Sunlight exposure–driven changes in heavy metals and organic pollutants in bottled water: implications for Human Health in Nigeria

This study evaluated the migration of heavy metals and organic pollutants in Polyethylene Terephthalate (PET) bottled drinking water under heat exposure and withdrawal conditions. Heavy metals (Pb, As, Cd, Cr, Mn) were quantified using flame atomic absorption spectrophotometry. At the same time, dioxins (PCDD/PCDF) and 16 USEPA priority Polycyclic Aromatic Hydrocarbons (PAHs) were analyzed via Gas Chromatography–Tandem Mass Spectrometry (GC-MS/MS). Quality Assurance and Quality Control (QA/QC) included National Institute of Standards and Technology (NIST)-certified reference materials and isotopically labeled standards. Heat-exposed bottles showed increased metal levels, with Pb (1.84 µg/L) and Cr (1.27 µg/L) recording the highest mean concentrations. Benzo(a)pyrene (BaP), applied as an indicator for PAH contamination, was detected in 92% of exposed samples (mean: 0.038 µg/L). Dioxin toxicity equivalent values averaged 2.41 pg TEQ/L. USEPA risk estimates indicated that 37% of heat-exposed samples exceeded acceptable cancer risk thresholds, while hazard quotients highlighted notable non-cancer risk contributions from As and Mn. Pollutant occurrence was significantly associated with heat exposure (p < 0.05). The results underscore the influence of storage temperature on chemical leaching, supporting the need for improved regulatory monitoring and safer storage guidance to reduce chronic exposure risks.