Water hardness and mortality in the Netherlands

Area of Science:

• Environmental Health
• Cardiovascular Epidemiology
• Public Health Policy

Background:

• A 1975 Public Health Council recommendation discouraged central water softening based on a negative association between drinking water hardness and Ischemic Heart Disease (I.H.D.) mortality (1958-1970).
• Subsequent research explored the health impacts of central water softening, including metal leaching and nutrient loss during cooking.

Purpose of the Study:

• To re-evaluate the relationship between drinking water hardness and I.H.D. mortality following earlier concerns.
• To investigate potential mechanisms linking water hardness, metal release, and nutrient bioavailability to cardiovascular health.

Main Methods:

• Statistical analysis of I.H.D. mortality rates and drinking water hardness data across multiple municipalities and time periods (1958-1977).
• Investigation of correlations between water calcium levels, metal (Pb, Cu) release from pipes, and water pH.
• Assessment of calcium and magnesium loss from food cooked in water of varying hardness.

Main Results:

• No significant relationship between I.H.D. mortality and drinking water hardness was found for the period 1970-1977 in 30 municipalities.
• An inverse statistical relation between I.H.D. mortality and water hardness persisted in 17 municipalities across three periods (1958-1977), but with decreasing significance.
• Positive correlation observed between water calcium and lead/copper release; negative correlation between hardness and pH.

Conclusions:

• Other factors appear to significantly influence I.H.D. mortality, potentially overriding the effect of water hardness.
• Central water softening to 2-3 meq/l Calcium is unlikely to have a discernible impact on mortality rates.
• Continued research is ongoing to fully elucidate the complex interplay of factors affecting cardiovascular health and water quality.