Medical Hydrology and Balneology: Environmental Aspects

Nitrates in spanish waters: natural mineral
water and tap water
Armijo F (1-2) , Corvillo I (1-2) , Vazquez I (3) , Vitoria I (4) , Maraver F (1-2)
(1) Professional School of Medical Hydrology, Faculty of Medicine, Universidad
Complutense de Madrid, Madrid, Spain
(2) Department of Physical Medicine and Rehabilitation. Medical Hydrology, Faculty of
Medicine, Universidad Complutense de Madrid, Madrid, Spain
(3) Geological Survey of Spain (IGME), Tres Cantos-Madrid, Spain
(4) Unidad de Nutrición y Metabolopatías. Hospital La Fe. Valencia, Spain.
farmijoc@med.ucm.es
For over three decades, the Chair of Medical Hydrology, Faculty of Medicine,
Universidad Complutense de Madrid has studied the waters of Spanish spas 1 , bottled
waters 2 and the spring water of several Spanish areas 3 .
In this paper we have done the full analysis, from the Medical Hydrology point
of view, of 97 bottles of mineral water and of 117 samples of tap water from towns
with a population over 50,000, paying special attention to the nitrate concentration.
In recent years, the level of nitrogen in soils is much higher than necessary so
the excess nitrate easily filters and reaches the aquifer; plants absorb more nitrates
than necessary accumulating larger amounts of nitrates than usual. This can determine
serious implications for health and for the environment.
Nitrates are natural constituents of vegetables and can be found in very high
concentrations. Natural spinach or celery can contain as much as 2 g/kg of nitrate.
Nitrates may also be present in other vegetables, such as beets or chard, as well as
in the drinking water.
The World Health Organization (WHO) establishes the maximum value of 50
mg/L of "nitrate ion" in the drinking water. This limit was chosen to prevent a
serious problem due to toxic nitrates / nitrites levels in children under four months 4 .
The toxic effects of nitrates are due to its reduction to nitrite. Excessive amounts
of nitrates in water can have lethal effects because of metahemoglobin formation in
infants, and nitrosamines (carcinogenic) formation, due to a reaction between the
nitrates with amines and amino acids, in adults 5 .
In pregnant women, some studies have suggested a relation between exposure to
nitrates in water and spontaneous abortions, intrauterine growth retardation and
multiple congenital defects. However, epidemiological evidence has not yet been
sufficiently demonstrated 6-7-8 .
Balnea
2012, núm. 6, 220-222
220
ISBN: 978-84-669-1887-0
978-84-669-3482-4