Pyrethroids in groundwater near the Citarum River: Insights into ecological and health risks

While pyrethroid presence in rivers in Indonesia, particularly the Citarum River, has been reported, no studies have documented its occurrence in groundwater. This study is the first to report pyrethroid contamination in groundwater in Indonesia. We examine the distribution of pyrethroid concentrations in groundwater near the Citarum River in relation to distance from the river and evaluate the associated ecological and health risks. Of the nine pyrethroids tested, five were detected in Citarum River samples, and all were found in groundwater well samples, exceeding the maximum permissible concentration. Allethrin and β-cyfluthrin were detected in all water samples at concentrations of 101–264 ng/L and 12–58 ng/L, respectively. Although allethrin concentrations decreased with increasing distance from the river and increased with decreasing elevation, no significant correlation was found between distance, elevation, and allethrin concentrations. No distinct pattern was observed for β-cyfluthrin in river and groundwater samples. Additionally, neither allethrin nor β-cyfluthrin showed a significant correlation with proximity to agricultural areas, indicating that contamination sources may not be solely related to agricultural activities. Ecological risk assessment revealed that pyrethroid contamination poses a significant ecological threat to the Citarum River (Total Risk Quotient (TRQ) ≥ 1). However, total non-carcinogenic risk levels for pyrethroids in all groundwater samples were below 1, indicating no non-cancer health risks. These findings highlight the need for further research on pyrethroid dynamics and land-use interactions.