RADIOLOGICAL RISK ESTIMATION OF DRINKING AND IRRIGATION WATERFOR SOME EGYPTIAN SITES

The objective of this work was to determine the radiological health risk due to natural radionuclides (e.g., 226 Ra, 228 Ra and 40 K) in drinking and irrigation water resources in different locations in Egypt. The water resources in Egypt are diverse and include the river Nile, ground water, springs and lakes in addition to rain waters. The total annual effective dose in all estimated water resources were ranged from 0.02, 0.03 and 0.03 mSvy-1 to 13.49, 26.13 and 13.13 mSvy-1 for infants, children and adults respectively. The average life-long cancer risk and the average hereditary effects due to ingestion of radionuclides by adults show that 12 out of 10,000 may suffer some form of cancer fatality and 43 out of 1000,000 may suffer some hereditary effects. It is concluded that the radiological health risk data obtained werewithin their safe values.


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Natural radionuclide present in water beyond the safe levelscan be considered to have potential risks to human. Increased concern for the radiological status of drinkingwater has led to an increased demand for data on waterquality. The recommended reference dose level (RDL) ofcommitted effective dose is 100 μSv from oneyearconsumption of drinking water (WHO, 2008). Gamma rays can enter the skin and interact with tissues or organs. Uranium andradium found in water do not emit strong gamma radiation, so showering with that water will not pose any significantrisk. However, if this radionuclide is inhaled or ingestedthrough eating and drinking, the emissions rays can comeinto direct contact with sensitive tissues or organs in thebody (Irinaet al.,2011). Findings of many studies have shown that longtermexposure to uranium in drinking water may causetoxic effects to the kidney and can lead to cancer (Irinaet al.,2011).
The potential harmfulness of radionuclides is based on their long half-lives and chemical behavior ( 232 Th: 1.4 × 10 10 yr, 238 U: 4.47 × 10 9 yr and 40 K: 1.28 ×10 9 yr). 232 Th is mainly radiotoxic, 238 U is both radiotoxic as well as chemically toxic whereas 40 K is radiotoxic as well as nutritionally important element (Tykva and Sabol 1995). Owing to the health risks associated with the exposure toindoor radiation, many governmental and international bodies such as the international commission on Radiological Protection (ICRP), the World Health Organization (WHO), etc. have adopted strong measures aimed at minimizing such exposures (ICRP, 2006).
There are a lot of papers discussed the natural radionuclide concentration in water resources in Egypt such as(El-Sayed2015, Arafat2017, Yehiaa 2017andAtef 2019) butno attention was paid to estimation of annual effective dose and Cancer and Hereditary Risk. So, this work estimates annual effect dose, Cancer and Hereditary Risks due to 238 U, 232 Th series and 40 K present in water resources samples collected from different locations in Egypt.The obtained data and information from this study are highly needed to provide a basis for the sustainable development strategies in Egypt.

Study Area
The study area is extended along the northern part of Egypt from Sinai governorate in the EasttoMarsaMatrouh governorate in the West. Water samples were collected from selected cities andtowns in the area under investigation (Tap water samples, ground water samples and surface watersamples). The coordinates of all sampling points were identified by the Global Positioning System device (GPS) as shown in figure (1). The collected samples were analyzed using HPGe detector to determine Ra-226, Ra-228 and K-40. The data obtained were used to calculate the annual dose for different organs from consumption of water for four age groups (5 years, 10 years, 15 years and adults) using Acute Dose calculator program and the results were previously published (Atef, et.al., 2019).
In the present work, the specific activities of 226 Ra, 228 Ra and 40 K were used to estimate Cancer and Hereditary Risk for the studied area.Also, to obtain a complete overview about the Cancer and Hereditary Riskfor different water resources in Egypt, the published results of 226 Ra, 228 Ra and 40 K of El-Alamein-Alam El-Rum Area (harvested rain water) (El-Sayedet.al., 2015).Marsa Allam area (ground water) (Arafatet.al., 2017) and Northern area of the western desert (ground water) (Yehiaaet.al., 2017)were used to estimate the total annual effective dose and Cancer and Hereditary to these regions. 598

Annual Effective Dose
The annual effective dose (AED) due toingestion of water was computed using thefollowing formula (UNSCEAR 2008).
Where; DCF ing (i) is the dose coefficient of a particularradionuclide in Sv. Bq -1 for a particular age category. A i isthe specific activity concentration of radionuclide in thewater sample measured in Bq. l -1 and L is the radionuclideintake in liters per year for each age group categories.

