|Year : 2020 | Volume
| Issue : 3 | Page : 171-178
Occurrence of radon contamination in ground water samples of Amritsar city, Punjab, India
Sumit Sharma1, Kamaljeet Kaur1, Amanpreet Kaur2, Ajay Kumar2
1 Department of Applied Sciences, Swami Sarvanand Group of Institutes, Amritsar, Punjab, India
2 Department of Physics, D.A.V. College, Amritsar, Punjab, India
|Date of Submission||11-Jun-2020|
|Date of Decision||05-Jul-2020|
|Date of Acceptance||13-Jul-2020|
|Date of Web Publication||6-Jan-2021|
Source of Support: None, Conflict of Interest: None
In the current examination, the ingestion and inhalation dose measurements for the particular body organs in light of the intake of radon through ground water used by the inhabitants have been surveyed in the various locations of Amritsar province, India, using an electrostatic collection type radon monitor (RAD7) analyzer with RAD-H2O accessory. The mean radon activity level in water was seen to be 5.93 ± 2.34 BqL-1. However, the radiation dose received by all different body organs significantly less than the UNSCEAR and WHO suggested a level of 100 μSvY-1. The annual effective dose for the diverse body organs in view of the intake of radon was additionally ascertained and found the maximum dose for lungs than other organs. The radiation dose received by bronchial epithelium by the means of inhalation was likewise high when contrasted with that by stomach walls through ingestion.
Keywords: Annual effective dose, RAD7, radon, water samples
|How to cite this article:|
Sharma S, Kaur K, Kaur A, Kumar A. Occurrence of radon contamination in ground water samples of Amritsar city, Punjab, India. Radiat Prot Environ 2020;43:171-8
|How to cite this URL:|
Sharma S, Kaur K, Kaur A, Kumar A. Occurrence of radon contamination in ground water samples of Amritsar city, Punjab, India. Radiat Prot Environ [serial online] 2020 [cited 2021 Jan 22];43:171-8. Available from: https://www.rpe.org.in/text.asp?2020/43/3/171/306275
| Introduction|| |
Environmental radiation originates from various naturally occurring and human-made sources. Naturally occurring radionuclides are created in the upper environment and are found in the earth's layer (crust). As they decay, they produce daughter products that are generally short lived and more radio-active. The largest proportion of human exposure to radiation originates from natural sources and from inhalation or ingestion of radioactive materials, i.e., uranium, thorium, and potassium. The largest fraction of natural radiation exposure comes from radon, a radioactive gas. Underground rocks-containing natural uranium consistently releases radon into water in contact with it. Radiation exposure can occur by inhalation, ingestion, injection, or retaining radioactive materials. The International Commission on Radiological Protection (ICRP) suggests that radionuclides in water are absorbed more effectively than radionuclides incorporated in food. Once ingested, the radioactive particles ionize the nearby atoms in the body as the radiation travel through a cell or other material. When groundwater percolates through rocks rich in uranium, it is relied to have a significant level of radon gas in groundwater. Radiological hazards might be possible due to the presence of enormous content of radioactive substances in drinking water. Such risks from drinking water are once in a while of public health significance.
Radon (222Rn) is acquired from radium which itself an individual of radioactive decay series of natural uranium. Radium concentration is higher in stone rocks and uranium minerals which bring higher radon activity in that mineralized areas. In this manner, it is critical to discover the role of topographical structure and sorts of rocks present as a wellspring of radon dissolved in ground water and its concentration in groundwater is also constrained by the hydrodynamic components, radium substance of shakes, and nearness of uranium in the host shake.
