Risk assessment of heavy metals and pharmaceutically active compounds in river water from the central region of Peru

• The main sources of contamination of pharmaceuticals in surface waters could be livestock activities. • The hazard ratios for metformin were <1. • Carbamazepine, caffeine, copper and arsenic exceed the established safety thresholds. • Copper in the Mantaro River recorded a maximum apical HQ of 2.015 and suggests a potential significant adverse impact on aquatic biota. • Caffeine and nicotine in the Shullcas River revealed a higher potential risk, with apical HQs of 0.3459 and 0.1247, respectively. Pharmaceutically active compounds (PhACs) and heavy metals can be released from various sources into water bodies and cause water contamination and possible damage to aquatic biota. This study evaluated the risk of heavy metals and PhACs in river water from the central region of Peru. Water samples were collected from the upper, middle and lower reaches of the Mantaro, Chia, Cunas, Shullcas and Miraflores rivers, according to the method of analysis. The highest levels of most PhACs, including caffeine (4.15e + 03 ng/L) and acetaminophen (2.64e + 03 ng/L) were recorded at the Shullcas River. The level of arsenic (1.50e–02 mg/L) in the Mantaro River and zinc (1.36e–01 mg/L) in the Shullcas exceeded the safety limits for drinking water (0.01 mg/L and 3.0 mg/L, respectively). Apical hazard ratings (HQ) indicated potential risks. Nicotine and caffeine in the Shullcas River reached maximum HQs of 0.1247 and 0.3459, respectively. Copper represented the highest risk among heavy metals, with a maximum HQ of 2.015 in the Mantaro River. Cluster analysis grouped PhACs, and heavy metals and principal component analysis (PCA) differentiated ecotoxicological effects on organisms and rivers. The detection of elevated concentrations of carbamazepine, caffeine, copper and arsenic, exceeding safety thresholds, underscores the urgent need to improve water resource management practices in the region. Therefore, the high apical HQ values in these rivers suggest a significant risk to aquatic biota, especially to sensitive species such as crustaceans and fish. The detection of elevated concentrations of carbamazepine, caffeine, copper and arsenic, which exceed safety thresholds, underscores the urgent need to improve water resource management practices in the region. Therefore, the high apical HQ values in these rivers suggest a significant risk to aquatic biota, especially to sensitive species such as crustaceans and fish.