Endocrine disrupting effects of HIV antiretrovirals in the South African aquatic environment

Abstract

The presence of endocrine disrupting chemicals (EDCs) in the environment is a growing concern as they pose potential risks to human and environmental health. These compounds interfere with natural homeostasis in living organisms, and have been reported to influence reproductive, endocrine and nervous systems of wildlife and humans. Due to the high prevalence of people living with the human immunodeficiency virus (HIV) in South Africa, as well as the subsequent high usage of antiretrovirals (ARVs) to treat this disease, these compounds are likely to end up in the environment. Wastewater treatment plants (WWTPs) are a major contributor of pharmaceuticals into surface water, and it has been found previously that ARVs are present in effluent intended to be released into receiving waters. The effects of these compounds on non-target organisms, such as aquatic species that spend a large portion of their life in direct contact with contaminated water, are largely unknown. These ARVs can have possible endocrine disrupting effects, but as of yet there are few studies done to determine this. The aryl hydrocarbon receptor (AhR) is responsible for metabolising xenobiotics from the environment and can bind to a wide variety of structurally diverse compounds from high to low affinity. Activation of the AhR can also cause possible endocrine disruption as it is involved in cross-talk with the oestrogen receptor (ER), acting as an antagonist. The aim of this study was to determine the concentrations of ARVs (efavirenz, lopinavir, ritonavir, nevirapine, zidovudine and didanosine) in surface water receiving WWTP effluent through instrumental analysis and to determine their possible biological response by using the H4IIE-luc reporter gene bioassay. The H4IIE-luc cells have been genetically modified to express the firefly luciferase enzyme in response to AhR activation as a result of CYP1A1 transcription. Seven WWTPs were chosen in the Gauteng province, and samples were collected upstream and downstream of the effluent release point. ARVs were quantified at 17 of the 20 surface water samples, varying in concentrations and detection frequencies. Efavirenz and lopinavir were found at the highest concentrations across the study. These two compounds were also the highest concentration found in South Africa for surface water, when compared with other studies. The WWTP are a point source for ARVs (and pharmaceuticals as a whole) in receiving waters. The water samples had no AhR-mediated activity, despite the high levels of ARVs present at some sites. The ARVs are thus unlikely to bind to the AhR and influence the ER through receptor cross-talk. These compounds will not have any endocrine disrupting effects through this pathway.