As the radio-nuclides concentration in groundwater depends upon lithology, geomorphology, and other topographical conditions of a zone. The groundwater travels through breaks in the bedrock, radioactive minerals can deplete out into the groundwater structure. Regular springs and wells worked in bedrock in such regions have progressively raised measure of natural radio-activity. Since radon is an ideal gas, it can without quite a bit of a stretch travel through permeable media, for instance, dirt or partitioned shake (fragment rocks)., Where these pores are stacked with water, radon is broken down into the water and is then transported by it. The centralizations of radon in water shift, especially, all around higher in groundwater and generally decreased in surface water. At the point when water containing radon is ingested, a radiation dose is gotten by the digestive system of the body. The decay of radon and its short-lived daughters continues to give dose. The most genuine risk of admission of water containing high dissolved radon is stomach and colon tumor. Subsequently, it is important to examine the degree of radon in water samples as it might give the fundamental information about shrouded uranium deposits.
Thus, this exploration represents the variety in radon movement in ground water bodies from different sources such as bore wells and hand pumps which are being utilized for private purposes in the rural and urban areas of Amritsar city, Punjab, and found an evident lack of knowledge of radioactivity and its health hazards, and an overall estimate of the level of awareness on natural radiation level among the residents of study region was quite low. Thus, the issue of radionuclides in indoor facilitates and drinking water is a sensitive topic to address as it's a source of health risk, especially due to the availability of insufficient data on 222Rn in groundwater. Considering the background, further, the estimation of the doses in various internal organs taking into account of this radon data was thought of. In this way, the annual effective dose (AED) for different body organs, i.e., lungs, stomach, colon, gonads, liver, kidneys, and skin because of ingestion and inhalation of radon in drinking water samples of the considered area has been investigated to see any contribution of these doses to the inhabitants of the present study. The main concern of this was to measure the radon level in natural ground water sources and related environments in Amritsar, Punjab, and to prepare the baseline data for general awareness, which further allows radiological mapping assessment in the northern region of India.
Amritsar locale is situated in the northern piece of Punjab state and lies between 31°28'30” and 32°03'15” North latitude and 74°29'30” to 75°24'15” East longitude [Figure 1]. The atmosphere of the region is classified as tropical steppe, semi-dry, and sweltering which are basically dry with amazingly blistering summer and cold winter beside in the midst of south west monsoon season. There are four seasons in a year explicitly cold season from November to March, hot season from April to June, south-west monsoon season from a week ago of June to middle September, and postmonsoon season from September to beginning of November. In the midst cold season, series of western unsettling impacts the atmosphere of the region.
|Figure 1: Map showing the locations of the surveyed area during the present study|
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Amritsar locale falls in between Ravi waterways and Beas stream. Ravi river flows in northwest of the district and forms international border with Pakistan. Beas streams flows in the eastern part of the district. Soils in the western part of the district are coarse loamy, calcareous soils, whereas in the central part of the district soils are fine loamy, calcareous, and are well drained. The soils are Ustochrepts to Haplustaff type. The district forms part of Uppar Bari Doab and is underlain by the formations of Quaternary age comprising of alluvium deposits belonging to vast Indus alluvial plains. Sub surface geological formations comprise of fine to coarse grained sand, silt, clay, and kankar. Gravel associated with sand beds occurs along the left bank of Ravi. The beds of thin clay exists alternating with thick sand beds and pinches out at short distances against sand beds.
| Methodology|| |
Ground water samples were gathered from the various sources such as hand pumps and submersible pumps as these are the principal sources of water in Amritsar city, Punjab. Radon concentrations in the collected 20 samples were determined immediately with the goal that no decay of radon takes place. They were stored in 250 ml vial so that no air particles remain in vial. This makes it conceivable to compute radon concentration only due to water rather than the combination of air and water. These water samples were analyzed using RAD7, which is an online radon monitor for figuring the radon concentration (Durridge Company). RAD7 is a continuous radon gas monitor. It is based on solid-state silicon detector. It contains a hemisphere dome in the middle of device, called internal cell. The volume of internal cell is 0.7 L. At the center of the hemisphere, silicon alpha detector is placed. It is a sophisticated and versatile measuring device capable of complex measurements of radon in soil, air, and water. It is a simplest, easiest, and portable computer-driven electronic instrument to use. The task of RAD7 is divided into two categories.