Cancer and Hereditary Risk
In addition to the estimated annual effective dose, the risk incurred by a population is estimated by assuming a linear dose-effect relationship with no threshold as per ICRP practice. For low doses ICRP fatal cancer risk factor is 5.5 × 10 -2 Sv -1 (IAEA 2004). The risk factor states the probability of a person dying of cancer increases by 5% for a total dose of 1 Sv received during his lifetime. Therefore, the probability of death from cancer due to 'natural incidence' increases from about 25% to 30% following a total lifetime exposure of 1 Sievert.

Radioactivity measurements
The specific activity concentrations of the measured samples are under the detection limit of the used analytical procedures (0.7 Bq L -1 for 226 Ra and 0.6 Bq L -1 for 228 Ra) while, 40 K isthe only detected radionuclide.The specific activity concentrations results of 40 K of water resourcesranged from < DL to 5.30 Bq L -1 with a mean 1.06 Bq L -1 for tap water, ranged from< DL to 5.16Bq L -1 with a mean of 1.01Bq L -1 for ground water, and ranged from < DL to 32.09 Bq L -1 with amean of 3.16 Bq L -1 for surface water (Atef, et.al., 2019).The specific activity concentrations ofharvested rain water collected from El-Alamein-Alam El-Rum Arearanges from<DL to 4.16, from <DL to 3.45 and from <DL to 26.18 Bq/lfor 226 Ra, 232 Th, and 40 K, respectively [10].The specific activity concentrationsof ground water samples collected from marsaallam area ranges from<DL to 10.66, from <DL to 2.33 and from 6.89to 54.31Bq/l for 226 Ra, 232 Th, and 40 K, respectively(Arafatet.al., 2017).
These results are comparable with the results of 15 different water samples (wells and springs) collected from Elba protective area, south-eastern desert of Egypt ( 226 Ra, 232 Th and 40 K ranged from 1.6 to 11.1 Bq/L, from 0.21 to 0.97 Bq/L, and from 9.1 to 23 Bq/L respectively) (El Arabiet.al.,2006) and higher than the activity concentrations levels for water (surface and groundwater) samples collected from the west bank of the Nile River in Assiut Governorate, Egypt ( 226 Ra, 232 Th and 40 K ranged from0.0192 to 0.492Bq/L, from 0.015 to 0.351Bq/L, and from 0.05to 2.25Bq/L for 226 Ra, 232 Th, and 40 K, respectively)(El-Gamalet.al.,2019).

