Arsenic contamination in Southern Punjab is evaluated in light of the drinking water guidelines of WHO & PSQCA. A brief resume of WHO guidelines development is given as under;

WHO has had a public position on Arsenic in drinking water since 1958.

1. The first version of international standards for drinking water of 1958 included arsenic in the category of toxic substances which if present in drinking water supplies at concentration above certain levels may give rise to acute danger to health and established 0.20 mg/l (ppm) as an allowable concentration (WHO, 1958).

2. The updated standards in 1963 kept arsenic in the same category however lowered the concentration to 0.05 mg/l.

3. An update in 1971, kept arsenic in the toxic substances category and reaffirmed the value of 0.05 mg/l.

4. The WHO guidelines for drinking water quality in 1984 recommended 0.05 mg/l as a guideline value with the explanation that based on available human health data that a concentration of 0.05 mg/l of arsenic in drinking water is not associated with any adverse health effects.

5. The last addition of WHO guidelines for drinking water (1993) established 0.01 mg/l (10 ppb) as a provisional guideline value for arsenic in drinking water.

6. Recommended limit of Pakistan Standards Quality Control Authority (PSQCA) for arsenic in drinking water is 50 ppb.

The collected analytical data is grouped into two main categories based on WHO guidelines and PSQCA standards for arsenic in drinking water. These are:

1. Category-A:      Water samples giving arsenic concentration above 10 ppb.

2. Category-B:      Water samples giving arsenic concentration above 50 ppb.

4.1.1 Arsenic in Bahawalpur District

In total 750 water samples were collected from all the 5 tehsils of Bahawalpur. About 18% water samples were found to be unsafe due to high arsenic concentration in Bahawalpur District of 10 ppb (WHO guidelines), however 2.63% can be declared as unfit if we follow PSQCA standard in Bahawalpur District are given in the Table-2. The tehsil-wise details of arsenic contamination can be seen in Table-2.

Table-2 Arsenic in Ground Water (Bahawalpur)

One hundred and fourty five samples were collected in Bahawalpur Tehsil from 18 union councils. Only 4.13 % samples were found above the threshold value of PSQCA. One hundred and ten samples were collected from 13 Union Councils of Tehsil Hasilpur. Only 9 samples (8.18 %) were found contaminated with arsenic having concentration more than 10 ppb. Seven samples (5.55 %) in Tehsil Khairpur had arsenic concentration more than 10 ppb and only one sample (0.92 %) had arsenic concentration more than 50 ppb (Table-2).

Incase of Tehsil Ahmedpur East, out of 185 water samples, 44 samples (23.78 %) exceeded the 10 ppb and 5 samples (2.70 %) had arsenic concentration more than 50 ppb. Whereas, 44 samples (20.95 %) out of 210 collected from 17 Union Councils of Tehsil Yazman had arsenic concentration beyond 10 ppb and 8 samples (3.80 %) falling in the range above 50 ppb. Tehsil Khairpur has lowest number of water samples, falling in the category with arsenic concentration above 10 ppb whereas in Tehsil Bahawalpur maximum numbers of water samples were found contaminated (Figure-4).

Fig.-4: %age of Samples > 10ppb (Bahawalpur District)

On the other hand Tehsil Hasilpur did not have any sample with arsenic concentration above 50 ppb whereas highest number of samples were found in Tehsil Bahawalpur which crossed the limit of 50 ppb (Figure-5). The overall results of District Bahawalpur showed that 18.33 % samples were found unsafe when compared with 10 ppb limit of WHO whereas 2.63 % samples out of 758 were found contaminated, if we consider PSQCA standards of 50 ppb. Only 14 (1.84 %) samples in Bahawalpur District fell in the range of 50-100 ppb, whereas 6 samples (0.79 %) exceed 100 ppb (Table-3 & 4).

Fig.-5: Arsenic in Ground Water Samples > 50 ppb (Bahawalpur District)

Table-3 Ground Water Samples of Bahawalpur District Having Arsenic (50-100 ppb)

Table-4 Ground Water Samples of Bahawalpur District Having Arsenic Above 100 ppb

4.1.2 Arsenic in Rahim Yar Khan District

Rahim Yar Khan District has four teshils namely Sadiqabad, Rahim Yar Khan, Khanpur and Liaqatpur. From these four tehsils, 1116 water samples were collected to evaluate the actual situation in connection with arsenic contamination. From Sadiqabad Tehsil, two hundred and ninety eight water samples were analysed from 29 Union Councils. Only 57 samples (19.12 %) exceeded the limits of 10 ppb whereas 9 water samples (3.02 %) exceeded the arsenic concentration limit of 50 ppb (Table-5).