Purging of RAD7
Before utilizing RAD7, the initial step is to do purging to expel undesired moisture and humidity from the measurement chamber. This should be possible by associating gas purifier to RAD7 instrument with tubes. The Drierite gas purifier is an all-purpose drying unit for the effective and rapid drying of air. It is utilized to keep up a dry atmosphere in storage spaces, vaults, and commercial packages. In the current study, we are utilizing indicating Drierite. Indicated Drierite is impregnated with cobalt chloride. It is blue when dry and changes to pink upon the absorption of moisture. The need of purging is just to obtain relative humidity <10% with the goal that we can collect accurate outcome. Purging can be essentially done by simply associating the inlet of RAD7 at the base of desiccant drying unit and outlet of RAD7 at the highest point of desiccant drying unit. If relative humidity becomes <10%, it suggests that RAD7 is now ready for use.
Determination of radon concentration
Radon concentration was evaluated utilizing RAD7 whose schematic outline is appeared in [Figure 2].,, Set RAD7 at Wat250 mode for discovering radon in water samples. The RAD7's pump will run for 5 min. During the 5 min of pumping, over 95% of the accessible radon is expelled from the water. This evacuated radon gas is sucked through filter into the inlet and reaches the measurement chamber. The voltage of 2000–2500 V is applied among detector and hemisphere, creating an electric field throughout the volume of cell. This electric field drifts the positively charged particles onto the detector. Inside the chamber, Rn-222 decays into a positively ionized Po-218. This emphatically ionized Po-218 will be accelerated toward the detector. The produced Po-218 has a half-life of 3 min. When the short-lived Po-218 nucleus decays upon the detector's active surface, its alpha particle (6 MeV) energy has 50% probability of entering the detector, producing an electrical signal proportional in strength to the energy of alpha particle. This signal is enhanced electronically and changed into a digital signal. This signal will be further processed by a microprocessor that helps to produce the spectrum.
Evaluation of mean annual effective dose
The dose because of radon can be partitioned into two sections, first is dose from ingestion and second is dose from inhalation. The annual mean effective dose for ingestion and inhalation was calculated according to the parameters presented by UNSCEAR report as shown below:
DIngestion = 222Rn conc. × 60 × 10-3 × 3.5
DInhalation = 222Rn conc. × 10-4 × 7000 × 0.4 × 9
Evaluation of radiation dose to internal organs
The radon level in drinking water is an imperative issue from the dosimetry aspect, considering the way that additional attention is paid to the control of natural radiation exposure. As radiation dose to the individuals by and large, as a result of waterborne 222Rn, it was believed that waterborne radon may cause higher risk than all other contaminants in water. Therefore, 222Rn in water is a source of radiation dose to various body organs such as stomach and gastrointestinal tract. Subsequently, radon in water is a source of radiation dose to both stomach and lungs. The annual mean effective dose (Dtotal) for different body organs were determined by the parameters introduced by UNSCEAR report is calculated as:
DTotal = WTissue × D (Ingestion ' Inhalation)
Where, WTissue is the tissue weighting factor i.e., 0.15, 0.12 for lung, colon and stomach, 0.20 for gonads, 0.05 for liver and kidney and 0.01 for skin, respectively, D is the effective dose for ingestion and inhalation calculated separately.
| Results and Discussions|| |
[Table 1] gives the outcomes obtained for the mean 222Rn action level in various water samples inspected alongside their respective annual effective dose to the individual anticipating annual consumption of the evaluated volumes of water. The 222Rn activity level is in range of 2.26–13.70 BqL-1 with an average value of 5.93 ± 2.34 BqL-1. These amounts are well inside the reference range suggested by UNSCEAR and the limit prescribed by European Commission. The World Health Organization (WHO) has suggested a treatment level of 100 BqL-1 for radon in drinking water supplies. All samples were found within the limit endorsed by the WHO. The lower and upper quartile of 222Rn concentration is 4.83 and 6.93 BqL-1. This infers 25% samples contain radon concentration in drinking water samples of Amritsar province were below 4.83 BqL-1 and 75% of the samples were underneath 6.93 BqL-1. The variations of radon concentration in different locations are appeared in [Figure 3]. [Figure 3] shows the frequency outline of mean radon concentration in the studied dwellings. Since the distribution of radon in water samples has been found to be lognormal, geometric mean and standard deviation values have been calculated and represented in [Table 1]. The positive estimation of mean radon concentration in considered samples demonstrated a platykurtic distribution with a well-defined central peak. The mean concentration of radon is slightly positively skewed meaning that majority of the data are lower than the average values. The mean radon concentration obtained in the present examination were equivalent to that detailed by Sharma et al. in Amritsar district (2.7–13.9 BqL-1), India.