Radiation Dose Estimation and the estimated Cancer Risks and the Hereditary Effects
The annual effective dose for different age groups calculated for 30 water samples collected from different locations from Egypt presented in table 1 considering the ingestion of 226 Ra, 232 Th and 40 K in drinking water. While the estimated Cancer Risks and the Hereditary Effects of adult member of the public are presented in table [2]. In our pervious study (Atef, et.al., 2019) all water resources under investigation, the lower age is the higher the annual effective dose. For tap water, the highest annual dose delivered to 5 y age group (6.16 μSvy -1 ) with a mean of 1.32 μSv y -1 and the lowest annual dose delivered to adults with a maximum of 1.79 μSvy-1 and a mean of 0.33 μSvy-1. For ground water, the highest annual dose (6.12 μSvy -1 ) delivered to 5 y age group with a mean of 1.35 μSv y -1 , and the lowest annual dose delivered to adults with a maximum of 1.71 μSvy-1 and a mean of 0.34 μSvy -1 (Atef, et.al., 2019).
The annual effective dose of the harvested rain water (Table 1) for infants ranged from 0.02, 0.1and 0.01mSvy -1 to 0.6, 0.23, and 0.02 mSvy -1 for 226 Ra, 228 Ra, and 40 K respectively. The annual effective dose of the harvested rain water for children ranged from 0.04, 0.01, and 0.02mSvy -1 to 1.16, 0.35and 0.05mSvy -1 for 226 Ra, 228 Ra, and 40 K respectively. The annual effective dose of the harvested rain water for adultsranged from 0.03, 0.05, and 0.05mSvy -1 to0.84, 1.54and 1.01mSvy -1 for 226 Ra, 228 Ra, and 40 K respectively. The total annual effective dose ranged from 0.03, 0.05 and 0.05 mSvy -1 to 0.84, 1.54, and 1.01 mSvy -1 for infants, children and adults respectively. The children have the maximum total dose values because the children have the maximum annual effective dose values for 226 Ra.The adults have the maximum annual effective dose values for 228 Ra and 40 K. Table 1 indicates that the annual effective dose of the ground water (Marsa Allam area) for infants ranged from 0.36 and 0.01mSvy -1 to 1.09 and 0.02 mSvy -1 for 226 Ra and 40 K respectively. The annual effective dose of the ground water (Marsa Allam area) for children ranged from 0.7 and 0.02mSvy -1 to2.13 and 0.06 mSvy -1 for 226 Ra and 40 K respectively. The annual effective dose of the ground water (Marsa Allam area) for adults ranged from 0.35 and 0.03mSvy -1 to 1.06 and0.08mSvy -1 for 226 Ra and 40 K respectively. The total annual effective dose ranged from 0.01, 0.02 and 0.03 mSvy -1 to 1.12, 2.18, and 1.14 mSvy -1 for infants, children and adults respectively. Table 1 indicates that the annual effective dose of the ground water (Northern area of the western desert) for infants ranged from 2.85, 0.07 and 0.01mSvy -1 to13.24, 0.39 and 0.02mSvy -1 for 226 Ra, 228 Ra, and 40 K respectively. The annual effective dose of the ground water (Northern area of the western desert) for childrenranged from5.02, 0.11, and 0.01mSvy -1 to20.63, 0.58, and 0.04mSvy -1 for 226 Ra, 228 Ra, and 40 K respectively. The annual effective dose of the ground water (Northern area of the western desert) for adultsranged from2.51, 0.13, and 0.01mSvy -1 to 12.87,0.66, and0.05mSvy -1 for 226 Ra, 228 Ra, and 40 K respectively. The total annual effective doseranged from 2.80, 5.34 and 2.88mSvy -1 to 13.49, 26.13 and 13.31mSvy -1 for infants, children and adults respectively. The children have the maximum total dose values because the children have the maximum annual effective dose values for 226 Ra.The adults have the maximum annual effective dose values for 228 Ra and 40 K.
By comparing all the results in table 2 we can conclude that; the ground water (Northern area of the western desert) Northern area of the western desert has the maximum values for the fatality cancer risk per year, estimated lifetime cancer risk, severe hereditary effects per year and estimated lifetime hereditary Effects.

Conclusion: -
The present work provides information dealing with associated hazards of Ra-226 (U-238) series, Th-232 series and K-40 radionuclides in water resources. Such information should be known before executing the economic projects related to the development process in Egypt. This work depends on laboratory measurements and mathematical calculations. Surface water and tape water have total annual effective dose levelslower than the recommended 603 reference level determined by ICRPwhile ground water and harvested rain water have values more than these recommended reference levels. In all the studied water resources, the estimated fatal cancer risk to adult per year ranged from 1.08×10 -9 to 7.32×10 -7 with the associated lifetime fatality cancer risk ranged from 7.55×10 -8 to 5.12×10 -5 . And the estimated hereditary effect to adult per year ranged from 3.92×10 -11 to 2.66×10 -8 with its associated lifetime hereditary effect ranged from 2.74×10 -9 to 1.86×10 -6 .