A two-period survey of geothermal and groundwater sites in Kanchanaburi, conducted in November 2023 and November 2024, found that mercury and radium-226 at specific thermal sites exceeded Thai or WHO reference values. Modeled non-cancer risk in 2023 was driven by mercury; in 2024 it declined, while arsenic-related cancer risk at some locations remained above a commonly used risk-management level.
Key findings
- Mercury and Ra-226 exceeded reference values at selected sites. In 2023, the modeled total hazard index exceeded 1 and was driven mainly by mercury. In 2024, non-cancer risk declined, but arsenic-related modeled cancer risk at some sites exceeded 1×10−4, indicating spatial and temporal variability.
Why this matters globally
Geothermal waters worldwide support tourism, wellness, and local use. This study shows why one-time testing may be insufficient: geochemical conditions can vary, and oversight should consider both toxic metals and radionuclides.
Thai researcher contribution
Mahidol University researchers conducted field and risk analyses in Kanchanaburi, generating evidence that can guide site-specific monitoring and water-source management in Thailand.
Limitations to consider
Risk estimates were modeled for adult receptors rather than observed health outcomes and depend on exposure assumptions. Two sampling periods and selected locations cannot represent all sources or seasons. Users should rely on current local testing rather than this article for drinking-water decisions.