Environ. Sci. Technol. 2010, 44, 6875–6880
High-Level Exposure to Lithium, Boron, Cesium, and Arsenic via Drinking Water in the Andes of Northern Argentina GABRIELA CONCHA,† KARIN BROBERG,‡ ´ R,§ MARGARETHA GRANDE ALEJANDRO CARDOZO,| BRITA PALM,§ A N D M A R I E V A H T E R * ,§ Division of Toxicology, Swedish National Food Administration, Box 622, S-751 26 Uppsala, Sweden, Division of Occupational and Environmental Medicine, Lund University, S-221 85 Lund, Sweden, Institute of Environmental Medicine, Karolinska Institutet, Box 210, S-171 77 Stockholm, Sweden, and Hospital Dr Nicola´s Cayetano Pagano, 4411 San Antonio de los Cobres, Departamento Los Andes, Provincia de Salta, Argentina
Received April 1, 2010. Revised manuscript received July 1, 2010. Accepted July 27, 2010.
Elevated concentrations of arsenic in drinking water are common worldwide, however, little is known about the presence of other potentially toxic elements. We analyzed 31 different elements in drinking water collected in San Antonio de los Cobres and five surrounding Andean villages in Argentina, and in urine of the inhabitants, using ICP-MS. Besides confirmation of elevated arsenic concentrations in the drinking water (up to 210 µg/L), we found remarkably high concentrations of lithium (highest 1000 µg/L), cesium (320 µg/L), rubidium (47 µg/ L), and boron (5950 µg/L). Similarly elevated concentrations of arsenic, lithium, cesium, and boron were found in urine of the studied women (N ) 198): village median values ranged from 26 to 266 µg/L of arsenic, 340 to 4550 µg/L of lithium, 34 to 531 µg/L of cesium, and 2980 to 16 560 µg/L of boron. There is an apparent risk of toxic effects of long-term exposure to several of the elements, and studies on associations with adverse human health effects are warranted, particularly considering the combined, life-long exposure. Because of the observed wide range of concentrations, all water sources used for drinking water should be screened for a large number of elements; obviously, this applies to all drinking water sources globally.
Introduction The availability of sufficient amounts of clean water is becoming one of the major public health issues worldwide, as pointed out in the seventh UN Millenium Goal. In many areas, surface water is lacking or is highly polluted, and people are increasingly dependent on groundwater as drinking water. Already now, about one-third of the people on earth are dependent on groundwater for their drinking water supplies. * Corresponding author tel: +46-8-7287540; fax: +46-8-336981; e-mail:
[email protected]. † Swedish National Food Administration. ‡ Lund University. § Karolinska Institutet. | Hospital Dr Nicola´s Cayetano Pagano. 10.1021/es1010384
2010 American Chemical Society
Published on Web 08/11/2010
In general, groundwater is much less contaminated by anthropogenic actions and it is generally believed to be suitable for drinking purposes. However, many different minerals in the ground may dissolve potentially toxic metals into the surrounding aquifer. Arsenic is a potent carcinogen and general toxicant. High levels of arsenic in groundwater have been reported from many areas in the world, and because of the increasing use of groundwater for drinking purposes, the number of people with elevated arsenic exposure continues to grow. In addition, there is increasing concern about elevated concentrations also in locally grown food of plant origin, e.g., rice, maize, beans, and root and leafy vegetables (1–3). In Argentina, elevated concentrations of arsenic in groundwater have been detected particularly in the Puna region in the Andes, the Chaco region, Co´rdoba, and the Pampean Plain (4–6). We have previously reported on the extensive variation in arsenic exposure via drinking water and food in people living in some Puna villages in the Argentinean Andes (7–9). The aim of the present study was to assess human exposure to other elements through drinking water in the same area. We measured concentrations of a range of potentially toxic and essential elements in drinking water and urine. Urine is the major route of excretion of absorbed arsenic and several other elements and is commonly used for the evaluation of current exposure on an individual level.
Materials and Methods Study Site and Subjects. The Puna is an arid highland surrounded by mountains in the central part of the Andes, where the volcanic bedrock has high content of several minerals (10). The climate is characterized by cold winters, about -25 °C in July, with sparse rain, and dry and warm summers with a daytime temperature of about +30 °C in December. The main part of the study was conducted in San Antonio de los Cobres, province of Salta, situated at an altitude of 3800 m, 66.39° W and 24.24° S (Figure 1). The village has about 5000 inhabitants, mainly of indigenous origin. The local economy in this region is based on breeding of llamas, goats, and sheep. The staple diet 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 1 km outside the village. We have repeatedly reported elevated arsenic concentration in this water (7, 8, 11), but no mitigation efforts have been implemented. We also screened for arsenic exposure through drinking water in the small Puna communities Olacapato, Salar de Pocitos, and Tolar Grande (each with less than 200 inhabitants), located 60-187 km southwest and west of San Antonio de los Cobres (Figure 1). The present study assessed the exposure to other, potentially toxic elements among about 200 women in this area. We focused on women, who spend more time in the village home than men, who often are far away for work for longer periods of time. In San Antonio de los Cobres, women were recruited via the local physicians and community health workers at the hospital. In the other villages, women were recruited with the assistance of personnel at the local health centers. Although it was not possible, for practical reasons, to select the women at random (except in Tolar Grande), measures were taken to get as wide a distribution of households as possible. The women were interviewed about sources of drinking water, amounts of water consumed, dietary habits, and time of residence in the area. The water intake was estimated from the number of glasses of water VOL. 44, NO. 17, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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FIGURE 1. Study locations in Argentina.
