DRINKING WATER HARDNESS AND CARDIOVASCULAR DISEASES

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DRINKING WATER HARDNESS AND CARDIOVASCULAR
DISEASES

• A REVIEW OF EPIDEMIOLOGICAL STUDIES

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REBECCA L. CALDERON National Health and
Environmental Effects Research Laboratory, U.S.
EPA GUNTHER F. CRAUN Gunther F. Craun
Associates gfcraun_at_verizon.net
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Cardiovascular Disease (CVD)

• morbidity and mortality varies worldwide
• major risk factors do not entirely explain the
  variability
• Is CVD associated with water hardness?

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Hypothesis

• hard water or minerals, such as calcium (Ca) and
  magnesium (Mg) found in hard water, may help
  decrease cardiovascular risks
• constituents associated with soft waters (e.g.,
  corrosion products from distribution pipes,
  sodium from home softening units) may increase
  the risk

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Epidemiological studies of CVD and water
hardness, Ca, and Mg

• 60 ecological studies population based
• 7 case-control studies individuals
• 2 cohort studies individuals

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Population-based studies

• Geographical correlation, group, or aggregate
  studies
• explore relationships between available health
  statistics (e.g., CVD) and population
  characteristics (e.g., environmental and water
  quality measures)
• associations characterize population risks

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Studies of individuals

• Obtain information about disease and exposures
  from each study participant
• Test specific hypotheses
• Provide a quantitative estimate of the relative
  risk
• Provide information to help scientists assess
  causality

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CONCLUSIONS
Hardness, as such, and decreased CVD risk No
evidence for an association
Calcium in drinking water and decreased CVD
risk Limited evidence of an association
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CONCLUSIONS
Magnesium in water and decreased CVD
risk Reduction in CVD risk with increasing Mg
levels in drinking water
Low intake of Mg from DW increases the risk of
dying from and possibly developing CVD or
stroke Findings supported by evidence
from toxicological and dietary studies
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Geographical correlation studies

• 60 in 21 cities and various countries including
• U.S., England and Wales, Taiwan, South
  Africa, France, Canada, Sweden, Irish Republic
  and Northern Ireland, Netherlands, Norway,
  Finland, Italy, Rumania, Bohemia and Moravia,
  Scotland, Germany, Japan, Australia, and Hungary

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Geographical correlation studies

• Four studies estimated the effect of drinking
  water hardness

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England and Wales

• 7.5 reduction of CVD mortality (men) for 100
  mg/l increased water hardness

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France

• 10 reduction of the risk for CVD mortality for
  the highest Ca concentration (94-146 mg/l) and
  highest Mg concentration (11-34 mg/l) compared
  to the lowest concentrations

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Finland

• The risk of Acute Myocardial Infarction (AMI)
  decreased 1.1 for each 20 mg/l increase in water
  hardness

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Taiwan

• 10 increase in the risk of Ischemic heart
  disease (IHD) mortality with hardness compared to persons with 150 mg/l
  hardness

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Case-control studies

• 5 of 7 studies - a significant protective
  association between Mg levels in DW and mortality
  for AMI, stroke, or hypertension
• One study a significant protective association
  between AMI and both Ca and Mg levels in DW
• Studies in Finland, Taiwan, and Sweden

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Finland AMI

• AMI mortality risk decreased among men as
  drinking water
• Mg levels increased from 3
  mg/l

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Taiwan Stroke

• Taiwan, 252 municipalities with single water
  source 1989-1993
• 17,133 males and females dead for stroke (cases)
• 17,133 males and females dead for other causes,
  excluding CVD (controls)
• age50-69

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Taiwan Stroke
Significant decreased risk of death from stroke
among men and women associated with drinking
water levels of Mg 7.4 mg/l
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Taiwan Hypertension

• Taiwan, 252 municipalities with single water
  source 1990-1994
• 2,336 males and females dead for hypertension
  (HT) (cases)
• 2,336 males and females dead for other causes,
  excluding CVD (controls)
• age50-69

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Taiwan Hypertension
Significant decreased risk of death due to
hypertension associated with Mg 3.8
mg/l Exposure-response relationship (p 22
Sweden AMI

• Study conducted by Rubenowitz et al
• Southern Sweden, 16 municipalities 1982-1983
• 378 females dead for AMI (cases)
• 1,368 females dead for cancer (controls)
• age50-69

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Sweden AMI
Significant decreased risk of death due to
AMI (women) associated with Mg levels 6.9 mg/l .
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Sweden AMI

• Study conducted by Rubenowitz et al
• Southern Sweden, 17 municipalities 1982-1989
• 854 males dead for AMI (cases)
• 989 males dead for cancer (controls)
• age50-69

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Sweden AMI
Significant decreased risk of death due to
AMI (men) associated with Mg levels 6.9 mg/l.
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Southern Sweden AMI

• Rubenowitz et al also conducted a study of
  persons dying from and surviving an AMI
• Conclusion Mg prevents AMI deaths rather than
  incidence

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Sweden AMI

• Rosenlund et al studied AMI risk in 1992-4
• A small, not statistically significant,
  protective effect was associated with a DW Mg
  intake 1.86 mg per day.
• Several limitations including the mean levels of
  Ca and Mg in DW, which were very low compared to
  the levels in other studies

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Cohort Studies Finland

• 15-year follow-up of 1711 men in two rural areas
  of Finland using private well water
• Mortality due to coronary heart disease was 14.7
  in the area with 3-4 mg/l Mg in DW versus 8.7 in
  the area with 13-14 mg/l Mg.
• Almost twice as many deaths with the lower Mg
  level!

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Cohort Studies Maryland

• 12-year study of 30,564 men and women in
  Washington County, Maryland (water hardness 0
  vs. 200 mg/l)
• Water hardness 0 vs. 200 mg/l
• A 14-31 reduced risk of mortality for AHD was
  found in men depending on length of exposure no
  reduced risk for women.

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Epidemiological studies of demineralized water

• Primarily foreign-language literature
• Evaluated by Dr. F. Kozisek
• Extreme case of soft water
• Poses similar risks as soft water

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Recommendation

• Not removing Mg from or increasing Mg intake
  from drinking water may be beneficial -
  especially for populations with an insufficient
  dietary intake of the mineral

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Discussion

• Home softening
• do not soften water at the tap used to obtain
  drinking and cooking water
• Regulations
• US EPA-none
• Europe

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European Guidelines

• Directive (European Union 1980) established a
  requirement for minimum hardness for softened or
  desalinated water ( 60 mg/l as calcium or
  equivalent cations).
• Requirement expired in December 2003. New
  Directive (European Union 1998) does not contain
  the requirement.

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European Guidelines

• Member states may still implement such a
  requirement. Several (e.g. the Netherlands) have
  included Ca, Mg, or hardness into their national
  regulations.
• Four Central European countries that became part
  of the EU in May 2004 have included the
  requirements in their respective regulations but
  vary in binding power.

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Czech Republic

• Binding levels for softened water 30 mg/l Ca
  and 10 mg/l Mg
• Guideline or suggested levels
• 40-80 mg/l Ca and 20-30 mg/l Mg
• (hardness as S Ca Mg 2.0-3.5 mmol/l)

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Hungary

• Binding - minimum required concentration (50
  mg/l) applies to bottled drinking water, new
  water sources, and softened and desalinated water
• Guideline levels hardness 50 350 mg/l
• (as CaO)

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Poland

• Guideline levels hardness 60 500 mg/l
• (as CaCO3)

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Slovakia

• Guideline levels 30 mg/l calcium and
• 10 30 mg/l magnesium.

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Whats next?