Abstract:
Radon (222Rn) activity concentration in ground water, tap water, tube well and different branded bottled drinking water collected from different locations of Dhaka city is measured using both alpha particle spectrometry and gamma ray spectrometry systems. The results obtained from both techniques are in good agreement. The total annual effective dose for inhalation and ingestion, internal organ dose (lung and stomach), annual effective dose for different age groups (infant, children and adult) and excess life time cancer risk due to radon in water have also been evaluated. It is found that the 222Rn activity concentration in ground water of the investigated area of Dhaka city varies from 4.56±0.37to 15±2.33 Bq/L and the average value of 9.29±1.40Bq/L, tap water varies from 1.15±0.06 to 4.65±0.39 Bq/L and the average value of 2.47±0.47 Bq/L, tube well water varies from 2.73±0.67 to 3.89±1.01 Bq/L and the average value of 3.31±0.75Bq/L and bottled water varies from 0.12±0.04 to 0.82±0.08Bq/L and the average value of 0.32±0.11Bq/L. This study reveals that the 222Rn activity concentration in seven out of twenty-nine ground water samples is found higher than the allowed maximum contamination level for radon in drinking water proposed by United States Environmental Protection Agency. For all cases, the annual effective dose is found lower than the recommended level by World Health Organization and European Union. The probability of excess life time cancer risk for infant is higher than children and adult for all type of water consumption and for all age groups the excess life time cancer risk is highest for ground water.
