Expo Health DOI 10.1007/s12403-017-0257-7
ORIGINAL PAPER
Arsenic Level and Risk Assessment of Groundwater in Vehari, Punjab Province, Pakistan Muhammad Shahid1 · Muhammad Khalid1 · Camille Dumat2 · Sana Khalid1 · Nabeel Khan Niazi3,4,5 · Muhammad Imran1 · Irshad Bibi3,4 · Iftikhar Ahmad1 · Hafiz Mohkum Hammad1 · Riaz Ahmad Tabassum1
Received: 28 March 2017 / Revised: 27 September 2017 / Accepted: 30 September 2017 © Springer Science+Business Media B.V. 2017
Abstract Arsenic (As) contamination in different areas of the world has been reported, which poses serious health threats to humans by its different routes of exposure. There exists comparatively rare data regarding arsenic level in groundwater of Punjab, Pakistan, which is normally used for drinking purpose. Therefore, the present study was planned to assess the contamination of arsenic in the drinking water of district Vehari in Punjab, Pakistan. A total of 156 drinking water samples were taken from different previously unexplored (rural and urban) areas. Various groundwater sources (electric pump, hand pump, and tube well) were targeted at different depths (50–350 ft) of the three tehsils (Burewala, Vehari, Mailsi) of district Vehari. Drinking water samples were subjected to measurement of the arsenic level, as well as other parameters of water were also checked including pH, electrical conductivity, chloride, cations, carbonates, and bicarbonates. It was found that 95% of groundwater samples were unfit for drinking purpose, because some areas of district Vehari were found with arsenic levels higher than World Health Organization (WHO) safe limit of As * Muhammad Shahid
[email protected] 1
Department of Environmental Sciences, COMSATS Institute of Information Technology, 61100 Vehari, Pakistan
2
Centre d’Etude et de Recherche Travail Organisation Pouvoir (CERTOP), UMR5044, Université J. Jaurès - Toulouse II, 5 allée Antonio Machado, 31058 Toulouse Cedex 9, France
3
Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, 38040 Faisalabad, Pakistan
4
MARUM and Department of Geosciences, University of Bremen, 28359 Bremen, Germany
5
Southern Cross GeoScience, Southern Cross University, Lismore 2480, NSW, Australia
(10 μg/L) in drinking water. Arsenic-induced health risks were also estimated with respect to average daily dose, hazard quotient, and carcinogenic risk for the people who were relying on arsenic-rich groundwater for drinking purpose. It is found that the people of district Vehari are at the serious carcinogenic health risk. This study highlights that urgent management and monitoring measures are imperative for the people in the study area, in order to minimize the arsenicmediated health effects, as well as to develop effective remediation strategies for arsenic-contaminated drinking water. Keywords Arsenic · Contamination · Groundwater · Health risk · Vehari
Introduction Arsenic has gained a substantial attention in recent years owing to its high concentration currently observed in drinking water and as such its adverse impacts on human health (Gunduz et al. 2017; Rafiq et al. 2017a, b; Zeng et al. 2017). Contamination of groundwater (drinking water) by As is a potentially serious human health dilemma (Shakoor et al. 2016; Gunduz et al. 2017; Niazi et al. 2017a, b). The toxicities of various As compounds to man, animals, and plants have been studied by various researchers (Gunduz et al. 2017; Shahid et al. 2017). Taking into account the potential toxicity of As and its compounds, the US-EPA, World Health Organization (WHO 2011), and Food and Drug Administration (FDA) have set a drinking water limit of As at 10 µg/L. In 2006, the Department of Environmental Protection for New Jersey set As standard for drinking water at 5 µg/L. Arsenic is pervasive in the environment and occurs in soil, water, atmosphere, and the living organisms (Mehmood
