Annual Effective Doses Due to Radon in Consumer Water Supplies in the Phuphi and Khao Niphan Mining Areas, Surat Thani Province, Southern Thailand

Phattharasuda  Rodprapai; Sutthini  Aiedsittirak; Supasuta  Yamsang; Parichat Srinin; Napatsawan Muengjan; Apisara Sikhwankaeo; Sumit  Jirungnimitsakul; Kotchakorn Pengsri; Kanokkan Titipornpun

Phattharasuda Rodprapai Suratthani Rajabhat University
Sutthini Aiedsittirak Suratthani Rajabhat University
Supasuta Yamsang Suratthani Rajabhat University
Parichat Srinin Suratthani Rajabhat University
Napatsawan Muengjan Suratthani Rajabhat University
Apisara Sikhwankaeo Suratthani Rajabhat University
Sumit Jirungnimitsakul Suratthani Rajabhat University
Kotchakorn Pengsri Suratthani Rajabhat University
Kanokkan Titipornpun Suratthani Rajabhat University

Keywords: radon in water, annual effective dose, mining area

Abstract

In Ban Na San District and Wiang Sa District of Surat Thani Province, gypsum and anhydrite are mined. This area also has a relatively high surface concentration of uranium, directly impacting radon gas levels in the environment, particularly in water sources for consumption, potentially causing health risks. Therefore, this research aims to study the physical characteristics of water, measure the concentration of radon gas in water, and evaluate the annual effective doses from radon due to ingestion and inhalation from water sources used for consumption around the Phuphi mining area in Ban Na San District and Khao Niphan in Wiang Sa District, Surat Thani Province. A total of 30 water samples were obtained from tap water, groundwater, canal water, and mine well water. The research results found that the average temperature, pH, electrical conductivity, dissolved solids, salinity, dissolved oxygen, and background radiation doses were at levels of 30.2±0.9 °C, 6.21±0.93, 0.06±0.07 S/m, 0.31±0.37 g/L, 0.31±0.37 ppt, 7.60±0.12 mg/L, and 1.2±0.3 mSv/y, respectively. The concentration of radon gas in water ranged from 5.54±1.02 Bq/L to 53.79±3.62 Bq/L, with an overall mean value of 27.74±14.51 Bq/L, exceeding the U.S. EPA standard limit for radon contamination in drinking water (11.1 Bq/L). When comparing the average radon gas concentration, the Phuphi mining area had 31.69±15.82 Bq/L, while Khao Niphan had 23.79±12.33 Bq/L. It was found that there was no statistically significant difference at the 0.05 level. Additionally, the mean radon gas concentration in groundwater (45.90±6.35 Bq/L) was higher than in canal water (33.34±12.09 Bq/L), tap water (26.36±5.28 Bq/L), and mine well water (6.64±0.70 Bq/L), respectively. The evaluation of the total annual radiation dose from ingestion and inhalation showed an average of 75.73±39.60 μSv/y, which is lower than the WHO recommended reference level of 100 μSv/y. However, the average annual exposure to radiation from ingestion and inhalation of groundwater (125.31±17.33 μSv/y) was found to be higher than the reference level. Despite other water sources having values below the reference level, it is recommended not to drink water directly from these sources in the study area without standard treatment for drinking water.