Presence, dynamics, and risk assessment of antiretrovirals in South African waters

Abstract

Environmental contamination of antiretroviral drugs (ARVDs) is an emerging concern in South Africa, because of the high number of individuals on antiretroviral therapy (ART) programs as well as lack of pharmaceutical effluent guidelines. The current study offers among the first national assessments of ARVDs in South African waters, revealing contamination in drinking water (0.1 ng/L-27 μg/L), groundwater (0.3-13 ng/L), surface water (0.1 ng/L-102 μg/L), and wastewater (0.3 ng/L-814 μg/L). The study applied a multidisciplinary approach combining literature review, site-specific monitoring, spatial and temporal analysis, ecological and human health hazard assessments, and hybrid mixture toxicity modelling, while accounting for analytical, regulatory, and exposure-related uncertainties. By integrating multiple exposure and hazard indicators into a weighted multi-criteria model, the study enabled evidence-based ranking of selected ARVD contaminants. Disparities in ARVD detection and removal highlight the insufficiency of existing wastewater treatment technologies. Spatial analysis identified contamination hotspots near wastewater treatment plant discharges, particularly in the Hennops, Klip, and Jukskei Rivers. Site-specific pollution patterns were primarily independent of seasonal variation, although efavirenz and ritonavir exhibited seasonal peaks. Hazard assessments demonstrated moderate to high ecological risks for both individual ARVDs and mixtures, with lopinavir, efavirenz, and zidovudine identified as critical pollutants. A mixture toxicity model combining concentration and response addition confirmed additive and independent toxic effects in wastewater and surface water. Several ARVDs exceeded non-carcinogenic hazard thresholds, posing significant toxic potential to vulnerable populations such as children and pregnant females. The weighted multi-criteria model identified abacavir, lopinavir, efavirenz, emtricitabine, and nevirapine as the highest-priority ARVDs due to their combined high environmental occurrence, toxicity, and potential for human and ecological risk. The findings emphasise the urgent need for improved treatment technologies, targeted monitoring of priority ARVDs, and adaptive regulatory frameworks that integrate scientific uncertainty and cumulative exposure risks. This study supports the implementation of eco-pharmacovigilance strategies, proactive policy interventions and a more health-protective regulatory landscape in the face of emerging pharmaceutical contaminants.