Persistent organic pollutants in India: Multi-compartment trends, source fingerprinting, and emerging environmental...

Persistent Organic Pollutants (POPs), particularly polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs), continue to persist in India's environment despite phased bans, restricted use, and national commitments under the Stockholm Convention. This review synthesizes 25 years (2000-2025) of POP research across groundwater, surface water, soils, and sediments using a PRISMA-guided screening approach, geochemical spatial integration, and a quality-weighted dataset. The objective is to consolidate evidence on environmental occurrence, dominant source pathways, analytical advancements, ecological and human-health risks, and regulatory gaps, and to establish a scientifically robust framework for long-term monitoring and risk-informed policy development in India. Available evidence indicates that POP contamination in India is highly heterogeneous and controlled by land-use intensity, industrial clustering, hydrogeological settings, and monsoon-driven hydrodynamics. Legacy OCPs, including DDTs, HCHs, aldrin, and endosulfan, remain prevalent in agricultural regions, while PAHs derived from vehicular emissions, biomass combustion, and industrial activities dominate urban and industrial centers. PCBs persist due to transformer oils, informal e-waste recycling, and thermal processes, with riverine and estuarine sediments acting as long-term sinks and secondary sources through resuspension, erosion, and bioturbation. Recent analytical advances, including microextraction techniques, MAE/ASE, high-resolution mass spectrometry, and molecular and isotopic fingerprinting, have improved detection sensitivity and source resolution. Receptor modeling approaches consistently reveal mixed pyrogenic-petrogenic signatures and ongoing unintentional emissions. Risk assessments indicate carcinogenic, endocrine disrupting, immunotoxic, and neurodevelopmental effects, with biomagnification evident in aquatic food webs. Major gaps persist in national monitoring coverage, methodological standardization, mixture-toxicity evaluation, and probabilistic risk assessment. Strengthening POP management in India requires coordinated monitoring networks, harmonized analytical protocols, open-access data systems, and alignment with global chemical governance frameworks.