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et al. 2017; Niazi et al. 2017a, b; Rafiq et al. 2017a, b). Arsenic is the natural component of more than 200 minerals worldwide (Bissen and Frimmel 2003). Desorption and dissolution of these As-containing minerals are generally recognized as the major source of As contamination of groundwater (Bissen and Frimmel 2003; Shakoor et al. 2015). Natural processes redistribute significant amount of As (ranging from 50 to 3000 mg/L) every year from the contaminated aquifers to drinking water (Ali and Tarafdar 2003). Anthropogenic sources of As also release substantial quantities of As into the aquatic environment. Major anthropogenic sources of As include mining activities, smelting, combustion, agrochemicals, wood treatment, paints, cosmetics, and dyes etc. (Mohan and Pittman 2007). Water is the main pathway of As entrance to human body (Khalid et al. 2017a, b). Contamination of drinking water by As has been observed in many countries around the world especially in South Asia (Shakoor et al. 2015; Alam et al. 2016; Hoover et al. 2017; Zeng et al. 2017). Arsenic-contaminated groundwater is used as drinking water for millions of people in China, India, Bangladesh, Pakistan, USA, Taiwan, Vietnam, and Chile (Malik et al. 2009; Mondal et al. 2013). Arsenic contamination of groundwater has also been reported in Minnesota, Spain, North Mexico, Canada, Japan, Poland, Argentina, New Zealand, and Hungary (Mondal et al. 2013; Shakoor et al. 2016). Hence, contamination of groundwater has received significant attention from researchers and policy makers worldwide in the recent years (Niazi et al. 2011; Mondal et al. 2013; Niazi and Burton 2016). It is reported that approximately 70% of groundwater and surface water reserves in Pakistan have been contaminated by organic, inorganic, and biological contaminants (Azizullah et al. 2011; Khalid et al. 2017a, b). Recent studies showed As contamination of groundwater in Punjab and Sindh province of Pakistan (Malik et al. 2009; Shakoor et al. 2015). Recently, researchers discovered As contamination in the wells of Pakistan with As levels above the recommended values in drinking water (10 µg/L by US-EPA 2005 and WHO 2011). Kazi et al. (2009) reported that 61–73% population in Sindh province of Pakistan was suffering from chronic As toxicity. In addition to Sindh province, the groundwater of southern Punjab is also reported to contain high levels of As (up to 201 µg/L) (Shakoor et al. 2015). There is a possibility that numerous people in the country use As-contaminated water for drinking and are at high risk of health complications. Recently, the food security and health risk assessment have gained considerable attention worldwide (Mombo et al. 2016; Xiong et al. 2016). Using As-contaminated groundwater for drinking purpose is harmful to human health. Hence, information of health risk of As from drinking water will be of great help to ensure the basic safety of
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drinking water for ever-rising population. It is crucial to evaluate the potential health risks which could be linked with the use of As-contaminated drinking water. Arsenic level in drinking water/groundwater is used to estimate the potential health risk such as hazard quotient (HQ), average daily dose (ADD), and carcinogenic risk (CR). Several previous studies used these parameters to evaluate the potential toxicity of contaminated drinking water (Mondal et al. 2013; Li et al. 2014; Wu and Sun 2016; Zeng et al. 2017). For example, Muhammad et al. (2010) evaluated health risk assessment of As in Khyber Pakhtunkhwa province of Pakistan and reported that HQ values > 1 in the study area. Similarly, Sultana et al. (2014) reported that > 85% drinking water samples in Lahore had HQ values > 1 (HQ = 2.3–48.6) in PunjabPakistan. Keeping in view the acute and chronic toxicity of As and possible contamination of groundwater, the current study is planned to analyze As level in different types of groundwater (electric pump water, tube well water, turbine water etc.) used for drinking purpose in three tehsils (Burewala, Mailsi, and Vehari) of Vehari district, Punjab, Pakistan.
