Evaluation of human risks of surface and groundwater contaminated with 1 Cd and Pb south of El-Minya Governorate , Egypt

8 Water pollution with Cd and Pb has worldwide concern because of their health impact. 9 Evaluation of their concentrations and potential human health risks of surface and 10 groundwater south El-Minya Governorate, Egypt is the main aim of the study. Fifty-five 11 samples were collected; 30 samples surface water and 25 samples groundwater. The samples 12 were analyzed using Atomic Absorption Spectrometry (AAS) to determine Cd and Pb 13 contents. The heavy metals levels in both of surface and groundwater exceeded the maximum 14 allowable level for drinking water which set by WHO. The hazard quotient and hazard index 15 showed that groundwater may pose a health risk to residents, especially the children, 16 primarily due to the high Cd content. In addition, there might be some concern for adverse 17 Carcinogenic health effects. The pollution returns to human activities. The water can be 18 recommended for irrigation not for drinking. 19


Introduction
Water pollution resources pollution was becoming a worldwide problem.To protect the environment and public health, it is important to have precise knowledge on amount and type of water pollutants especially heavy metals.Because the heavy metals have long  (Sadek 2001).The aquifer is underlined by impermeable Pliocene clay layer and overlain by semi-permeable silty clay layer.The semi-confined bed (silty clay) is missed outside the floodplain and the aquifer becomes unconfined westward in the desert fringes.The groundwater flows generally from the southern part to the northern part of the study area.Locally, the groundwater flows from the center outwards in all directions; therefore, the River Nile is a recharge zone.The aquifer is recharged by Nile water, irrigation system, drains, agricultural infiltration and vertical upward from the deeper saline aquifers (Korany, 1984).

Material and methods
In November 2014, thirty water samples were collected from surface water resources at the study area (Fig. 1 and Table .1).In addition, 25 groundwater samples were collected from the Quaternary aquifer (Fig. 1).Pre-rinsed polypropylene bottles were filled with the samples, sealed tightly.At lab the samples were filtered through filter paper (Whatman No. 42) and digested with nitric acid (APHA, 1995).Samples were analyzed using atomic absorption spectrometer instrument (model: Perkin Elmer 400) in National Research Centre Laboratories.
For health risk assessment, two major indices, chronic daily intake (CDI, mg/kg/day) and hazard quotient (HQ) for each contaminant was calculated according to the following equations (Eq. 1, 2, 3) adopted by Kelepertzis (2014)

Surface water
River Nile and its tributaries (canals and drains) are the main source of water in Egypt especially for the governorates allocated on the river banks and on its branches.Therefore, the quality of water was evaluated by measuring of Cd and Pb concentrations in south of El-Minya Governorate during 2014 (Table 2).The close difference between mean and median (Table 2) indicate the homogenous distribution of both metals and the unity of their source.
Cadmium concentrations (Table 2), ranged from 1 to 48µg/l, exceed the permissible limit (3µg/l) for drinking water according to WHO (2011).Excess Cd could accumulate in the kidney and remains for many years causes irreversible kidney damage (Goyer, 1996) -Kammar, 1974).Pesticides also can lead to high Cd content in the study area (Bowen, 1966).
The highest concentration of Cd was recorded in sample number S 8 of 48µg/l close to Abu Qurqas Sugar factory due to throwing of human wastes or garbage (Al-Shiekh Sharf canal).The lower concentration was recorded in sample number S 6 (1µg/l) which was picked up from the River Nile.These results are in line with those obtained Toufeek (2011) who recorded average Cd concentration 12.5 µg/l at Aswan (southern Egypt), while Salman (2013) found that the Cd level in samples collected from Sohag Governorate were flocculated around 16µg/l.Therefore, Osman and Kloas (2010) mentioned that the average Cd concentration in the River Nile at Assuit was 6 µg/l.
Lead concentration ranged from 54 to 329µg/l in the studied surface water samples (Table .2).The study samples content of Pb passes the permissible limit (10µg/l) for drinking water according to WHO (2011).Lead adsorbed by human body disturbs many body processes and is harmful to many organs and tissues such as heart, bones, nervous system (Needleman, 2004;Bruce et al., 2012)

