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Washing hands with hard water ‘could increase eczema risk’

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Hard water damages the protective skin barrier and could contribute to the development of eczema, according to UK researchers.

Researchers from the University of Sheffield and King’s College London are to embark on a trial to test whether softening the water used to wash babies could reduce the risk of later eczema development, having identified how the process could potentially work.

“Washing with hard water may contribute to the development of eczema”

Simon Danby

They found that exposing the skin to hard water damaged the skin barrier and increased the sensitivity of the skin to potential irritants found in everyday washing products, such as soap or washing powder.

They noted that hard water contained high levels of calcium and magnesium ions that bind to surfactants such as sodium lauryl sulfate and sodium lauryl ether sulfate – which act as detergents or wetting agents – making them insoluble, so they precipitate onto the skin.

Skin pH is normally acidic but hard water has high alkalinity, which means it can raise the skin surface pH, they said, meaning a shift towards alkaline pH disturbs the skin’s natural function as a physical barrier and leaves it prone to colonisation by potentially pathogenic bacteria which can cause infection.

Lead study author Dr Simon Danby from Sheffield University’s department of infection, immunity and cardiovascular disease, said: “By damaging the skin barrier, washing with hard water may contribute to the development of eczema.

University of Sheffield

Washing hands with hard water ‘could increase eczema risk’

Simon Danby

“Patients with eczema are much more sensitive to the effects of hard water than people with healthy skin,” he said. “This increase in sensitivity is associated with a genetic predisposition to a skin barrier defect brought about by mutations in the gene encoding filaggrin.

“Filaggrin is a structural protein important for the formation of our skin’s barrier to the outside environment. Up to half of all people with eczema carry a filaggrin gene,” noted Dr Danby.

He added: “This new study reveals the mechanism by which calcium and magnesium ions in hard water, surfactants, and filaggrin interact to damage the skin barrier unlocking new information about how exposure to hard water could potentially contribute to the development of eczema.”

The researchers examined whether removing the calcium and magnesium ions using an ion-exchange water softener could mitigate the negative effects of hard water on the skin.

Using a water softener reduced the harmful effects of surfactants, potentially decreasing the risk of developing eczema, according to their findings published this week in the Journal of Investigative Dermatology.

“One in five children and one in 12 adults in the UK suffer from eczema”

Carsten Flohr

Co-senior study author Dr Carsten Flohr, from the St John’s Institute of Dermatology at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London, said: “One in five children and one in 12 adults in the UK suffer from eczema, costing the NHS well over £500m annually.

“It is during the first few days and months of life that our skin is most susceptible to damage and most at risk of developing eczema,” he said.

“For that reason, we are now embarking on a pilot trial to investigate whether installation of a domestic water softener around the time of birth can prevent skin barrier breakdown and eczema in those living in hard water areas,” he added.

The Softened Water for Eczema Prevention (SOFTER) trial will be undertaken by King’s College London and the National Institute for Health Research’s biomedical research centre at Guy’s and St Thomas’.

They will work in collaboration with the University of Sheffield team and colleagues from the University of Dundee, Nottingham University, Imperial College London, the US National Institute for Health and Amsterdam Medical Centre.



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