Probabilistic health risk assessment of BTEX contamination in groundwater using the set of triplets methodology: a case study near Shiraz Oil Refinery, Iran

Groundwater contamination by petrochemicals, particularly benzene, toluene, ethylbenzene, and xylene (BTEX), poses a significant environmental and public health challenge. This study aims to provide a comprehensive probabilistic total health risk (THR) assessment for BTEX contamination, leveraging the ‘set of triplets’ methodology to improve risk evaluation accuracy and address the inherent uncertainties in contaminant transport as well as exposure. The approach integrates MODFLOW and MT3D-USGS models to simulate groundwater flow and BTEX transport dynamics. To manage uncertainties associated with exposure and toxicity, Monte Carlo simulations and Latin Hypercube Sampling were employed, allowing for robust scenario analysis. The ‘set of triplets’ framework—comprising scenario identification, probability estimation, and consequence evaluation—provides a systematic and precise method for quantifying health risks in complex subsurface environments. The results revealed medium to high-risk levels in several wells. In one area, the probability of the THR being below 0.06 was 0.01, while in another area, the probability of the THR being below 0.04 was the same. Furthermore, there is a significant probability (0.36 and 0.31) of exceeding the THR threshold of 10^− 6 in more than 50% of scenarios. This study offers several key advancements over prior research. The application of the ‘set of triplets’ methodology enables a more comprehensive management of uncertainties in risk assessments, providing deeper insights into the probability and impact of various contamination scenarios. Additionally, the integration of energy-efficient remediation strategies makes this research particularly relevant for regions facing limited water and energy resources. The advanced modeling techniques applied in this study allow for more accurate predictions of contaminant behavior in groundwater systems, offering critical guidance for environmental policymakers and risk management professionals.