Concentration of perchlorate in drinking water: a global systematic review-meta-analysis and probabilistic human risk assessment

We searched Web of Science, Scopus, PubMed, and Embase (2000–2025) for studies reporting ClO4− levels in drinking water. Data on country, water source type, concentration (mean/SD), and analytical methods were extracted. A random-effects meta-analysis was performed to estimate pooled ClO4− concentrations. Non-carcinogenic risk was evaluated using the Hazard Quotient (HQ), with Monte Carlo simulation (MCS) model to account for uncertainties in exposure parameters (concentration, ingestion rate, body weight). The meta-analysis revealed significant regional variability, with the highest ClO4− concentrations in the United Arab Emirates (370.05 μg/L), Chile (96.82 μg/L), and India (80 μg/L), exceeding WHO and USEPA guidelines. Groundwater had substantially higher levels (pooled mean: 5.55 μg/L) than surface water (0.22 μg/L). Probabilistic risk assessment identified elevated HQ values ( >1) in the UAE (17.67), Chile (5.56), India (3.08), Namibia (2.55), and Japan (1.25), indicating potential thyroid disruption risks. In contrast, most European and East Asian countries showed negligible risk (HQ < 1). ClO4− contamination in drinking water poses significant health risks in regions with high industrial activity, arid climates, or natural geological deposits. Groundwater is particularly vulnerable due to prolonged accumulation. Regulatory measures, advanced treatment, and targeted monitoring are urgently needed in high-risk areas to mitigate exposure.