Risk Analysis of Acute Or Chronic Exposure to Arsenic of the Inhabitants in a District of Buenos Aires, Argentina

Original scientific paper

Journal of Sustainable Development of Energy, Water and Environment Systems
Volume 4, Issue 3, September 2016, pp 234-241
DOI: https://doi.org/10.13044/j.sdewes.2016.04.0019
Cristina Vázquez, María C. Rodríguez Castro, Oscar Palacios, Susana P. Boeykens
Laboratorio de Química de Sistemas Heterogéneos, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850, C1063ACU-Buenos Aires, Argentina

Abstract

The arsenic occurrence in the water constitutes a serious world health concern due to its toxicity. Depending on the intensity and duration of exposure, this element can be acutely lethal or may have a wide range of health effects in humans and animals. In Argentina, the origin of arsenic is mainly natural, and related to different geological processes. The Argentinean concern about arsenic and its influence on human health dates back to the previous century. The disease ascribed to arsenic contamination was called ‘chronic regional endemic hydroarsenism’. It is produced by the consumption of water with high levels of this element. In our study, we focused in La Matanza district, a very populated site in the Buenos Aires Province. An increasing concern of the inhabitants of the area regarding health problems was detected. In order to establish a full view of arsenic exposure in the area, several matrices and targets were analyzed. As matrices, water and soil samples were analyzed. As targets, canine and human hair was studied. The aim of this study was to investigate acute and chronic exposure to arsenic of La Matanza inhabitants.

Keywords: Arsenic, Water contamination, Human hair, Canine hair, Chronic regional endemic hydroarsenism.

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INTRODUCTION

The environmental situation in the Buenos Aires Metropolitan Area is characterized by a marked deterioration of urban ecosystems. This deterioration in life quality is caused by non-controlled anthropogenic pollutant discharges. Surface water, groundwater as well as soils and sediments have been widely polluted by industrial and municipal wastewaters, household wastes, and agricultural activities over the past several decades. At the same time, due to population growth in urbanized areas, the risk of exposition to polluted waters through drinking water has grown [1].

La Matanza district, located in the Buenos Aires Province, with an area of 325.71 km2 and a population of 1,249,958 inhabitants is divided into 15 villages. Among them, Virrey del Pino, with an area of 116,520 km2 and a population of 90,382 inhabitants is located near the 3rd National Road. In our study, we focused the investigation in Los Alamos neighborhood which is affected by industrial activity in the area and a lack of monitoring. This vicinity is classified as residential, but lacks the most essential public services such as tap drinking water, natural gas and sewers. Population has to get water by particular pumping wells drilling from 14 to 40 m depth to reach the aquifer. There are no paved roads, complicating the access to the vicinity particularly in rainy days and aggravating the situation of urban hygiene [2].

A large area of Argentina is affected by chronic endemic regional hydroarsenism (HACRE, hidroarsenicismo crónico regional endémico, in Spanish). Symptoms and health problems for humans were densely studied by physicians and toxicologists. Cancer [3], [4], dermatitis [5] and Bowen disease [6] was associated to the presence of As in drinking water. La Matanza lies within this area. In this region, volcanic material is the principal component of loessic and eolic deposits causing a natural presence of arsenic in water as a product of different geological processes, what was studied in different regions of Argentina, like Córdoba [7], [8], La Pampa [9] and Santiago del Estero provinces [10]. Matanza population drink water exceeding the recommended 10 μgAsL−1 (WHO drinking water standard) [11].

Consuming such water for long periods of time can cause chronic contamination in people, implying a higher risk of skin [12], bladder [13], lung and kidney [14] cancers as was suggested by several authors.

For that reason it is important to bring new forms of monitoring of this element in the environment, being the biomonitoring an evaluation methodology which includes all absorption pathways and all sources of pollution.

Dog (Canis lupus familiaris) has long been an important research model and a promising tool as a target and bioindicator for metal contamination [15]-[17]. This is due to the fact that dogs share the same environment as humans [18] and, as mammals, have similar responses to pollutants [19].

Blood and hair particularly appear as interesting monitoring tools for arsenic exposure risk assessment [20], [21]. Horse [22], reindeer [23], cat and dog [24] hair has been studied by several authors as targets to assess the potential exposure of these animals to arsenic.

In order to establish a full view of arsenic exposure in the area, during this study several matrices and targets were analyzed. As matrices, water and soil samples were analyzed; as targets, canine and human hair samples were selected.

The aim of this study was to investigate acute and chronic exposure to arsenic among the Virrey del Pino inhabitants. The analytical techniques used in this study were selected by considering the available amount of sample, sensitivity, accuracy, reproducibility and detection limits of the method.

X-ray fluorescence spectrometry was used for the direct analysis of water samples and, after an in situ microwave digestion for dog hair and soil samples [25]. Hydride generation atomic absorption spectrometry was used for the analysis of human hair samples.

EXPERIMENTAL

Environmental issues were assessed after the first visit to the district on the 20th February 2012. This inspection defined a preliminary sampling plan based on the observation at a glance of pollution sources and informal interviews with neighbors concerning its health status. With this information, a sampling plan which included sampling of drinking water and soil as well as human and dog hair was developed.

