Changes in water hardness and cardiovascular death rates

Area of Science:

• Environmental epidemiology
• Cardiovascular epidemiology
• Public health

Background:

• Previous research suggested a link between water hardness and cardiovascular death rates.
• A 1951-1961 study by Crawford, Gardner, and Morris indicated an association between water supply hardness and cardiovascular mortality.
• This earlier study faced critical review, necessitating re-evaluation with amended data and methods.

Purpose of the Study:

• To re-examine the relationship between changes in water hardness and cardiovascular death rates.
• To investigate trends in cardiovascular mortality in relation to water hardness in England and Wales between 1961 and 1971.
• To determine if the previously suggested association persists and to assess its specificity to cardiovascular disease.

Main Methods:

• Analysis of changes in water hardness data for county boroughs in England and Wales.
• Analysis of changes in cardiovascular death rates for the same population and time period (1961-1971).
• Statistical trend analysis to identify correlations between water hardness and mortality rates, stratified by sex.

Main Results:

• A significant trend was observed for men, showing decreased cardiovascular mortality with increased water hardness.
• No significant trend was found for women regarding cardiovascular mortality and water hardness.
• The observed trend in male mortality appeared specific to cardiovascular disease, not general mortality.

Conclusions:

• The findings support the hypothesis of a weak causal relationship between drinking water hardness and cardiovascular disease mortality.
• The results are consistent with earlier studies, reinforcing the potential impact of water composition on public health.
• Further research may be warranted to elucidate the mechanisms behind this association and its sex-specific differences.