Modelling ecological risks of antiretroviral drugs in the environment

Abstract

The success of the antiretroviral therapy (ART) programme to manage HIV/AIDS in Sub-Saharan Africa (SSA) has inadvertently led to the release of antiretroviral (ARVs) into the environment. Consequently, ARVs have been detected in different countries across the globe, with the highest measured environmental concentrations in the SSA countries. Herein, we quantified ecological risks of ten regimen ARVs (six and four in first and second regimes, respectively) into environmental matrices in four spatial regions in Eswatini, namely: Manzini, Hhohho, Lubombo, and Shiselweni. Ecological risks (expressed as risk quotient (RQ)) were determined for different geographical regions by comparing the predicted environmental concentrations (PECs) to the predicted no effect concentrations (PNECs). PNECs were derived from ecotoxicological data generated using the Ecological Structure Activity Relationships (ECOSAR) model. PECs of ARVs in surfacewater in the Lubombo and Shiselweni regions were three-fold higher compared to those of the Manzini and Hhohho regions with RQs of three ARVs exceeding 10 (RQ > 10) to three taxa (fish, daphnia, and algae). ARVs of concern to the three taxa were ranked in descending order based on both acute and chronic toxicity based on RQ values as efavirenz (EFV) > lopinavir (LPV) > ritonavir (RTV) (all with RQs > 10). Two second regime ARV drugs (RTV and LPV) posed the highest risks to aquatic taxa though they had the least PECs, but were highly toxic with PNECs <1 μg/L. Due to dearth of toxicity data for ARVs on bacteria, their risks in wastewater (with the exception of TDF) could not be established. Results of this study are the first to quantify risks of ARVs in the environment using a modelling approach. The developed model can therefore serve as a first-tier screening tool. In addition, the results raise the need to examine the likelihood of antiviral resistance of ARVs linked to their high environmental concentrations.