|Figure 3: Variation of average radon concentration in different locations of study region|
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|Table 1: Average radon concentration and their respective annual effective dose of study region|
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As of now, the 222Rn activity level in drinking water is not regulated. Be that it may, the Safe Drinking Water Act directs the United States Environmental Protection Agency (USEPA) to propose and gave the Maximum Contaminant Level (MCL) for 222Rn in drinking water and furthermore to make accessible a higher Alternative MCL accompanied to address 222Rn hazard in indoor air. The proposed EPA's MCL is 11.1 BqL-1 (or 11.1 kBqm-3). In opposed to this, the European Union (EU) Commission issued a nonbinding recommendation in 2001 on the assurance of the general populace against exposure to 222Rn in drinking water supplies (2001/928/Erratum). Accordingly, it prescribes an action/reference level of 100 BqL-1 for public or commercial drinking water supplies and 1000 BqL-1 for individual or private water supplies. Remedial action is constantly justified/supported for water supplies with radon over 1000 BqL-1. Even the WHO has prescribed a treatment level of 100 BqL-1 for radon in drinking water supplies.
The radon level in the study area can be reduced by taking some short-term steps. For both adults and children, most exposure to radon comes from being indoors in homes, offices, schools, and other buildings. The general steps are to seal cracks and holes found in walls, floors, drains and pipes. Renovate existing basement floors, particularly earth floors. Increase ventilation in the subfloors beneath the basement. Install a device that sucks the radon from the lowest space in the basement (radon sump system). Avoid using exhaust fans for a continuous amount of time. When you are not using the fireplace, shut the chimney damper. By using these steps, we can help to minimize radon in our daily life.
[Table 2] gives minimum, maximum, and means radon activity concentration in different regions of the India and neighboring country Pakistan for comparison purposes. When the results of the present study are compared with North and South regions, the 222Rn level in these parts of the region are more prominent than studied region because of various factors such as geological structure, presence of fault, thorium rich soils, and granite rocks. While, in east and west regions, the 222Rn concentration from these areas are relatively comparable to the examined region. The average 222Rn concentration increases as one move from Amritsar (Punjab) to J and K Himalayas, i.e., from Punjab plains toward Siwalik Himalayas., It is well established that Himalaya's waterways and streams which charge underground water table in Punjab, contain peculiar level of 222Rn concentration. The presence of 222Rn in ground water is reasonably identified with the uranium content of the bedrock sand it can easily without much of a stretch go into the interfacing ground water by the impact of lithostatic pressure., The relatively higher estimation of 222Rn level in Amritsar city, though the level itself is very low, might be associated to fluctuating uranium level in drinking water detailed by Singh et al. (2003). The average of 222Rn activity level in ground water of Amritsar province were well inside as far as possible recommended by the USEPA and European Commission, and hence it. The acquired estimations are likewise not as much as the Islamabad and Peshawar region of the Pakistan [Table 2].
