The impact of working conditions and constitutional factors on the onset of hand contact dermatitis in dental medicine doctors and medical doctors Introduction: The most common occupational skin diseases (OSD) are irritant and allergic contact dermatitis (CD) on the skin of the hands, and the most significant occupational risk factors responsible for their occurrence are contacts with irritants (most commonly contact with water during work) and allergens at the workplace. Among occupational CD, the most common is irritant CD (about 80 %), which is therefore the most common cause of hand eczema. According to available data, there are very few officially reported OSDs in the Republic of Croatia, predominantly allergic CD. It is unclear whether it is a result of a real situation or is it an issue of underreporting. Aim: Since, according to the available literature data, the population of dental medicine doctors (DMD) and medical doctors (MD) of the non-surgical and surgical professions has not been specifically compared, nor has the study of the impact of surgical work on occupational CD been conducted, this research is the first of its kind. The purpose of this study was to determine the prevalence of hand CD in DMDs and MDs of the surgical and non-surgical professions in relation to persons not occupationally exposed to skin irritants/allergens, to determine environmental and constitutional factors affecting the onset and course of CD and their relationships. Participants and methods: The study involved 185 participants, that is 5 groups that included 37 subjects each: 1) DMDs surgeons; 2) DMDs of non-surgical professions; 3) MDs surgeons; 4) MDs of non-surgical professions; 5) a control group of employed adults without professional exposure to skin irritants and/or allergens that correspond to groups of health professionals by gender, age, education level and occupation (working with people). The study was conducted at the Clinical Department of Dermatovenereology of the University Hospital Center “Sestre milosrdnice”; School of Dental Medicine, University of Zagreb; Clinical Hospital “Dubrava”; Dental Polyclinic Zagreb (“Perkovčeva”) and Institute for Medical Research and Occupational Health. The study was designed as a cross-sectional field study. The study included: 1) taking data with a modified Nordic Occupational Skin Questionnaire (NOSQ) questionnaire (questionnaire translation) with added questions about working conditions, self-reportred atopy manifestations and skin dryness, with addition of a Scale of Perceived Stress, Zung Self-rating Anxiety Scale and additional questions about working hours; 2) physical examination of the skin of the hands by a specialist of dermatovenereology (from main institution), which included an assessment of the severity of the skin changes on hands according to the Osnabrueck hand eczema severity index (OHSI) and assessment of skin type according to the Fitzpatrick skin type scale; 3) allergy skin testing - standard skin prick test (SPT) and standard patch test (PT). SPT was performed with commercial solutions of the most common inhalant allergens [(blend of pollen grass, birch pollen, hazel pollen, Ambrosia artemisiifolia; mites Dermatophagoides pteronyssinus, cat hair (Diater laboratorio, Spain) and latex (Stallergenes, France)], and PT with commercial contact allergens (thiuram compounds, mercapto compounds, carba compounds, methylisothiazolinone+methylchloroisothiazolinone, triethylene glycol dimethacrylate, N-isopropyl-N-phenyl-4-phenylenediamine (IPPD), methyl methacrylate, 2-hydroxyethyl methacrylate, ethylene glycol dimethacrylate; Chemotechnique Diagnostics, Sweden) by using IQ Ultimate™ patch test units (Chemotechnique Diagnostics, Sweden) and ICDRG (International Contact Dermatitis Research Group) criteria for interpreting the results; 4) measurement of skin surface pH and transepidermal water loss (TEWL) on the skin of hand and forearm in standarized manner using commercial devices (Probe Tewameter® TM 300, Probe Skin-pH-Meter® PH 905, Courage+Khazaka electronic GmbH, Cologne, Germany). Results: The highest prevalences of self-reported and objectively (by clinical hands examination) determined hand eczema (HE) were found in DMDs (surgeons and non surgeons) and DMs of surgical professions and ranged between 37.8 % and 56.8 %, indicating that these groups of health professionals are at high risk for the development of HE. HE in the analyzed groups of health professionals was significantly associated only with exposure to specific skin irritants in the workplace, specifically with wearing protective gloves for a longer periods of time daily, as the most significant independent risk factor, which indicates that in the case of HE in our respondents, it is mostly about developing an occupational skin disease. TEWL as a parameter of skin barrier function proved to be a possible indicator of early damage to the skin barrier by irritation due to wearing gloves, since, as significant predictors for higher TEWL values of hands were dental profession and male gender which dominated in surgical groups, and for these categories of respondents, wearing protective gloves for longer periods of time during the working day was found. Atopy and the presence of atopic diseases, especially atopic dermatitis (AD), in this study did not prove to be a predictor of objectively established HE in the analyzed groups of health professionals, suggesting a possibility of a “healthy worker” effect. Self-reported AD was more related to the occurrence of HE in control group. Given that the control group is not exposed to irritants/allergens in their daily work, it is likely that the HE in this group is not a reflection of the development of OSD. It is rather possible that it is AD or non-occupationally caused CD. Also, the results of this study do not suggest increased levels of workplace stress as a factor associated with the occurrence of objectively established HE in analyzed groups of healthcare professionals. Conclusion: Healthcare workers, that are DMDs and MDs, especially of surgical specialties, are at increased risk of developing professional CD. As almost every other person in these groups had changes on the skin of the hands, special attention should be paid to designing and implementing preventive measures in this group of healthcare workers.