Academic journal article Journal of Health Population and Nutrition

Spatial and Temporal Variations in Arsenic Exposure Via Drinking-Water in Northern Argentina

Academic journal article Journal of Health Population and Nutrition

Spatial and Temporal Variations in Arsenic Exposure Via Drinking-Water in Northern Argentina

Article excerpt

INTRODUCTION

Arsenic is ubiquitous in the environment and is usually present in small amounts (1.5-2 mg/kg) in the bedrock. However, the concentrations vary considerably, and leakage from naturally-occurring arsenic-rich minerals and sediments to ground water is a growing public-health problem worldwide. Millions of people in Asia, the American continent, and Europe are exposed to arsenic concentrations in drinking-water that far exceed the drinking-water quality guideline of 10 [micro]g/L recommended by the World Health Organization (1,2).

High levels of arsenic in ground water have previously been reported from several areas in Argentina, particularly in the Puna region in the Andes, the Chaco region, Cordoba, and the Pampean Plain (3-8). In la Francia, Cordoba, concentrations of arsenic as high as 3,000 [micro]g/L in groundwater were recorded (3) and up to 600 [micro]g/L in the Pampean Plain (4). It was reported that the number of locations with elevated arsenic concentrations of natural origin in water continued to grow. In addition, food may contain elevated arsenic concentrations (9-11).

The aim of the present study was to evaluate variations in human exposure to arsenic in the Puna region in the Andes in northwestern Argentina and the Chaco Salteno region in the north of Argentina, based on the studies we have carried out in the area over a 10-year period (9,12) and on recent follow-up studies. We assessed arsenic exposure based on arsenic concentrations in drinking-water, urine, and hair to obtain as much information as possible on the exposure situation and dose. Urine is the major route of excretion of absorbed arsenic, and the concentration of arsenic in urine is commonly used for the evaluation of current exposure to arsenic on an individual level. In the case of continuous arsenic exposure via drinking-water, urinary excretion of arsenic is remarkably constant over time (13,14). Inorganic arsenic binds to sulphydryl groups in the body, e.g. keratin in hair. Therefore, arsenic in hair is a useful biomarker of more long-term arsenic exposure (15).

MATERIALS AND METHODS

Study sites and subjects

The Puna is an arid highland surrounded by a mountain belt in the central part of the Andes, in the province of Salta in northern Argentina. The temperature varies from about -26 [degrees]C in July to about +30 [degrees]C (daytime) in December. The volcanic bedrock has a high content of arsenic associated with pyrite minerals (16). The main part of the study was conducted in San Antonio de los Cobres, with about 5,000 inhabitants, mainly indigenous, at an altitude of 3,800 m. The local economy is based on breeding of llamas, goats, and sheep. The staple diet of the population is mainly of animal origin (meat, milk), supplemented with vegetables, maize, and rice. The source of drinking-water in San Antonio de los Cobres is a natural spring, Agua de Castilla, located about one km outside the village. Arsenic exposure was also studied in the small Puna communities-Olacapato, Santa Rosa de los Pastos Grandes, and Tolar Grande (each with less than 200 inhabitants), located 60-187 km southwest and west of San Antonio de los Cobres.

The Chaco Salteno region is a semi-arid area located in the southeast of the province of Salta. Taco Pozo has 8,500 inhabitants; Joaquin V Gonzalez, a village located only a few km from Taco Pozo, has about 13,400 inhabitants, and Anta has about 400 inhabitants. The climate is much warmer than in the Andes, particularly in the winter. The most important industries are related to the production of cotton, tobacco, and wood, and the breeding of cattle, goats, and pigs, combined with the growing of maize, pumpkins, and squash. Most people use well-water either from private wells or from the public distribution system. For comparison, we also determined arsenic exposure in Salta, the capital of the province (at an altitude of about 1,000 m) and the nearby village Rosario de Lemma. …

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