Materials and Methods Study Area Vehari is a city of Multan Division in Punjab Province, Pakistan. The city is located between Rivers Sutlej and Ravi. It is situated between 30°04′19″N and 72°35′28″E points at an altitude of 446 ft (135 m). District Vehari has a total population of 7,000,000. The climate of Vehari is severe with very hot summer (April–August, up to 50 °C) and very cold winter (November–January, up to 1 °C). The average annual rainfall in Vehari is about 127 mm, which pours mainly during monsoon season (July and August). Dust storms occur commonly during summer. The aquifer of Punjab province is generally originated from unconsolidated alluvial sediments with different compositions of sand, silt, and clay. Mineral analyses have indicated the presence of quartz, muscovite, and some percentage of heavy minerals (Ahmad et al. 2002). The sedimentary complex is about 400 meters thick and has been developed by the tributaries of the Indus River during Pleistocene–Recent age. Regardless of varied composition of alluvial complex, groundwater in Punjab occurs under water-table conditions. The electric pumps and tube wells pump the deep groundwater from the depth of 75–200 m. The rivers (Chenab, Satluj, Ravi, Sindh, and Jhelum) and the canals passing through the area are possible sources of aquifer recharge.
Arsenic Level and Risk Assessment of Groundwater in Vehari, Punjab Province, Pakistan Table 1 Number of groundwater samples collected from three tehsils of Vehari district Study area
Rural
Urban
Total
Burewala tehsil Mailsi tehsil Vehari tehsil Vehari district
41 23 56 120
9 16 11 36
50 39 67 156
by Estefan et al. (2013). A 25 ml of water sample was taken for As determination. Concentration was measured using a hydride generation atomic absorption spectrometer (HGAAS, Agilent AA240 with VGA 77). A standard reference (non-contaminated water sample) was used for quality assurance. In addition, As readings were replicated twice for each sample by HG-AAS. Human Health Risk Assessment
Table 2 Groundwater samples collected from different sources of three tehsils of Vehari district Study area
E.P.
H.P.
Tube well
Total
Burewala tehsil Mailsi tehsil Vehari tehsil Vehari district
26 14 35 75
17 22 25 64
7 3 7 17
50 39 67 156
E.P. electric pump, H.P. hand pump
Groundwater Sampling The study area of Vehari district was divided into three parts based on three tehsils of Vehari (Mailsi, Vehari, and Burewala). Total 156 groundwater samples were collected from three tehsils of Vehari district. These samples were collected from rural (120) and urban (36) areas (Table 1). Groundwater samples were collected from hand pumps (64), electric pumps (75), and tube wells (17) at various depths (50–400 ft) (Table 2). All pumps/wells were flushed for at least 5 min to obtain fresh water prior to collecting groundwater samples which is known as purging. Groundwater samples (1000 mL each) were taken in duplicate in two separate plastic bottles having airtight caps. One water sample was acidified on-site by adding 2–3 drops of concentrated nitric acid (HNO3) to stabilize As and metal ions and reduce their precipitation (Khan et al. 2013). The acidified water samples were used to analyze total As contents and other elements. The second water sample was kept non-acidified to analyze various cations and anions. Groundwater Analysis Groundwater samples were analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), magnesium (Mg), sodium (Na), potassium (K), calcium (Ca), carbonates (CO3), bicarbonates (HCO3), chloride (Cl), sulfate (SO4), and As following standard methods. Then Na, K, and Ca were determined in drinking water samples using flame photometer (Richards 1954). Arsenic contents in water samples were measured following the protocol described
Exposure Assessment The human health risk assessment model derived by the USEPA was used to evaluate the toxic effects of As present in drinking water on the health of people in three study locations (US-EPA 2005). The health risk assessment was done to estimate the probability of individuals being exposed to As poisoning from drinking water. For this purpose, average daily dose (ADD) of As due to the intake of As-contaminated drinking water was calculated by the following equation (Li et al. 2016):
ADD =
C × IR × ED × EF , BW × AT
where C represents the concentration of As in water (mg/L), IR is the water ingestion rate (L day−1), ED abbreviates exposure duration (assumed 67 years to make a comparison with previous studies from Pakistan and other countries), EF indicates exposure frequency (365 days year−1), BW is the body weight (72 kg) (Sultana et al. 2014), and AT means average life time (24,455 days). Chronic and Carcinogenic Risk Assessment Chronic and carcinogenic risk levels were also determined in individuals of the study area. The hazard quotient (HQ) was computed from ADD by the following equation (USEPA 2005):
HQ =
ADD Rfd
w h e r e R f D r e p r e s e n t s o r a l r e fe r e n c e d o s e (0.0003 mg kg−1 day−1) for As calculated by US-EPA (USEPA 2005). Cancer risk (CR) was calculated using the following equation:
CR =
ADD CSF
where CSF is the cancer slope factor for As which is 1.5 mg kg−1 day−1, according to US-EPA model (US-EPA 2005).
