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The role of domestic water hardness in the development of skin barrier dysfunction and atopic eczema: a systematic review of the literature

Research output: Contribution to journalPoster abstract

Z. Jabbar-Lopez ; V. Phongphit ; C. Y. Ung ; J. Chalmers ; S. Danby ; J. Peacock ; C. Flohr

Original languageEnglish
Pages (from-to)159-159
JournalBritish Journal of Dermatology
Volume177
Issue numberSupp. 1
Early online date3 Jul 2017
DOIs
StatePublished - Jul 2017
EventBritish Association of Dermatologists 97th Annual Meeting, Liverpool, U.K. - Liverpool, United Kingdom

King's Authors

Abstract

[British Society for Paediatric Dermatology and British Society for Allergy & Clinical Immunology joint session. Orals. PA10] Hard domestic water has been reported to worsen atopic eczema (AE) and potentially lead to its development in early life. We conducted a systematic literature review by searching MEDLINE and Embase from inception until October 2016. Human and animal studies were both included. Titles and abstracts were screened and eligible papers reviewed in full. Data were extracted according to a standardized pro forma; 4983 studies were identified and 932 selected for further review. Of these, 10 studies were eligible for inclusion. Studies were not meta-analysed due to methodological heterogeneity. Five cross-sectional studies were identified, conducted in the U.K., Spain, Japan, Denmark and Belgium (n = 358–458 284). All found significant positive associations between high domestic water calcium carbonate levels and AE risk in children, with odds ratios (ORs) ranging between 1.87 and 3.36. One of these studies also suggested that the risk increase was stronger in those carrying a filaggrin skin barrier gene mutation. However, a Spanish birth cohort with 1638 participants did not observe an increased risk of AE with water hardness during 4 years’ follow-up (OR = 0.79, 95% confidence interval 0.45–1.39). Two mechanistic studies in humans found that a higher deposition of the common detergent sodium lauryl sulphate caused skin barrier dysfunction in those exposed to hard vs. softer water. A mechanistic study in 11 dogs with AE washed with shampoo reported improved AE symptoms and skin barrier function with ultrapure soft water vs. hard tap water. Finally, one randomized controlled trial comparing water softeners with standard care in 336 children aged 6 months to 6 years with moderate-to-severe AE did not show a significant improvement in eczema severity with softened water. The majority of observational studies in humans found a positive association between living in a hard-water area and AE. However, once AE is established, using a domestic water softener does not improve disease severity. This does not rule out the potentially important role of water hardness in the initiation of skin inflammation in infancy. We are therefore conducting an intervention study to test whether fitting a water softening device in early life reduces the risk of skin barrier breakdown and AE in high-risk children.

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