Groundwater
Groundwater is the second important water resources in the study area and the only water resource in the desert fringes.It is used for irrigation and unfortunately for domestic and drinking in some villages which lacking safe potable water source.The groundwater samples exhibit relative wide range of the Cd level varying from 2 to 49µg/l with mean value 24µg/l (Table 3).The groundwater Cd level decreased eastward (Fig. 3) due to mixing with the surface water from River Nile and the role of the silty clay layer in the absorbance of Cd and prevent it to reach the aquifers.However, there are three hot spots of Cd resulted from the intensive human activities and fuel stations.Cd hot spot in the NW part of the study area adjacent to the western desert road was developed as a result of the unconfined condition of the aquifers which become vulnerable to contamination.
Also, the measured Pb content of the analyzed groundwater samples show relative wide range varying from 90 to 410µg/l with an average of 242µg/l (Table .3).The marked high level of Pb content implies that the anthropogenic activities are the main source of Pb.
The results are in agreement with Melegy et al (2014) who mentioned that Cd and Pb concentration in the groundwater of Sohag were around 21 and 383 µg/l, respectively.In addition, Salman (2013) reported that the average of Cd and Pb concentrations are 21 and 383µg/l respectively in the Quaternary aquifer at Sohag.Pb level in the groundwater of the study area was increased at Abu Qurqas district resulting from the effect of the sugar factory, cesspits and fuel stations (Fig. 4).
All the samples are unsuitable for drinking purpose where they possess Cd and Pb values above the permissible limit of 3µg/l for Cd and 15 µg/l for Pb (WHO, 2011).On the other hand, surface and ground water are suitable for irrigation purposes according to NAS-NAE (1973), where they contain less than 10000 and 5000000µg/l of Cd and Pb, respectively.
But unfortunately, using the groundwater for drinking in some villages of the study area Drink.Water Eng.Sci.Discuss., https://doi.org/10.5194/dwes-2018-37 Drinking

Health risk assessment
It was observed that general population in the rural area is using groundwater from hand pumps for drinking and domestic purposes because they don't have access to the tap water from the tube wells.Therefore, health risk assessment for groundwater was carried out in this study.The results of non-carcinogenic and carcinogenic health risks due to metal exposure in groundwater samples are provided in Table ( 4).
The values of non-carcinogenic health risk of Cd in drinking water for adults range from 0.11 to 2.68 with an average of 1.29 and for children extend between 0.16 and 4.03 averaging 1.94 (Table 4).The Pb values for adults range from 0.04 to 0.20 with an average of 0.12 and for children vary from 0.07 to 0.31 averaging 0.18.According to USEPA (2011), Cd and Pb values of non-carcinogenic health risk should not exceed 1 to be considered as nonharmful drinking water.
The Cd values of carcinogenic health risk for drinking water was ranged from 4.8*10 -6 to 1.2*10 -4 averaging 5.66*10 -5 for adults and from 2.9*10 -5 to 7.11*10 -4 with an average of 3.42*10 -4 for children.Pb values for adults extend between 3.13*10 -5 and 14.3*10 -5 with an average of 8.41*10 -5 , while the results for children vary from 1.67*10 -9 to 86.1*10 -5 averaging 48.5*10 -5 (Tables 4).According to USEPA ( 2011), the values of Cd and Pb of carcinogenic health risk should not exceed 10 -6 which it is the safe limit of the hazard index.More than this limit, the drinking water has very harmful effects on the inhabitants.

Conclusion
Cadmium and lead contents of the studied samples from Nile River, its tributaries (canals and drains) and groundwater exceed the permissible limits for drinking water and The non-carcinogenic health risk of Cd values exceeds 1 which is the safe limit of the hazard index indicating harmful drinking water while the Pb values do not pass that limit.The values of Cd and Pb of carcinogenic health risk exceed the safe limit of the hazard index and accordingly the drinking water has very harmful effects on the inhabitants.
The water resources in the study area (surface and groundwater) are suitable for irrigation purposes.Source of pollution in the investigated area were derived from anthropogenic activities such as industries, agriculture, mining and sewage.The water in concerned area is suitable to use for irrigation purpose and unsuitable for drinking.

Recommendations
It is recommended to connect the houses in different rural parts of the study area with safe drinking water lines with regular monitoring of water resources and the end user water lines.
Manuscript under review for journal Drink.Water Eng.Sci. Discussion started: 19 December 2018 c Author(s) 2018.CC BY 4.0 License.and shale lenses; Pleistocene sand and gravel with clay lenses and Holocene silt and clay.The main aquifer in the study area is represented by Pleistocene sediments which compose of sand and gravel of different sizes with some clay intercalation.The thickness of this aquifer ranged from 25 to 300 m from desert fringes to central Nile Valley review for journal Drink.Water Eng.Sci. Discussion started: 19 December 2018 c Author(s) 2018.CC BY 4.0 License.represents serious health impact.El-Minshawy and Kamel (2006) mentioned that the use of unsafe water for drinking contributes up to 71.8% of the renal failure in the study area.
Drink.Water Eng.Sci.Discuss., https://doi.org/10.5194/dwes-2018forjournal Drink.Water Eng.Sci. Discussion started: 19 December 2018 c Author(s) 2018.CC BY 4.0 License.could be disturbing many body processes and are harmful to many organs and tissues such as the heart, bones, kidney and nervous system.The canals are higher in Cd and Pb concentrations than the drains indicating the role of the human activities as a main source of these metals because most of the canals penetrate settlements and adjacent to roads.The lowest concentrations of Cd and Pb were recorded in samples which were picked up from the River Nile.

Figure 1 :Figure 2 :
Figure 1: Location map of the study area.

Figure 3 :Figure 4 :
Figure 3: Spatial distribution map of Cd in the studied groundwater samples.

Table 4 : Statistical parameters of non-carcinogenic and carcinogenic health risks for
review for journal Drink.Water Eng.Sci. Discussion started: 19 December 2018 c Author(s) 2018.CC BY 4.0 License.
5health risks for groundwater samples.