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Statistical Analysis
Table 3 Physico-chemical parameters of groundwater of district Vehari
Statistical analysis of data was carried out using the Statistical Package for the Social Sciences (SPSS Statistics, Ver 20). Mean values with different alphabets represent a significant difference (p Vehari > Burewala. Maximum concentration of As in the urban areas of Mailsi groundwater was 130 µg/L with mean concentration of 49.6 µg/L. Similarly, in urban areas of two tehsils mean concentrations of As were 28 and 47.9 µg/L, respectively, for Burewala and Vehari. In rural areas, As level was higher in the groundwater of Vehari compared to Mailsi and Burewala. Mean concentrations were 40.2, 28.8, and 39.6 µg/L, respectively, for rural areas of Vehari, Burewala, and Mailsi. Maximum concentration of 132 µg/L was found in the groundwater of Mailsi collected from rural areas. Arsenic Level in Groundwater Collected from Different Sources Figure 1c shows As concentrations in groundwater collected from different sources such as electric pump, hand pump, and tube well. Water samples taken from tube wells and electric pumps showed almost same mean As level: 48.5
and 48.2 µg/L, respectively. However, water samples taken from hand pumps showed significantly lower mean As level (27.2 µg/L) compared to tube wells and electric pumps water. Arsenic Level in Groundwater Collected at Different Depths Arsenic concentrations in the groundwater of district Vehari collected from different depths 0–100, 100–200, 200–300, and > 300 ft are given in Fig. 1d. With increasing depth (from 0–100 to 200–300), mean concentration of As in groundwater also increased from 32.5 to 61.5 µg/L, whereas for depth > 300 ft, As concentration decreased to 50.5 µg/L. This showed that aquifer of Earth’s crust in Vehari at a depth of 200–300 ft is generally more contaminated with As compared to upper and lower aquifers. Exposure Assessment and Cancer Risk Assessment Table 5 shows the health risk assessment of As with respect to ADD, HQ, and CR for the people who are using Asrich groundwater for drinking purpose in Vehari district. In this study, ADD ranged from 0.01 to 4.6 µg kg−1 day−1 with a mean concentration of 1.3 µg kg−1 day−1. The mean ADD value was higher in urban areas (1.5 µg kg−1 day−1) of Vehari district compared to rural areas (1.3 µg kg−1 day−1). At tehsil level, ADD value of As was higher for Mailsi (1.5 µg kg−1 day−1) than Vehari (1.4 µg kg−1 day−1) and Burewala (1.0 µg kg−1 day−1). Similar to Vehari district, mean ADD value was higher for urban areas compared to rural areas in all the three tehsils. In this study, mean value of HQ was 43 for Vehari district with a minimum and maximum values of 0.5 and 153, respectively. The HQ value was observed higher in urban areas both at district and tehsil levels compared to rural areas. Three tehsils showed mean HQ value in decreasing order of Mailsi (50) > Vehari (47) > Burewala (33). The potential CR values of Vehari district spanned 0.00001–0.00306 in study area. Similar to ADD and HQ, CR values were higher in urban areas both at district and tehsil level compared to rural areas. Moreover, groundwater of tehsil Mailsi showed more carcinogenic risk than the water of Vehari and Burewala.
Discussion Physico‑Chemical Parameters of Groundwater of District Vehari Food and water safety has received considerable attention during the last few decades owing to numerous toxic
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Fig. 1 Arsenic levels (µg/L) in groundwater of a Vehari district, b urban and rural areas, c from different sources, and d from different depth
effects of contaminated water and food on human health. Drinking water that contains high levels (above threshold values) of certain ions can cause health hazards. Quality of groundwater used for drinking purpose is an important factor determining its effects on human health. The “Criteria and Guidelines for Quality Drinking-Water” published by World Health Organization (WHO 2011) have been used worldwide. Many countries around the world have developed/adopted criteria and guidelines based on WHO recommendations. In this study, quality of drinking water has been evaluated using WHO guidelines with respect to the following parameters: pH, EC, TDS, hardness, Na, K, Ca, CO3, Cl, and As. The range of pH suitable for drinking purpose is considered to be 5.0–9.0, although 6.5–8.5 is preferable (PCRWR 2016). In this study, the pH of all groundwater samples collected from urban and rural areas of Vehari district were within the range of permissible limit (6.5–8.5) given by WHO (2011) criteria. However, data from the current study showed that groundwater of Vehari district was slightly alkaline (mean pH 7.8).
