Browsing by Author "Tokonami, Shinji"

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A Study Into the Long-Overlooked Carcinogenic Radon in Bottled Water and Deep Well Water in Dhaka, Bangladesh
(Taylor & Francis Group, 2023-01-10) Mahmud, Jubaier Al; Siraz, M. M. Mahfuz; Alam, Mohammad Shafiqul; Das, Sudeb Chandra; Bradley, David Andrew; Khandaker, Mayeen Uddin; Tokonami, Shinji; Shelley, Afroza; Yeasmin, Selina
Radon (222Rn), a radioactive and gaseous progeny of Uranium (238U) decay series, accounts for almost 50% of the total background radiation in our dwelling environment. Inhalation and ingestion of radon in excessive amounts pose serious health effects to humans. The first-ever measurement of radon concentration in commercial bottled water available in Dhaka city and deep well water samples from the campus of the University of Dhaka was carried out using the RAD7 Radon monitoring system. The concentration of radon in the bottled water ranged from 0.11 Bq/L to 1.30 Bq/L with a mean of 0.59 Bq/L, and the deep well water showed a mean of 4.88 Bq/L with a range of 3.02 Bq/L to 5.98 Bq/L. All twenty-five samples of water had radon concentrations within the recommended limits of USEPA and WHO. The mean annual effective doses from radon in bottled water and deep well water were evaluated to be 0.126 µSv/y and 12.481 µSv/y, respectively. Although the calculated doses indicate the least potential risk according to WHO and UNSCEAR, however, it is expected that the present results play an important role in setting up a national guideline for radon in drinking water, and the monitoring of radon for the safety of public health.
A Study on Measuring the 222Rn in the Buriganga River and Tap Water of the Megacity Dhaka
(PLOS ONE, 2023-05-23) Alam, M. S.; Siraz, M. M. Mahfuz; A. M., Jubair; Das, S. C.; Bradley, D. A.; Khandaker, Mayeen Uddin; Tokonami, Shinji; Shelley, Afroza; Yeasmin, Selina
Radon (222Rn), an inert gas, is considered a silent killer due to its carcinogenic characteristics. Dhaka city is situated on the banks of the Buriganga River, which is regarded as the lifeline of Dhaka city because it serves as a significant source of the city’s water supply for domestic and industrial purposes. Thirty water samples (10 tap water from Dhaka city and 20 surface samples from the Buriganga River) were collected and analyzed using a RAD H2O accessory for 222Rn concentration. The average 222Rn concentration in tap and river water was 1.54 ± 0.38 Bq/L and 0.68 ± 0.29 Bq/L, respectively. All the values were found below the maximum contamination limit (MCL) of 11.1 Bq/L set by the USEPA, the WHO-recommended safe limit of 100 Bq/L, and the UNSCEAR suggested range of 4–40 Bq/L. The mean values of the total annual effective doses due to inhalation and ingestion were calculated to be 9.77 μSv/y and 4.29 μSv/y for tap water and river water, respectively. Although all these values were well below the permissible limit of 100 μSv/y proposed by WHO, they cannot be neglected because of the hazardous nature of 222Rn, especially considering their entry to the human body via inhalation and ingestion pathways. The obtained data may serve as a reference for future 222Rn-related works.
The presence of carcinogenic radon in the Padma River water, adjacent to the Rooppur Nuclear Power Plant
(Daffodil International University, 2023) Siraz, M.M. Mahfuz; Alam, M.S.; A.M., Jubair; Das, , S.C.; Ferdous, J.; Hossain, Z.; Das, S.; Khandaker, Mayeen Uddin; Bradley, D.A.; Tokonami, Shinji; Yeasmin, S.
Radon is a naturally occurring carcinogenic agent, poses a serious health hazard when inhaled or ingested in significant amounts. The water of the Padma river will be used as a tertiary coolant for the soon-to-be-commissioned ‘Rooppur Nuclear Power Plant’. Hence, it is important to assess the radiological status of the river prior to the commission of this power plant. Therefore, for the first time, 25 samples of water were collected from various locations of the Padma River and analyzed for radon concentration using the RAD H2O (DURRIDGE) radon monitoring device. The radon concentrations were found in the range from 0.077 ± 0.036 to 0.494 ± 0.211 Bq/L with a mean of 0.250 ± 0.093 Bq/L. All the concentrations were found to be below the recommended limits of WHO (100 Bq/L) and USEPA (11.1 Bq/L). The mean annual effective dose due to the radon exposure via inhalation and ingestion pathways were 0.638 μSv/y and 0.629 μSv/y, respectively, which were all well below the annual effective dose recommended by WHO (0.1 mSv/y). Since Bangladesh lacks a national safety limit of radon in water, this pioneering study provides baseline data on radon levels for the environment around Rooppur Nuclear Power Plant.