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SPECIAL REPORT ActaDV ActaDV Advances in dermatology and venereology Acta Dermato-Venereologica
Debunking the Myth of Wool Allergy: Reviewing the Evidence for Immune and Non-immune Cutaneous Reactions
Michaela ZALLMANN 1, 2, Pete K. SMITH 3, Mimi L. K. TANG 2, 4, 5, Lynda J. SPELMAN 6, Jennifer L. CAHILL 7, Gabriele WORTMANN 8, Constance H. KATELARIS 9, Katrina J. ALLEN 2, 4, 5 and John C. SU 1, 2, 4, 5
1
Department of Dermatology, Monash University, Eastern Health, Box Hill, Victoria, 2 Murdoch Childrens Research Institute, Melbourne, Victoria,
3
School of Medicine, Griffith University, Gold Coast and Bond University Medical School, Robina, Queensland, 4 Department of Paediatrics, The Royal Children’ s Hospital, Melbourne, Victoria, 5 Department of Paediatrics, University of Melbourne, Melbourne, Victoria, 6 Queensland Institute of Dermatology and Veracity Clinical Research, Brisbane, Queensland, 7 The Skin and Cancer Foundation Inc., Melbourne and Department of Dermatology, Alfred Health, Melbourne, Victoria, Australia, 8 The School of Materials, The University of Manchester, Manchester, United Kingdom, and 9 Department of Medicine, Campbelltown Hospital and School of Medicine, Western Sydney University, New South Wales, Australia
Although wool is commonly believed to cause irritant( non-immune) and hypersensitivity( immune) cutaneous reactions, the evidence basis for this belief and its validity for modern garments have not been critically examined. Publications from the last 100 years, using MEDLINE and Google Scholar, were analysed for evidence that wool causes cutaneous reactions, both immune-mediated( atopic dermatitis exacerbation, contact urticaria, allergic contact dermatitis) and non-immune-mediated( irritant contact dermatitis, itch). Secondary aims of this paper were to examine evidence that lanolin and textile-processing additives( formaldehyde, chromium) cause cutaneous reactions in the context of modern wool-processing techniques. Current evidence does not suggest that wool-fibre is a cutaneous allergen. Furthermore, contact allergy from lanolin, chromium and formaldehyde is highly unlikely with modern wool garments. Cutaneous irritation from wool relates to high fibre diameters( ≥ 30 – 32 µ m). Superfine and ultrafine Merino wool do not activate sufficient c-fibres to cause itch, are well tolerated and may benefit eczema management.
Key words: wool; allergy; atopic dermatitis; contact dermatitis; irritant dermatitis.
Accepted Mar 22, 2017; Epub ahead of print Mar 28, 2017 Acta Derm Venereol 2017; 97: 906 – 915.
Corr: Dr Michaela Zallmann, Department of Dermatology, Eastern Health, Faculty of Medicine, Monash University, Clayton Campus, 5 Arnold Street, Box Hill, Victoria, Australia 3128. E-mail: m. zallmann @ gmail. com
Wool is frequently perceived by the general community as being prickly and itchy, two qualities that correlate with perceived textile intolerance( 1, 2). In a longitudinal global consumer survey( 2012 – 2015) of 3,591 respondents, commissioned by Australian Wool Innovation( AWI), 43 % of consumers who declared they would not consider purchasing woollen garments believed wool to be too itchy, prickly or uncomfortable( 3). Similarly, in the medical community, avoidance of wool garments in favour of cotton has been advocated for patients with atopic dermatitis( AD) dating back to before 1980 when wool intolerance was included as a minor criterion in the Hanifin & Rajka( 4) diagnostic criteria for AD. However, the updated criteria for AD excludes wool intolerance as a diagnostic feature. It is now recognised that sensations of itch and prickle occur as a result of fibre properties, especially coarse fibre diameter(> 30 – 32 µ m), common across many fibre types rather than properties specific to wool( 5 – 7). Despite this, wools’ reputation as a cutaneous irritant, in both medical and public arenas, remains common, and wool avoidance is frequently recommended by medical professionals, particularly to patients with AD.
In addition to concerns about irritancy, wool is frequently perceived as an allergen in the general community. The aforementioned AWI-commissioned survey showed that 9 % of consumers reported avoidance of wool garments because of self-identified wool allergy( 3). Among the public, wool-evoked prickle and skin irritation are commonly attributed to allergy to wool, despite not being immunologically mediated( 8 – 10). Heightened focus has been placed on allergy in both public and medical domains following evidence of exponential growth in IgE mediated allergic disease( AD, asthma, allergic rhinitis and food allergy) since the 1990’ s, particularly in western countries( 11). The prevalence of AD amongst children under 17 years in the 2003 National Survey of Children’ s Health ranged from 9.7 – 18.1 % across the USA( 12). By comparison, in 2015, 28.0 % of the Australian HealthNuts population-based cohort of 5,276 children, had a history of infantile AD, and 20.3 % had clinically documented signs of AD at 12 months( 13). Although wool is commonly considered to be an allergen, there is a lack of high quality evidence to support this.
Several authors from the early 20 th century reported cases of dermatitis and urticaria allegedly resulting from wool sensitisation and allergy( 9, 14 – 21). These reports have been cited in subsequent papers as evidence of the allergenicity of wool. However, the findings from these publications should be interpreted with caution due to limitations and inconsistencies in methodology hitherto doi: 10.2340 / 00015555-2655 Acta Derm Venereol 2017; 97: 906 – 915
This is an open access article under the CC BY-NC license. www. medicaljournals. se / acta Journal Compilation © 2017 Acta Dermato-Venereologica.