Incorporating a Screening-Level Risk Quotient (RQ_screen) for Assessing Human Health Risk of Pharmaceutical Residues in Consumption Water

Pharmaceutical residues are increasingly detected in aquatic environments and are recognized as contaminants of emerging concern. This systematic literature review compiled and evaluated published concentrations of pharmaceutical residues in bottled water, tap water, and surface water in Portugal, applying risk quotient (RQ) and screening-level risk quotient (RQ_screen) approaches to evaluate potential human health risks and prioritize contaminants. Assessment based on the compiled literature data across age groups showed bottled and tap water posed low risk, while surface water presented the highest concern, with compounds spanning the full risk spectrum. Key contributors to potential human health risk included hormones (17-alpha-ethinylestradiol, 17-beta-estradiol, estrone), ramipril, betamethasone, citalopram, and amoxicillin. RQ_screen highlighted compounds relevant for ongoing monitoring even in treated waters, such as carbamazepine, diclofenac, salicylic acid, warfarin, fluoxetine, and erythromycin, due to their persistence and toxicological significance. Both RQ and RQ_screen indicated higher risk values for infants and children, reflecting lower body weight and higher water intake per unit mass, underscoring the need for age-specific evaluations. The RQ_screen method proved useful for contaminant prioritization, identifying substances relevant for monitoring despite low concentrations. Overall, this systematic review highlights pharmaceutical residues as an emerging public and environmental health concern in Portugal and emphasizes the importance of targeted monitoring and risk-based management within a One Health framework.