Determining the concentrations of radon and the rate of annual effective dose in some types of drinking water available in the Iraqi markets

           In this research, radon concentrations in some types of healthy drinking water samples available in Iraq's market were measured using a technique called Durridge RAD-7-H2O with closed loop. Then the rate of annual effective dose in human taken this water is determined. 
          It was found that, radon concentrations in studied samples ranged between 1.2 Bq.m-3 to 142 Bq.m-3. The results of the radon concentrations and the rate of annual effective dose for drinking water samples were significantly lower than the USEPA and WHO recommended limits that equal 500 Bq/m3 and 1 mSv/y respectively.


Introduction
Radon is a gas that has no color, odor, or taste and comes from the natural radioactive decay of uranium in the ground.Human exposed to radon by two main sources: radon in the air in home (frequently called "radon in indoor air") and radon in drinking water.Radon can get into the air breathe and into the water used for drinking.Radon is also found in small amounts in outdoor air [1,2].Breathing radon indoor air can cause lung cancer.Radon gas decays into radioactive particles that can get trapped in lungs when breathe it.As they decay further, these particles release small bursts of energy.This can damage lung tissue and increase chances of developing lung cancer over the course of lifetime.People who smoke have an even greater risk.Not everyone exposed to high levels of radon will develop lung cancer.However, radon indoor air is the second leading cause of lung cancer.About 20,000 deaths a year in the U.S. are caused by breathing radon indoor air.Only about 1-2 percent of radon in the air comes from drinking water.However breathing radon increases the risk of lung cancer over the course of lifetime.Some radon stays in the water; drinking water containing radon also presents a risk of developing internal organ cancers, primarily stomach cancer.However this risk is smaller than the risk of developing lung cancer from radon released to air from tap water.Based on a National Academy of Science report, EPA estimates that radon in drinking water causes about 168 cancer deaths per year: 89% from lung cancer caused by breathing radon released to the indoor air from water and 11% from stomach cancer caused by consuming water containing radon [3][4][5].Not all drinking water contains radon.If drinking water comes from a surface water source, such as a river, lake, or reservoir, most radon that might be in the water will be released into the air before reaching water supplier or home.Radon is only a concern if drinking water comes from underground, such as a well that pumps water from an aquifer, though not all water from underground sources contains radon.Many people realize that the quality of drinking water is not ideal.Maybe it's the taste or odor.Perhaps it's the various chemicals in the water (some are added on purpose and some are from pollution).Some people think that the dissolved minerals in the water are good and others think they're bad.There are some scientists modernly using RAD-7 detector to measure concentration of radon water.R.K. Somashekar et al. in (2010) [6] studied the distribution of radon 222 Rn activity concentration in groundwater samples and their annual effective dose exposure in the Varahi and Markandeya command areas.Radon measurement was made using Durridge RAD-7 radon-in-air monitor, using RAD H 2 O technique with closed loop aeration concept.A. R. Subber et al. in(2011) [7] studied the methods to measure radon in in surface, underground water and oil-produced water separated from oil in Basra Governorate in Iraq using fast electronic techniques RAD-7 and the passive method by using the solid state nuclear track detectors CR39 and L115-II.And H. Al Zabadi et al. ( 2012) [8] used RAD-7 detector for measuring the concentration of radon for drinking water supplies in Palestine.The aim of this study was determined the important radioactive element radon in healthy drinking water, because several factors such as increases used it and availability in markets different types.

Sampling and assays
Water samples were taken from Iraq market (Iraq samples).Radon concentrations in these samples were measured with RAD-7 an electric radon detector connected to RAD-H 2 O accessory (Durridge Co,USA, 2010) for a period of one month .Figure (1) shows the schematic diagram of RADH 2 O .In the setup of RAD-7 detector was used for measuring radon in water by connecting it with a bubbling kit which enables to degas radon from a water sample into the air in a closed loop.A sample of water was taken in a radontight reagent bottle of 250 mL capacity connected in a close circuit with a zinc sulphide coated detection chamber which act as scintillator to detect alpha activity and a glass bulb containing calcium to absorb the moisture, air was then circulated in a close circuit for a period of 5-10 min until the radon was uniformly mixed with the air and the resulting alpha activity was recorded and it directly gives the radon concentration.The radon concentration of drinking water is an important issue from the dosimeter aspect, because more attention is paid to the control of public natural radiation exposure.The radiation dose due to radon can be divided into two parts, the dose from ingestion and the dose from inhalation.
Radon is soluble in water and this route of exposure is important if high concentrations are found in drinking water [10].On some occasions, water is consumed immediately after leaving the faucet before its radon is released into the air.This water goes directly to the stomach.Before the ingested water leaves the stomach, some of the dissolved radon can diffuse into and through the stomach wall.During that process, the radon passes next to stem or progenitor cells that are radiosensitive.These cells can receive a radiation dose from alpha particles emitted by radon and radon decay products that are created in the stomach wall.After passing through the wall, radon and decay products are absorbed in blood and transported throughout the body, where they can deliver a dose to other organs [11].
The annual effective dose in oranges body in (mS.y -1) due to the ingestion and inhalation of radon, resulting from the radon concentration in domestic water, was calculated according to the following expression [12][13][14]: Annual effective Dose (Sv.y -1 ) = A (Bq/l) × V(l/y) × CF (Sv/Bq) (1) where : A (Bq/L): is the concentration of 222 Rn in the ingested drinking water.V(L/y): is the annual intake of drinking water.CF (Sv/Bq): is the ingested dose conversion factor for 222 Rn.Annual effective dose due to intake of 222 Rn from drinking water is calculated considering that an adult (age 18 year), on average, takes 730 L water annually [12].Following ingestion of 222 Rn dissolved in drinking water, a dose conversion factor for all body, lung and stomach were 110, 38 and 73 mSv/Bq respectively [14].

Results and Discussion
Table1 shows the results of concentrations of radon (Bq.m -3 ) and the rate annual effective dose (µSv.y - ) in healthy drink water samples.Table 1 and Fig. 2 show that the sample Al-Naqawa has highest radon concentration 142±0.38Bq.m -3 , and sample Al-Tour has lowest radon concentration 1.2±0.42Bq.m -3 .Also Table 1 and Fig. 3 shows the value of the annual effective dose in all body, lung and stomach for all samples.From the spectra that shown in Figs. 4 and    No.

Concentrations of Radon Bq.m -3
The rates of annual effective dose in (µSvy The reason for vibration in radon concentration could be a function of geological structure of the area, water source and differences in the climate.Others have reported that the geological structure of an area is a predominant factor for high radon concentration and climate is also an important factor [17].

Conclusions
In this paper the results of the 222 Rn measurements in 14 bottled drinking waters are presented.The measurements were performed by RAD-7 radon detector manufactured by DURRIDGE company Inc.From the results for the bottled drinking water, it can be concluded that the majority of bottled drinking water is safe to use from the standpoint of concentration of radon in them.

Fig. 3 :
Fig.3: The rates of annual effective dose of radon concentration in healthy drinking water samples.

-1 )
[15]tra determined by MCA in RAD-7 system.All results of the annual dose effective for 222 Rn of healthy drinking water were smaller than the normal limits of world 1mSv.y -ults of the average activity concentration222Rn of healthy drinking water were smaller than the accordable limit as reported in USEPA[16].The allowed maximum concentrations level for222Rn in water for human conception is 500 Bq.m -3 . these