The criterion for the final sampling was determined by designing a grid about 10 by 10 blocks on either side of Route 3, 44.5 km. The sampling was random class, defining 24 houses along the Chacon stream, tributary of the La Matanza river. All points were recorded using a Geographic Positioning System (GPS). Water samples were collected in each of the 24 houses. A volume of 1,000 mL, previously filtered through a 0.45 Millipore, were placed in Nalgene bottles, previously treated with 10% nitric acid for 48 h, washed with distilled water and then with deionized water, two or three times. The samples were acidified with concentrated HNO3 (1 mL per bottle) and transported and stored under refrigeration (4 °C) until analysis.

Soil and sedimented dust nearby Los Alamos samples were obtained with plastic shovels. Each portion of 500 g was taken and ground again using tungsten carbide mortars in a Shatter box mill. This sub-sample was sieved through a nylon sieve of 60 μm were left. A portion of 10 g was weighted and pressed in a hydraulic (press 17 tons cm−2) without any binder obtaining pellets (30 mm diameter) for EDXRF measurement. The standard reference materials SRM 270 San Joaquin Soil and SRM 2710 Montana Soil Highly Elevated Traces were used for calibration curve. The IAEA Soil 7 and GBW07405 (China National Publishing Trading Corporation) were employed for validation.

Canine hair samples were obtained from dogs located within 100 meters around a metal factory located in the neighborhood of Los Alamos. All of the sampled dogs were clinically healthy and under normal food regime as reported by the owners. A survey was completed by the owners for each dog in their household during the sample collection procedure. The survey provided information on breed, age, gender, time of residence in the house, type of surface in the home yard (e.g. grass, cement), hours spent outdoors, and use of pesticides, medications or oral supplements that might affect hair arsenic levels. Inhabitants of the houses provided human hair. Freshly cut human scalp hair samples were collected from 18 individuals, male and female, aged between 7 to 35 years. The samples were quickly put in a pre-code polyethylene bag and sealed. 0.1 g of hair was weighted and put into a beaker with 5 mL of concentrated HNO3. The beaker was placed on a hot plate, adjusting heating to a gentle boil record. Then 0.5 mL of 30% H2O2 was added. Finally the digested sample was transferred to an aphorized 1.00 mL Eppendorf tube. Total arsenic concentration was measured by TXRF previous adding Co internal standard.

RESULTS AND DISCUSSION

Water samples were analyzed by TXRF. In addition to As, the analysis also allowed the determination of other elements such as P, K, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Br, Sr and Pb, as presented in Table 1.

TXRF results of drinking water samples

Sample

Ca

K

V

Cr

Mn

Fe

Cu

Zn

As

Sr

[mgL−1]

[μgL−1]

1

33

9.8

<5.0

<5.0

125

41

85

18

37

690

2

10

23.0

15

10

55

100

55

50

64

890

3

21

7.3

25

9

45

85

65

64

49

450

4

32

7.8

10

8

44

45

45

45

55

680

5

13

7.9

25

8

40

66

55

60

48

770

6

34

12.0

23

10

25

45

85

85

59

660

7

55

13.0

15

<5.0

23

98

74

75

59

1,000

8

26

8.0

12

<5.0

10

88

63

85

58

890

9

59

8.2

20

<5.0

15

45

46

45

49

560

10

29

7.4

<5

<5.0

12

99

40

56

67

780

11

31

8.2

20

<5.0

30

120

32

55

70

690

12

19

11.2

10

8

20

110

54

110

63

890

13

33

12.1

25

<5.0

21

80

45

80

59

450

14

16

10.0

23

<5.0

15

90

55

70

59

680

15

21

9.8

15

<5.0

11

100

40

60

58

700

16

32

7.6

25

<5.0

15

80

33

65

49

450

17

13

7.8

30

8

16

70

50

78

67

660

18

30

8.9

20

<5.0

20

80

45

80

76

890

19

55

7.2

20

<5.0

32

90

40

60

63

780

20

26

15.0

16

10

41

110

33

85

59

560

21

60

24.0

20

<5.0

40

120

45

74

58

800

22

29

14.0

<5

<5.0

30

110

33

56

49

700

23

32

13.6

<5

10

20

105

52

85

67

650

24

40

11.8

10

<5.0

33

100

40

60

70

850

Copper, strontium, iron and zinc distributions show higher concentration values than the average of their limits of quantification. Chromium, manganese and vanadium show a greater accumulation of class frequencies near their limits of quantification. It should be noted that the use of TXRF allows detection level concentrations in the order of μgL−1. This condition is mandatory to assess the contamination of natural groundwater and the effectiveness of applied treatment strategies. The level of arsenic in all water samples is higher than permitted by Argentine Food Code values (10 μgL−1 by Argentinean National Law N°18284) (Table 2). This is a factual data that the study area is within the affected chronic regional endemic hydroarsenism zone. This pathology, typical of regions with high concentrations of As in the water, affecting large areas of the provinces of Argentina: Buenos Aires, Chaco, Salta, Santiago del Estero, Santa Fe, La Pampa, further comprising the entire province of Cordoba. However, in the soil samples studied (Table 3), no large quantities of As were found (compared with those found in contaminated soils [7]), which indicates that this element is present in the rocks that water must cross to reach the aquifer but not in the land of the surface soils.

