27th September 2017 – Living in a hard water area could increase your risk of developing eczema, say scientists.
A research team from the University of Sheffield and King's College London say hard water compromises the protective skin barrier and makes our skin more liable to damage from soap and washing powders.
They say skin is most at risk in the early years of life and are keen to discover whether infants should be protected from exposure to hard water.
Water in different areas of the UK varies because of the amount of dissolved minerals it contains. Hard water – common in the south-east of England – contains high levels of calcium and magnesium absorbed from the rocks that rainwater passes through.
These minerals bind to detergents and wetting agents, making them insoluble and causing them to build up on the skin. Many people will be familiar with how this makes creating a lather more difficult in hard water areas, compared with soft water areas.
Skin is normally acidic but hard water is alkaline, and this can raise the skin surface pH – a measure of alkalinity or acidity.
Bacteria and infection
The researchers say this shift towards alkalinity disturbs the protective nature of skin and leaves it vulnerable to being colonised by potentially damaging bacteria that can lead to infection.
The study, funded by Harvey Water Softeners and published in the Journal of Investigative Dermatology, says that people with eczema are much more sensitive to the effects of hard water than those with healthy skin. They suggest this increase in sensitivity is associated with genetic mutations that bring about a skin barrier defect.
Itchy, irritated skin
Eczema – also known as atopic eczema – is an inflammatory skin condition. Symptoms include inflamed, dry skin that causes itching.
It is most common in children, affecting at least 10% of infants at some stage. It usually disappears during childhood, although it can affect older people. Many people who have experienced eczema continue to have dry skin and need to avoid irritants, including soaps.
The study involved 80 people with and without eczema who washed with sodium lauryl sulfate – a chemical commonly found in soaps, shampoos and detergents – in hard water or water that had been filtered through a water softening device.
The scientists conclude that "washing the skin with hard water increases exposure to potentially irritant metallic surfactants that can impair the functioning of the skin barrier, especially in people with a predisposition to a skin barrier defect".
The team says one drawback of their investigation is the small number of people involved in the trial. They now want to investigate whether using softer water around the time of birth can reduce the likelihood of developing early eczema in hard water areas.
A 'significant trigger'
The National Eczema Society has welcomed the research. Its chief executive, Margaret Cox, tells us by eail: "Observationally many of us living with the condition have long suspected that for those of us genetically predisposed to atopic eczema, a combination of harsh wash products containing soap and detergents and hard water were a very significant trigger factor and it is interesting to see this confirmed by this mechanistic study.
"Avoiding harsh wash products is important in keeping eczema at bay and it will be interesting to see whether additionally using an ion exchange water softener for babies in high risk families has an impact on reducing the incidence of the condition."
She says previous research has established that water softeners are of no benefit in reducing symptoms for people who already have eczema.
The Effect of Water Hardness on Surfactant Deposition Following Washing and Subsequent Skin Irritation in Atopic Dermatitis Patients and Healthy Controls, Danby S et al, Journal of Investigative Dermatology
Press releases: University of Sheffield; King's College London
Margaret Cox, chief executive, National Eczema Society
British Skin Foundation
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