Arsenic in public water supplies and cardiovascular mortality in Spain.
BACKGROUND
High-chronic arsenic exposure in drinking water is associated with increased cardiovascular disease risk. At low-chronic levels, as those present in Spain, evidence is scarce. In this ecological study, we evaluated the association of municipal drinking water arsenic concentrations during the period 1998-2002 with cardiovascular mortality in the population of Spain.


METHODS
Arsenic concentrations in drinking water were available for 1721 municipalities, covering 24.8 million people. Standardized mortality ratios (SMRs) for cardiovascular (361,750 deaths), coronary (113,000 deaths), and cerebrovascular (103,590 deaths) disease were analyzed for the period 1999-2003. Two-level hierarchical Poisson models were used to evaluate the association of municipal drinking water arsenic concentrations with mortality adjusting for social determinants, cardiovascular risk factors, diet, and water characteristics at municipal or provincial level in 651 municipalities (200,376 cardiovascular deaths) with complete covariate information.


RESULTS
Mean municipal drinking water arsenic concentrations ranged from <1 to 118 microg/L. Compared to the overall Spanish population, sex- and age-adjusted mortality rates for cardiovascular (SMR 1.10), coronary (SMR 1.18), and cerebrovascular (SMR 1.04) disease were increased in municipalities with arsenic concentrations in drinking water > 10 microg/L. Compared to municipalities with arsenic concentrations < 1 microg/L, fully adjusted cardiovascular mortality rates were increased by 2.2% (-0.9% to 5.5%) and 2.6% (-2.0% to 7.5%) in municipalities with arsenic concentrations between 1-10 and >10 microg/L, respectively (P-value for trend 0.032). The corresponding figures were 5.2% (0.8% to 9.8%) and 1.5% (-4.5% to 7.9%) for coronary heart disease mortality, and 0.3% (-4.1% to 4.9%) and 1.7% (-4.9% to 8.8%) for cerebrovascular disease mortality.


CONCLUSIONS
In this ecological study, elevated low-to-moderate arsenic concentrations in drinking water were associated with increased cardiovascular mortality at the municipal level. Prospective cohort studies with individual measures of arsenic exposure, standardized cardiovascular outcomes, and adequate adjustment for confounders are needed to confirm these ecological findings. Our study, however, reinforces the need to implement arsenic remediation treatments in water supply systems above the World Health Organization safety standard of 10 microg/L.
Medrano
M A José
MA
Centro Nacional de Epidemiología, Instituto de Salud Carlos III, Sinesio Delgado 6, 28029 Madrid, Spain.
Boix
Raquel
R
Pastor-Barriuso
Roberto
R
Palau
Margarita
M
Damián
Javier
J
Ramis
Rebeca
R
Del Barrio
José Luis
JL
Navas-Acien
Ana
A
D000368:Aged; D001151:Arsenic / Q000032:analysis*; D002318:Cardiovascular Diseases / Q000401:mortality*; D004326:Drinking; D004781:Environmental Exposure / Q000032:analysis / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D008297:Male; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data; D014881:Water Supply / Q000032:analysis* / Q000706:statistics & numerical data
D014874:Water Pollutants, Chemical; D001151:Arsenic