Detection Limits (DL), Maximum Measured Value (MMV), minimum Measured Value (mMV) and Maximum Guidelines Value (MGV) for the studied analytes (μgL−1) in water samples

Element

DL

MMV

mMV

MGV

[μgL−1]

K

7

60

26

-

Ca

10

24

11

400a (as CaCO3)

V

5

30

<5

100b

Cr

5

10

8

50a

Mn

5

125

11

100a

Fe

5

120

45

300a

Cu

6

85

32

1,000a

Zn

2

110

18

5,000a

As

5

76

37

10a

Sr

30

1,000

450

4,000b

aArgentinean National Law 18284 - Argentinean Food Code

bUS Environmental Protection Agency

EDXRF results from soil samples

Sample

Ca

Fe

Ti

Cr

Mn

Ni

Cu

Zn

Sr

Zr

Pb

As

[%]

[mgL−1]

1

0.55

3

0.47

20

1,036

34

10

136

210

690

30

>5

2

1.30

3

0.45

20

898

32

10

180

200

590

40

10

3

0.94

3

0.44

20

742

28

10

207

190

540

50

>5

4

0.93

3

0.41

20

638

28

10

167

180

590

35

14

5

1.60

3

0.42

31

1,118

25

28

122

190

540

35

>5

6

1.40

4

0.41

21

756

29

10

221

200

500

38

>5

7

1.40

4

0.40

40

857

31

301

564

190

470

40

>5

8

1.20

4

0.43

37

875

25

11

112

180

520

45

9

9

0.93

4

0.43

29

826

31

16

237

170

540

48

>5

10

0.70

3

0.47

23

970

35

10

147

200

700

49

>5

11

0.53

4

0.47

37

1,075

27

10

137

210

380

55

25

12

1.20

3

0.39

132

925

26

10

266

220

410

58

>5

13

1.80

3

0.36

104

672

25

19

286

190

350

59

>5

14

0.98

3

0.45

23

789

35

15

284

200

480

56

18

15

1.40

3

0.42

150

725

32

11

189

210

490

56

>5

16

0.79

3

0.46

20

710

29

10

121

200

580

58

>5

17

1.40

3

0.46

27

666

28

10

118

210

530

57

>5

18

1.27

4.60

0.47

20

888

27

10

92

220

420

20

17

19

0.34

4.30

0.55

132

932

41

15

156

230

330

50

25

20

1.20

4.50

1.10

140

500

50

30

100

200

350

70

14

21

1.00

5.60

0.80

90

1,200

80

30

200

300

600

20

>5

22

1.00

6.00

0.90

80

1,300

60

20

230

320

860

50

8

23

1.00

6.10

0.70

60

150

80

25

150

230

960

60

>5

24

1.50

5.00

0.60

60

600

90

30

120

260

860

30

7

The average concentrations found in the hair of the studied dogs was 24 ± 2 mg gDW−1, that is significantly higher than the concentration measured in controls (1.0 ± 0.4 mg gDW−1; p<0.001). According to the US Department of Health and Human Services, arsenic levels above 1.00 mg gDW−1 represent excessive exposure, so the dogs sampled appear to be contaminated by chronic exposure.

In human hair samples, normal level of arsenic was detected evidencing non chronical contamination.

Pb and Cr were found in sedimented dust from the smelter nearby Los Alamos (Table 4). Dust pollution can be exposed and being in contact with human’s body in various ways besides through inhalation. Therefore, continuous accumulation of pollutants in the neighborhood streets can lead to chronic contamination of the inhabitants with other metals.

Metal concentrations found in sedimented dust from smelter in Los Alamos and in Buenos Aires

Los Alamos

Buenos Aires (control)

Pb in sedimented dust from smelter [mgkg-1]

356

soil mean: 10

Cr in sedimented dust from smelter [mgkg-1]

136

soil mean: 48

CONCLUSIONS

During this study, water and soil samples were analyzed as matrices and canine and human hair samples were selected as targets to investigate acute and chronic exposure to arsenic at the Los Alamos neighborhood in Virrey del Pino, La Matanza, Buenos Aires, Argentina.

The results of the present study provide evidence of arsenic contamination at Los Alamos neighborhood; probably it is due to the use of groundwater for drinking and cooking. Chronic accumulation of arsenic in dogs was found. These results serve as an alert for local population concerning arsenic exposure risks. This work is a preliminary test about the use of canine hair as sentinel of arsenic exposure. The goal of this research was to demonstrate that monitoring other matrices and targets can be achieved in a simple and economically way using TXRF technique. Such a monitoring is needed either to check this analyte in soils and water as well as in hair and dust bringing a complete panorama of the risk of this element for leaving organism.

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