Gross alpha, gross beta and Ra-226 activity concentrations in bottled mineral waters sold in Bangkok Metropolitan area and their committed effective dose

Abstract

The activity concentrations of gross alpha, gross beta, and Ra-226 in some bottled mineral water samples sold in Bangkok Metropolitan area were measured from the view point of internal radiation for Thai consumers. Concentration ranges of gross alpha, gross beta, and Ra-226 in imported bottled mineral, domestic bottled mineral, and domestic bottled drinking water were as follows; for gross alpha, N.D. to 0.09, N.D. to 0.58, and N.D. to 0.17 Bq.l-1; for gross beta, N.D. to 0.44, N.D. to 0.45, and N.D. to 0.19 Bq.l-1; for Ra-226, 0.51 to 5.919, 0.422 to 9.915, and 0.096 to 0.398 mBq.l-1, respectively. On average, brands of domestic bottled mineral water contained the highest Ra-226 activity concentrations compared to those of imported bottled mineral and domestic bottled drinking water. However, all samples contained Ra-226 at concentration lower than the regulation limit for drinking water regulated by Thai Industrial Standard Institute (TISI), World Health Organization (WHO) and US. Environmental Protection Agency (US.EPA). The annual effective dose from intake of Ra-226 in waters to Thai different age groups (<1-17 y of age, and adults) was estimated. Group of infants and teens (10-17 y of age) child received the highest dose compared to all age group from the intake of Ra-226 in domestic bottled mineral water. These doses were approximately 25 times of that from intake of Ra-226 in domestic bottled drinking water and corresponded to 5.67-17% of the annual human exposure to radiation from water consumption (100 μSv) recommended by UNSCEAR (UNSCEAR 1993). Thus even though mineral waters contain useful elements needed especially during the period of maximum growth and development they can increase the risk of high exposures to human body due to ingest of Ra-226. Based on this study, while consumption is not a severe problem now, quality inspection of drinking water should be continued.

Key words : Gross alpha, gross beta, Ra-226, bottled mineral waters, committed effective dose