annual effective dose due to 222Rn in spring and some surface waters of Johor State Malaysia

Abstract

Ubiquitousnbiquitous nature, along with the detrimental health impact of radon (222R), has led to the

investigation of its activity concentration in the various environmental medium, including

bodies of water. This work was conducted to estimate the annual effective dose of inhalation

due to 222Rn in spring and some surface waters in Johor state, Malaysia. 222Rn activity

concentration was measured using RAD7 alpha detector. The annual effective dose for

inhalation was evaluated using the measured 222Rn activity concentration in water. The activity

concentration of 222Rn in water varies from 80 ± 110 to 5400 ± 1100 mBq l-1 in surface and

spring water respectively. The measured activity concentrations in the samples were found to

be below the EPA and WHO maximum permissible limit for 222Rn in Water of 1100 mBq l-1

and 105 mBq l-1 respectively. The highest value of 222Rn activity concentration was measured

in spring water discharging from granitic rocks Aquifer. While the lowest value was measured

in surface waters. The values of an annual effective dose of inhalation, due to 222Rn in spring

water, were found to range from 0.998 to 5.139 µS y-1 with a mean value of 2.15 µS y-1

, while

in the surface waters the values range from 0.076 to 1.140 µS y-1 with a mean value of 0.423

µS y-1

. The inhalation doses estimated were found to be well below the recommended limit set

by UNSCEAR of 1260 µ Sv y

–1

.