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The groundwater of Vehari district showed high EC (5205 µS/cm) which was 160% higher than the WHO (2011) permissible limit (2000 µS/cm). Iqbal et al. (2014) also observed higher EC of 2300 µS/cm in the groundwater of Kohat City, Pakistan. All the values of TDS in urban and rural areas of Vehari district exceeded the permissible limit of the Pakistan Standards and Quality Control Authority (PSQCA) (100–500 mg/L). Maximum concentration of TDS in the groundwater of Vehari district was twelve times higher than the maximum allowable limit. High concentration of soluble salts in groundwater of Vehari district can be due to the dissolution of various minerals such as siderite (FeCO3), aragonite [CaCO3], calcite [CaCO3], and dolomite [CaMg(CO3)2] from bed rocks and indigenous soil (Shakoor et al. 2015). A study carried out by Naeem et al. (2007) in Lahore found that about 10–20% of samples in the study area crossed maximum permissible limit for TDS. The results obtained from this study showed that groundwater samples contained 303, 500, −68%, 66% higher Ca, Na, Mg, and K levels, respectively, when compared with the
Arsenic Level and Risk Assessment of Groundwater in Vehari, Punjab Province, Pakistan Table 5 Average daily dose, hazard quotient, and carcinogenic risk of As in Vehari district Parameters
District
Tehsils
Vehari
Burewala
Average daily dose (ADD) Mean 1.30 Median 0.94 Minimum 0.01 Maximum 4.58 SD 1.00 Hazard quotient (HQ) Mean 43.4 Median 31.4 Minimum 0.5 Maximum 152.8 SD 33.3 Carcinogenic risk (CR) Mean 0.00087 Median 0.00063 Minimum 0.00001 Maximum 0.00306 SD 0.00067
1.00 0.70 0.02 4.27 0.86 33.5 23.3 0.8 142.5 28.8 0.00067 0.00047 0.00002 0.00285 0.00058
Vehari
Mailsi
1.41 1.04 0.01 4.30 0.99
1.51 1.07 0.37 4.58 1.11
46.9 34.8 0.5 143.3 33.0 0.00094 0.00070 0.00001 0.00287 0.00066
50.2 35.8 12.3 152.8 37.0 0.00100 0.00072 0.00025 0.00306 0.00074
guideline values of Pak-EPA recommended for these elements. Maximum concentration of cations was found in the groundwater of urban areas of Vehari district compared to rural areas. Findings of the present study are similar to those conducted by Chaudhary (2005) who reported Na 33–360, K 30–165, and Mg 31–97 mg/L in Faridabad, an industrial town of Haryana-India. Desirable limit of C l− according to the WHO (2011) is specified as 1000 mg/L (31 mg/L). All natural types of water can contain C l−. High concentration of C l− is due to invasion of domestic wastes and the disposals by the human activities
(Jha and Verma 2000). Maximum Cl− of 62 mg/L was found in district Vehari which is two-fold higher than the WHO limit (31 mg/L). Maximum concentrations of C l− in all samples were higher than WHO limit. Similar results were found in drinking water of Kohat with Cl− concentration of 766 mg/L (Iqbal et al. 2014). Arsenic Level of Groundwater Arsenic is naturally occurring metalloid. Mineral deposits contain high As level in many areas which is dissolved by groundwater and hence contributes to groundwater contamination with As (Shakoor et al. 2016). Some recent studies showed an extremely higher As level in different areas of Pakistan (Shakoor et al. 2016). In this study, high level of As (mean 37.3 µg/L, median 27 µg/L, and maximum 132 µg/L) has been recorded in 156 samples collected from three tehsils (Burewala, Vehari, and Mailsi) of Vehari district (Fig. 1a). Arsenic concentration in 95% (148 out of 156) of groundwater samples collected from Vehari district was above WHO (2011) permissible limit (10 µg/L) (Fig. 2). Two samples from each of Burewala and Mailsi tehsils while four samples from Vehari tehsil contained As level 100 µg/L (Fig. 2). Mailsi tehsil showed greater mean As concentration (42.4 µg/L) compared to Vehari (40.8 µg/L) and Burewala (28.7 µg/L). The IDW interpolation of the As data (Fig. 3) of groundwater samples showed that there is a possible threat of As-induced toxicity from groundwater which is used for drinking purpose in Vehari district. Long-term use of groundwater containing moderate or high levels of As can cause As accumulation in human body and may result in severe toxicity.