|Table 2: A literature review of radon concentration in drinking water of different regions and the neighboring country of the study area|
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Annual effective dose
The AED due to ingestion and inhalation per person was also evaluated in this study. The values of the AED per person caused by different water samples in this study are shown in [Table 1]. The average AED from ingestion of radon in drinking water was 1.24 μSvY-1 and that of inhalation of water-borne radon was 14.94 μSvY-1. Hence, the AED due to inhalation of water-borne radon was higher than those from radon ingestion from water [Figure 4]. As normally expected for any radionuclide associated with internal hazard, the dose due to inhalation of radon is higher as compared to ingestion. The estimated total AED ranged from 6.17 to 37.40 μSvY-1. The value of skewness and kurtosis for total AED is almost same as mean radon concentration. This means the distribution curve for total AED will be lognormal distribution. The measured values of AED per person were found to be well below the recommended limit of 100 μSvY-1 suggested by the WHO. The results of the present investigation will be helpful in the future for mapping the radon concentration in the different regions of Punjab, India.
Annual effective dose to the internal organs of the body
As 222Rn gas being an unpredictable gas, somewhat solvent in water, tends to leave the water upon contact with air. The rate of 222Rn exchange from water to air increases with temperature, agitation, mixing, and surface area. In domestic water usage, all gives sufficient air circulation to discharge a high level of the ground water's 222Rn content into indoor environment. Radon in water is likewise a source of radiation dose to various body organs such as lungs, stomach, colon, gonads, kidneys, liver, and skin, respectively, as it can enter the human body via ingestion and through inhalation. Hence, an attempt has been made in the present study to illustrate the radiation dose received by different body organs. The AED values received by lungs due to ingestion of waterborne radon varied from 0.92 to 5.61 μSvY-1 with the mean value of 2.49 ± 0.79 μSvY-1 for the groundwater samples [Table 3]. The average dose received by stomach and colon due to ingestion of radon contaminated water was 1.99 ± 0.76 μSvY-1. The average dose received by gonads, kidney, and skin due to ingestion of water containing radon was 3.32 ± 1.28 μSvY-1, 0.83 ± 0.32 μSvY-1 and 0.17 ± 0.06 μSvY-1, respectively [Figure 5]. It is obvious that the dose received by lungs and kidneys was on higher side [Table 3] when contrasted with the dose received by stomach, colon, gonads, liver, and skin. The total dose due to all organs was found well within the recommended limit (100 μSvY-1) suggested by WHO and ICRP.,
|Figure 5: Variation of average annual effective dose to different body organs|
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|Table 3: An annual effective dose for different body organs due to intake of radon in water samples of study region|
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| Conclusions|| |
The present investigation shows that the 222Rn concentration level in the majority part of the groundwater from the examined areas was not as much as the EPA's MCL value and WHO/EU's reference level. However, the overall AED coming from 222Rn emanating from ground-water were increasing with the increase in 222Rn activity level, but were although lower than the prescribed range of UNSCEAR and WHO. AED rate got by bronchial epithelium because of inhalation of water-borne 222Rn in air was fundamentally high over that of stomach walls through ingestion. The hazard due to 222Rn in water (which is commonly low) contrasted with total inhaled 222Rn is as yet remarkable because exposure occurs by both consumption of dissolved gas and inhalation of released 222Rn and its radioactive decay products from water, and hence not diminished. Consequently, it is better to take the measures to diminish concentration of 222Rn in drinking water, and thus, mitigation processes of reducing 222Rn gas related exposure in the public and working environments such as increasing indoor ventilation rate (open windows and air-to-air heat exchangers), expelling 222Rn decay products from the air (filters and fans) or ventilating the soil encompassing the building ought to be supported. Since, the way toward boiling of water additionally sets free the 222Rn gas from the water into the air, there ought to be no apprehensions about a radiation dose from drinking coffee or tea. However, it is critical to ensure that boiling takes place in well-ventilated areas to minimize the risks of inhaling 222Rn gas. Finally, screening of important radiological and in addition geographical parameters in high 222Rn activity concentration area in Amritsar province, specifically, and Punjab state, India by and large is likewise prescribed as it might be direct results of the spillage of high activity underground 222Rn and furthermore may be high utilization of agrochemicals in fields.
The author(s) are thankful to Principal of DAV College, Amritsar for providing necessary facilities to carry out research work and also the residents of the study area for their cooperation during the field work.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]