relative risk; RR) between hairdressers and non-hairdressers. Methods: Following a PROSPERO-registered and published protocol, eligible literature published from 2000 to February 2021 was identified, yielding 322 publications, and extracted in standardized publication record forms, also considering risk of bias. Results: Based on 141 publications, the contact allergy prevalence to PPD was 4.3% (95% CI: 3.8–4.9%) in consecutively patch tested patients. Other ingredients were mostly tested in an aimed fashion, yielding variable, and partly high contact allergy prevalences. Where possible, the RR was calculated, yielding an average increased sensitization risk in hairdressers of between 5.4 (PPD) and 3.4 (ATG). Additional evidence related to immediate-type hypersensitivity, experimental results, exposures, and information from case reports was qualitatively synthesized. Conclusions: An excess risk of contact allergy is clearly evident from the pooled published evidence from the last 20 years. This should prompt an improvement in working conditions and product safety.