Fig. 2 Map showing sampling locations with arsenic level (µg/L) in groundwater of Vehari district
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Fig. 3 Inverse Distance Weighted (IDW) interpolation of the arsenic data in Vehari district
Arsenic contamination of groundwater has been reported in almost 105 countries worldwide with an estimation of exposed population of > 200 million worldwide at the concentration > 10 µg/L (Shakoor et al. 2016). Asian countries, especially the Ganga–Meghna–Brahmaputra (GMB) plain of Bangladesh and India contain the maximum As concentration (Chakraborti et al. 2010). People living in Bangladesh and some states in India (such as Bengal) have been exposed to the worst As poisoning of the century due to the use of As-contaminated groundwater for cooking, drinking, and crop irrigation (Shakoor et al. 2016). It is reported that the groundwater of 59 out of 64 districts in Bangladesh contains As level above safe limit set by WHO (10 µg/L) (Chakraborti et al. 2010). Arsenic concentration in groundwater is as high as 4730 and 3700 µg/L, respectively, in Noakhali (Bangladesh) and South Parganas (India) (Brammer and Ravenscroft 2009; Chakraborti et al. 2010). Shrestha et al. (2003) reported As concentration as high as 2620 μg/L in drinking water of Nepal. It is reported that approximately 80 million habitants in Bangladesh and almost 43 million people in India (West Bengal) rely on groundwater containing As concentrations several folds higher than WHO standard (Shakoor et al. 2016). The issue of groundwater contamination by As in Pakistan remained unobserved until a joint project conducted in 2000 by the United Nations Children Fund and Pakistan Council of Research in Water Resources. Results obtained from this project reported that As contamination of groundwater exceeded the WHO (2011) standard in several cities of Pakistan. The situation of groundwater contamination by As is very severe in Multan (Punjab), Ganbat, and Dadu (Sindh) where > 50% of the wells exceed the safe limit of 10 µg/L. In Pakistan, it is proposed that groundwater contamination by As is the result
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of natural (oxidation of As-rich minerals) and anthropogenic sources (use of fertilizers) (Shahid et al. 2015; Shakoor et al. 2015). Nickson et al. (2005) revealed that the highest As concentration was 906 µg/L in Muzaffargarh district (southern Punjab) of Pakistan. Recently, researchers discovered As contamination in the wells of Pakistan with As levels above the recommended US-EPA As level of 10 µg/L. Kazi et al. (2009) reported that 61–73% population in Sindh province of Pakistan was suffering from chronic As toxicity. Fatmi et al. (2009) reported clinical and epidemiological evidence of As skin lesions due to the use of As-contaminated groundwater for drinking in Pakistan. In addition to Sindh province, the groundwater of southern Punjab is also reported to contain high levels of As (Shakoor et al. 2015). Comparison of As concentration in groundwater samples with respect to depth showed that mean As level increased up to the depth of 300 ft and then decreased. This showed that groundwater 300 ft). However, at a depth of more than 100 m, they reported As free groundwater. International Atomic Energy Agency (IAEA) also reported high As level in shallow groundwater (at depths less than 70 m) in Bangladesh. The government of Bangladesh has installed about 10 million shallow (