Table-5 Arsenic in Ground Water (Rahim Yar Khan)

Arsenic contents in 63 water samples (20.86 %) out of 302 collected from 39 Union Councils of Tehsil Rahim Yar Khan had more than 10 ppb of arsenic and 12 samples (3.97 %) had arsenic concentration above 50 ppb (Table-5). Out of 262 water samples collected from 27 Union Councils of Tehsil Khanpur, only 15.64 % samples had arsenic concentration more than 10 ppb, whereas 1.90 % samples had arsenic greater than 50 ppb (Figure-6&7).

Fig.-6: %age of Samples > 10 ppb (Rahim Yar Khan District)

Whereas in Tehsil Liaqatpur, 18.50 % sample exceeded the WHO limit of 10 ppb of arsenic and 2.36 % samples exceeded the arsenic concentration level of 50 ppb (Figure 6&7). The data showed that water samples of Tehsil Rahim Yar Khan had highest arsenic contamination and Tehsil Khanpur had the lowest arsenic contamination (Figure-6). Overall results of district Rahim Yar khan showed 18.63% samples having arsenic concentration above 10 ppb and 2.86% samples having arsenic concentration beyond 50 ppb (Table-5).

 Fig.-7: Arsenic in Ground Water Samples > 50 ppb (Rahim Yar Khan District)

Whereas, 27 Samples (2.41%) of Rahim Yar Khan District fell in the range of 50-100 ppb of arsenic (Table-6). Whereas only 4 samples (0.35%) were found beyond 100 ppb arsenic concentration as shown in Table-7.

Table-6 Ground Water Samples of Rahim Yar Khan District Having Arsenic (50-100 ppb)

Table-7 Ground Water Samples of Rahim Yar Khan District with Arsenic above 100 ppb

4.1.3 Arsenic in Multan District

The Multan District has four tehsils namely, Multan City, Multan Saddar, Shujaabad and Jalalpur Pirwala. In total 521 water samples from four tehsils of Multan District were collected and analyzed. The results showed that 40 samples (71.42 %) out of 56 samples of tehsil Multan city exceeded 10 ppb limit, whereas only 7 samples (12.5 %) crossed the arsenic concentration level of 50 ppb (Table-8).

Table-8 Arsenic in Ground Water (Multan)

Incase of Tehsil Multan Saddar, 90 water samples (31.91 %) exceeded from 10 ppb and only 3 samples (1.06 %) were exceeded arsenic concentration of more than 50 ppb (Table-8). Similarly, 34 samples (42.5 %) out of 80 samples collected from 16 union Councils of Tehsil Shujaabad were found beyond 10 ppb limit and only one sample (1.25 %) above 50 ppb limit. Analytical data of 103 water samples collected from 14 Union Councils of Tehsil Jalalpur Pirwala revealed that 31.06% samples had arsenic concentration more than 10 ppb and 3.88% beyond 50 ppb (Fig. 8 & 9).

Fig.-8: %age of Samples > 10 ppb (Multan District)

Fig.-9: Arsenic in Ground Water Samples > 50 ppb (Multan District)

Overall, 37.61% samples in Multan District exceeded the 10 ppb arsenic concentration limit and 2.87% samples exceeded the arsenic limit of 50 ppb (Table-8). A comparison of all the Tehsils of Multan District have revealed that Tehsil Multan city is having highest arsenic contamination level for the both ranges of above 10 ppb and above 50 ppb, whereas Tehsil Jalalpur Pirwala have shown lowest arsenic percentage for the same category with arsenic concentration above 10 ppb (Figure-8) whereas Tehsil Multan Saddar have shown the lowest arsenic concentration above 50 ppb (Figure-9). Moreover, out of 521 water samples (1.72%) were found between 50-100 ppb, whereas only 6 samples (1.15%) were found with arsenic concentration more than 100 ppb (Tables-9 & 10).

Table-9 Ground Water Samples of Multan District Having Arsenic (50-100 ppb)

Table-10 Ground Water Samples of Multan District with Arsenic Above 100 ppb

4.2 District-wise Comparison

In Southern Punjab, 37.61% water samples collected from Multan District exceeded WHO threshold value of arsenic of 10 ppb (Figure-10). Whereas, 18.33% and 18.63% water samples from Bahawalpur and Rahim Yar Khan Districts exceeded the WHO threshold values. On the other hand, percentage of groundwater samples exceeding 50 ppb in Bahawalpur District is comparatively high i.e. 3.16% more than the other two districts (Figure-11). Overall 22.67% and 2.79% water samples were found unsafe with respect to WHO and PSQCA standards respectively (Figure-12).

Fig.-10:  %ages of Samples exceeding 10 ppb (Cities of Southern Punjab)

Fig.-11: %ages of Samples exceeding 50 ppb (Cities of Southern Punjab)

Water samples of three districts having arsenic between 50-100 ppb and above 100 ppb is shown graphically in Figure-13.

