Radiological Health Risk Assessment of Radon in Natural Hot Springs and Consumption Water in Phunphin and Khian Sa Districts, Surat Thani Province

Nutranich Titipornpun; Chaloamar Sangnil; Rakkan Senthong; Suratsawadee Nilkij; Apinun Titipornpun

Nutranich Titipornpun Suratpittaya School, Surat Thani
Chaloamar Sangnil Suratpittaya School, Surat Thani
Rakkan Senthong Suratpittaya School, Surat Thani
Suratsawadee Nilkij Suratpittaya School, Surat Thani
Apinun Titipornpun Suratpittaya School, Surat Thani

Keywords: Radon, annual effective doses, salt hot spring, RAD7-RAD H2O

Abstract

Radon is a radioactive element that naturally decays from sources containing uranium and radium in soil, rocks, and groundwater. In particular, fractured areas, such as natural hot springs, can exhibit high radon concentrations. Therefore, this work aimed to investigate the physicochemical characteristics and measure radon concentrations in natural hot spring water and consumption water. Additionally, this study evaluated the annual effective dose from radon exposure in natural hot springs for wellness tourism, specifically at the Tha Sathon Hot Spring in Phunphin District and the Khao Tok Hot Spring in Khian Sa District, Surat Thani Province. A total of 33 samples were analyzed, comprising natural hot spring water, tap water, and bottled drinking water. The results showed that the mean temperature was 37.42±11.66 °C, the mean pH was 7.21±0.49, the mean electrical conductivity (EC) was 0.08±0.06 S/m, the mean total dissolved solids (TDS) was 0.42±0.30 g/L, the mean salinity was 0.42±0.05 ppt, and the mean dissolved oxygen (DO) was 8.12±0.47 mg/L. The mean radon concentrations in the water within the study area ranged from $0.15±0.00 Bq/L to 119.47±24.12 Bq/L, with an overall average of 35.87±46.98 Bq/L. This overall average exceeded the Maximum Contaminant Level (MCL) for drinking water (11.1 Bq/L) defined by the US EPA but was lower than the WHO reference level (100 Bq/L). Additionally, the average radon concentration in hot springs (63.93±48.16 Bq/L) was significantly higher than that found in tap water (2.71±1.03 Bq/L) and bottled drinking water (0.15±0.00 Bq/L). The average background radiation dose in the study area was 3.29±2.58 mSv/y, which was higher than the global average (2.4± mSv/y). The estimated total annual effective dose from radon ingestion and inhalation in the study area averaged approximately 97.95±128.23 µSv/y. Regarding internal organ effects, the annual effective doses to the stomach and lungs were approximately 0.91±1.18 µSv/y and 10.85±14.21 µSv/y, respectively, which were below the WHO reference level (100 µSv/y). However, as numerous factors influence radon concentrations, further in-depth studies are recommended. Continuous monitoring and surveillance in the study area and other locations should also be conducted to better understand the actual radon risk and to ensure the safety and health of both residents and tourists.