Human health and ecological impacts of pharmaceuticals and metals released by municipal wastewater in Tehran: a life cycle impact assessment

Pharmaceuticals and metals in municipal wastewater pose significant risks to human and environmental health, necessitating further investigation due to their increasing use and limited data. This study assessed the impacts of commonly prescribed pharmaceuticals and metals in Tehran's municipal wastewater using the USEtox™ model, which quantifies chemical toxicity by integrating fate, exposure, and effect factors. In Tehran, Iran, 61% of untreated wastewater is released into watercourses, while 39% is treated by an activated sludge system and partially reused for agriculture. Target pharmaceuticals and metals were detected in both untreated and treated wastewater, with detection frequencies ranging from 33% to 100% for pharmaceuticals and 50% to 100% for metals. Acetaminophen (7.7 µg/L) and zinc (88.4 µg/L) had the highest concentrations in untreated wastewater, while citalopram (0.4 µg/L) and zinc (55.1 µg/L) dominated in treated wastewater. The lowest concentrations were for alprazolam, vanadium, and beryllium, ranging from 2 to 100 ng/L. The estimated health burden of pharmaceuticals and metals, based on ingestion risk and measured in disability-adjusted life year (DALY) per 100,000 people, was 0.03 for pharmaceuticals and 33 for metals, indicating years of healthy life lost due to illness or death. The environmental impact, measured by the potentially disappeared fraction (PDF) of species, reached 7.4E+06 (PDF.m³/year) for pharmaceuticals and 1.4E+09 (PDF.m³/year) for metals, indicating a significant loss of biodiversity. Sertraline and cadmium posed the greatest risks to human health, while thioridazine and cadmium was found to be most detrimental to ecosystems. These findings underscore the urgent need for improved wastewater management and further research into high-risk micropollutants.