Fig.-12:  Overall Results of Samples Exceeding 10 ppb & 50 ppb

Fig.-13:  %age of samples falling in 50-100 & above 100 ppb (Cities of Southern Punjab)

Data of all the water samples analyzed at PCRWR water quality laboratory alongwith relevant information of Union Council, Village etc. are given in Annexure III. Map indicating the affected areas highlighted by red colours is given as Figure-14.

4.3 Summary of Arsenic Contamination in Southern Punjab

Table-11 gives an overall summary of arsenic in three districts. According to analytical data, 543 samples (22.67%), out of 2395 were found to be having arsenic concentration above the WHO guidelines of 10 ppb and only 67 (2.79 %) of the sample were found beyond 50 ppb limit.

Table-11 Arsenic in Ground Water of Southern Punjab

4.4 Possible Causes of Arsenic Contamination in Southern Punjab

Findings of this study have clearly shown the present situation of arsenic contamination in the Southern Punjab. The most spectacular example of arsenic poisoning and its suffering is Bangladesh. As compared to Bangladesh as well as other affected areas of the world, %age of arsenic contamination in the groundwater of Punjab is considered as very low, but the present situation of presence of arsenic contamination in the groundwater is of higher concern. Bahawalpur, Rahim Yar Khan and Multan districts are the important districts of Punjab Province having 11.8% of the population of Punjab.

The presence of arsenic in drinking water can create many diseases associated with arsenic contamination. Generally, if arsenic is present in drinking water, it suggests that arsenic contamination would be taking place through food chain, soil and crops irrigated with arsenic contaminated water. Consumption of these contaminated commodities may cause medical problems ranging from gangrene of the peripheral organs to skin cancer. Common water sources used in these districts are hand pump, pond, well, and tube well. To know the basic cause of arsenic in groundwater, geological, geo-morphological and geo-hydrological conditions of these affected areas are important to know. Geology and water chemistry of these areas is not much clear but the possible prediction as a cause of the arsenic in groundwater may be the result of the strong influence of water-rock interactions and the greater tendency in aquifers for the physical and geochemical conditions to be favorable for arsenic mobilization and accumulation. Other reasons may be industrial activities in these districts. There are a  number of pesticides, fertilizers, chemical, agricultural and other industries established in various tehsils of these districts especially in District Multan and Rahim Yar Khan. So the industrially induced arsenic pollution due to drainage of industrial wastes especially of pesticide industries may be possible cause of arsenic in groundwater.

The characteristic chemical features of groundwater with high arsenic are high iron, manganese, bicarbonate and often phosphorus concentrations and low chloride, sulphate, nitrate and fluoride concentrations with pH value close to or greater than 7 (Pauline, L.S and David, G.K, 2002). So the higher arsenic concentration in groundwater may become the reason of other problems caused by increased concentrations of iron, manganese, bicarbonate or phosphorus. Therefore, detailed monitoring is recommended to discover complete picture. How many people are suffering from arsenic related diseases in these affected areas that remain to be established? The total area of the affected districts is 40,350 Sq. Km with a population of 3,116,851. This does not mean that at present all of the 3,116,851 people are drinking arsenic contaminated water and that the whole area of 40,350 Sq. Km. is contaminated by arsenic.

At last but not atleast, now the important task is to develop remedial measures to rectify the problem, as arsenic poisoning is a great threat to the lives of every age group especially infants and pre-school aged children since their skin surface area, body weight ratio is significantly higher than adults and because their skin may allow more arsenic absorption.

4.5 Review of Arsenic Data Generated by Kits

Results of 11, 975 water samples analyzed using arsenic field testing kits were examined in the light of the guideline values. Overall 14.21 % samples exceeded WHO guidelines value of arsenic of 10 ppb, whereas only 1.92 % samples exceeded from PSQCA value of 50 ppb (Table-12).

Table-12 Arsenic Levels in Ground Water of Southern Punjab (Field Testing Kits Data)

Whereas 63.94% samples were found arsenic free, fit for drinking and domestic purposes. Data of Multan District analyzed by field testing kit have shown highest %age for the samples exceeding 10 ppb (34.16%) and 50 ppb (3.49%) (Table-13).

Table-13 Arsenic in Ground Water of Southern Punjab (Field Testing Kits Data)

Whereas Rahim Yar Khan District showed lowest %ages (7.90%) and (0.98%) of samples having arsenic contamination above 10 ppb and 50 ppb (Table-13). According to data produced by field-testing kit, Multan District showed highest %age i.e. 2.34% for samples falling in the range of 50-100 ppb (Table-14). Whereas 1.74% samples of Bahawalpur District showed tremendous contamination range of between 101-1000 ppb and the status of arsenic in ground water of Rahim Yar Khan District was lowest in the range of 51-100 ppb and 101-1000 ppb (Table-14).