consumed daily. A spot urine sample was obtained from all women. All women gave informed consent and the study was approved by the Ministry of Health in Salta, Argentina, and the ethical committee at Karolinska Institute, Sweden. Sample Collection and Measurement of Elements. Exposure was assessed by measuring element concentrations in water and urine. Drinking water was collected from the public water-distribution systems or private wells in 20-mL acid-washed polyethylene bottles after flushing the water for about 1 min. To acidify the water samples, an aliquot of 100 µL of concentrated nitric acid (p.a. Merck, Germany) was added. Spot-urine samples were collected in disposable urine collection cups and immediately transferred to 20-mL acid-washed polyethylene bottles. After sampling, the pH and the presence of protein in the urine were tested using N-Combur-Test (Boeringer Mannheim GmbH, Germany). All urine and water samples were kept at -20 °C until they were transported together with cooling blocks to Sweden for analysis. The samples were analyzed within a couple of months. Analysis of Elements. Water and urinary concentrations of 31 different elements were determined using inductively coupled plasma mass spectrometry (ICPMS; Agilent 7500ce, Agilent Technologies, Waldbronn, Germany) with a collision/ reaction cell system. The gas modes used are reported in Table 1. The ICP-MS operation details have been described previously (12, 13). Standard solutions for the external calibrations (Merck VI, Darmstadt, Germany; CPI International, Amsterdam, Netherlands; Ultra Scientific Analytical Solutions, North Kingstown, RI) and internal standards (CPI International, Amsterdam, Netherlands) were prepared fresh before every run in 1% nitric acid (65% suprapur, Merck, Darmstadt, Germany). All the samples contained the measured elements in concentrations well above their calculated limit of detection (3 times the SD of the blank values). To ascertain analytical accuracy, commercially available reference materials, with certified or recommended arsenic concentrations, were analyzed. In general, there was good agreement between obtained element concentrations in the reference materials used and the reference values (data available as Supporting Information), indicating good analytical quality. To compensate for variations in the dilution of urine, the measured concentrations were adjusted to the mean specific gravity (1.020 g/mL) measured by a digital refractometer (EUROMEX RD 712 clinical refractometer; EROMEX, Arnhem, Holland). We preferred adjustment by specific gravity to that by creatinine, the most commonly used adjustment method, because we have found that the excretion of creatinine varies markedly with age, muscle mass, physical activity, and meat 6876
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intake (14). Also, adjusting for density was a practical approach in the field.
Results In total 198 women participated in the study. They had a median age of 34 years (range 12-80), body weight of 57 kg (37-100), and BMI of 25 (16-40). The found concentrations of the measured 31 elements in drinking water are presented by village in Table 1. The most elevated concentrations were found for arsenic, lithium, cesium, rubidium, and boron. In addition, the concentration of vanadium was moderately elevated in some of the villages. Concentrations of other toxic metals such as cadmium, lead, beryllium, chromium, and uranium were low. None of the water samples contained significant amounts of essential trace elements and the concentrations of calcium, magnesium, iron, and manganese, which are often elevated in groundwater, were low. The concentrations in urine are presented for elements that were elevated in drinking water (Table 2). The interviews revealed that local tap water was the main source of drinking water. The women reported regular intake of meat, but no intake of fish or other seafood. Among the women in San Antonio de los Cobres there was a significant correlation of arsenic or lithium in urine with the number of glasses of water consumed per day (range one to more than three glasses), based on questionnaire data (for arsenic: rs ) 0.180, p ) 0.023; for lithium rs ) 0.173, p ) 0.029). Comparison of element concentrations (Li, B, V, As, Rb, Sr, Mo, Cs, U) in water samples, collected in San Antonio de los Cobres over several years for measurements of arsenic (7), showed fairly small temporal variations in the concentrations of all the measured elements (data available as Supporting Information).
Discussion This is the first study to show highly elevated combined exposure to arsenic, lithium, cesium, rubidium, and boron through drinking water. The study was performed in several villages and settlements in the Puna region in northern Argentina, where we previously have reported elevated concentrations of arsenic. In four of the six studied Puna villages the concentrations of arsenic and boron exceeded the maximum levels allowed by the Argentinean Alimentary Code, as well as the guideline values recommended by the WHO. Guideline values need to be established for lithium and cesium. The high-level exposure to arsenic, lithium, boron, and cesium was confirmed by elevated concentrations in urine, and the interviews with the study individuals and local health authorities confirmed that local tap water, derived
TABLE 1. Concentrations of Elements in Drinking Water in Different Puna Villages in the Salta Province, Northwestern Argentina guideline values
element
settlement close ICPMS gas San Antonio de to San Antonio de Sta Rosa de los modes los Cobres los Cobres Pastos Grandes useda N ) 2b N ) 1c N ) 1b
Salar de Pocitos N ) 2b
Tolar Argentinean Cobres Olacapato Grande Alimentary N ) 1 b N ) 2b N ) 1 b Code
Li µg/L Be µg/L B µg/L Mg mg/L Al µg/L Si mg/L P µg/L S mg/L
std std std He std He std He
1003; 1005
