Domestic hard water increases eczema prevalence in adults: Study

Australia: Increasing levels of domestic hard water are associated with an increased prevalence of eczema in adults, states an article published in the British Journal of Dermatology.

Some evidence suggests that hard water may damage the skin barrier and lead to the development of eczema. Eczema is a chronic inflammatory skin disease, presented by inflamed, irritated, and itchy skin. Hard water might also worsen symptoms of eczema in people who already have the condition. Domestic water with high mineral content (hard water) is a risk factor for eczema in children, but this association has not been assessed in adults until now.

Diego J., the University of Melbourne, Australia, and his team conducted a study to examine the association between domestic hard water supply and eczema prevalence and incidence in middle-aged adults and the contextual effect on eczema outcomes in adults.

Researchers included 306,531 participants with a mean age of 57 years in the baseline analysis and 31,036 participants for the follow-up analysis. Eczema prevalence at baseline, at follow-up, and incidence (new onset between baseline and follow-up), were determined from the touchscreen questionnaires and nurse-led interviews. Domestic hard water information was obtained from the local water supply companies as calcium carbonate (CaCO3) concentrations. Multilevel logistic regression models with random intercepts were fitted to examine the effect of domestic hard water on eczema outcomes. Researchers also measured the components of variance.

Key findings of the study,

• There was an increase in the odds of eczema at baseline (OR: 1.02) per 50 mg/L of CaCO3 increase.

• Exposure to domestic hard water (>200 mg/L of CaCO3) was associated with increased odds of prevalent eczema at baseline (OR: 1.12).

• There was a significant linear trend in which increasing levels of hard water increased eczema prevalence risk.

• No association was observed with the incident eczema or eczema at follow-up.

• The intraclass correlation coefficient was 1.6% and remained unexplained by area-level socioeconomic measures.

The authors conclude that increasing levels of domestic hard water, as measured by CaCO3 concentrations, are associated with an increased prevalence of eczema in adults but not with increased incidence of the same. Ongoing efforts to reduce hard water exposure may have a beneficial effect in reducing the burden of eczema in adults.

Further research is needed to explore area-level factors that may lead to eczema, the authors suggested

Reference: 

Diego J. Lopez,Ankur Singh,Nilakshi T. Waidyatillake,Dinh S. Bui,Shyamali Dharmage,Caroline J. Lodge,Adrian J. Lowe. First published: 13 July 2022. https://doi.org/10.1111/bjd.21771