Table-14 District-Wise Arsenic Status (Field Testing Kits Data)

4.6 Comparison of Analytical Techniques of Analysis Used for This Study

Twenty percent samples (tested by field testing kits) were analyzed on Atomic Absorption Spectrophotometer (AAS) at PCRWR water quality laboratory to check the reproducibility and reliability of field testing kits. The details of results produced through field testing kits are given in Annexure-III. Comparison of these results with the results generated by PCRWR on the high-tech and state of art equipment i.e. Atomic Absorption Spectrometer revealed that analytical data of field testing kits for 42.63% samples gave the difference of + 5 ppb, whereas 18.99% samples showed a difference of +10 ppb, about 12% and 7% samples showed the difference of + 20 ppb and + 30  ppb respectively (Table-15).

Table-15 Comparison of Data Generated by Arsenic Field Testing Kit & AAS

A difference of + 5 is ignorable when compared the results of AAS with testing kits, whereas a difference of + 10 ppb is also acceptable under certain conditions. However, a difference of + 20 ppb & + 30 ppb is not acceptable by the Scientific Community and fall in the category of error.

Comparison of analytical techniques (Atomic Absorption Spectrophotometer and Arsenic Field Testing Kit) revealed that results given by both techniques for samples of Multan District having arsenic contamination >10 ppb are quite close to each other i.e 37.61% by AAS and 34.16% by kit. Whereas Bahawalpur and Rahim Yar Khan Districts showed a difference of 8.68% and 10.73% respectively between the results of both techniques (Table-16).

Table-16 Comparison of Analytical Techniques

This variation may be due to the difference of visual sensation of color given by testing kit which varies person to person. Therefore, this difference is ignorable provided the emphasis is placed on careful observation of color indicated by field testing kit for arsenic concentration. There is very less percentage difference between the results of samples exceeding 50 ppb, 50-100 ppb and above 100 ppb analyzed by both the techniques as shown in Figures 15, 16, 17 and 18.

Fig.-15 Comparison of Atomic Absorption Spectrophotometer & Arsenic Testing Kit (>10 ppb)

Fig.-16 Comparison of Atomic Absorption Spectrophotometer & Arsenic Testing Kit (>50 ppb)

Fig.-17 Comparison of Atomic Absorption Spectrophotometer & Arsenic Testing

 Kit (50-100 ppb)

Fig.-18 Comparison of Atomic Absorption Spectrophotometer & Arsenic Testing

Kit (>100 ppb)

Furthermore, it is concluded that results of arsenic field testing kit are reliable and considerable for field testing of water samples. To ensure the accuracy, reliability and actual position, it is highly recommended that water samples must be analyzed on the Atomic Absorption Spectrometer (AAS), if this state of the art equipment is available.

4.7 Arsenic Removal Technologies as a Solution

Review of arsenic removal technologies have revealed that many technologies have been developed in many parts of the world for the removal of arsenic with applicability at large municipal treatment plant or at community or household levels. All of the technologies for arsenic removal rely on a few basic chemical processes such as oxidation-reduction reactions, precipitation, adsorption and ion exchange, solid liquid separation, physical exclusion and coagulation.

These technologies remove arsenic but have some drawbacks such as high cost, unsound technologies, energy dependent, post treatment requirement etc. In recent years, a tremendous amount of research has been conducted to identify novel technologies for arsenic removal particularly with low cost and low technology system.

Presence of excessive levels of arsenic in ground water of areas of Punjab province has attained greater attention as the affected areas of the Punjab province such as Districts of Multan, Bahawalpur and Rahim Yar Khan has an estimated population of 3,116,851. Major part of the population is from rural areas where the people are not aware of the health hazards of arsenic contamination in the drinking water. As arsenic is tasteless, colorless and odorless even at higher concentration in many cases damage is done before knowing the cause. The magnitude of complexities of the arsenic problem makes it extremely difficult problem to handle. Added to this, socio-economic situation of the people of these areas is very much important to control this problem. Most of the Southern Punjab depends on groundwater for drinking, cooking and other domestic purposes. The presence of excessive arsenic beyond the WHO guideline value in groundwater of such areas has necessitated the need for a simple and low cost technique for the removal of arsenic from drinking water. Considering the socio-economic background of rural and urban population of these areas, it was highly needed to develop a simple, an appropriate and affordable household filtration system to combat the situation. Therefore, PCRWR has developed a low cost technology for the removal of arsenic from drinking water. PCRWR has recently successfully completed the work on three options of arsenic removal technologies. These technologies will be promoted in the affected districts in near future with the coordination of UNICEF.

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