Wastewater treatment processes cannot remove the bioactive compounds, underlining the need for technological advancements. Photo: Delwyn Verasamy
The presence of anti-retroviral (ARV) residues in drinking water may be “harmless” —prolonged exposure to the broader population may lead to antimicrobial resistance, said the Water Research Commission (WRC) and the department of water and sanitation.
Last week, the Mail & Guardian reported on a study by North-West University, which found that significant concentrations of ARVs have been detected in South Africa’s water sources, particularly downstream of wastewater treatment plants.
Current wastewater treatment processes are inadequate for removing these bioactive compounds, underlining the need for technological advancements, the authors said.
The drugs most frequently detected were lopinavir and efavirenz, with concentrations at some sites far exceeding global norms. South Africa has the most extensive HIV treatment programme of its kind in the world.
Aquatic ecosystems and wastewater management systems were affected. Freshwater snails exposed to ARVs exhibited altered embryonic development, while bacteriophages — viruses critical to controlling bacteria in wastewater treatment — were significantly affected. Such disruptions could lead to bacterial blooms and reduced water quality, the authors said.
“The consumption of any type of exogenous drug by any organism in sufficient quantities may intervene with the regulation of metabolic systems and bring about adverse effects,” said the study, warning that the presence of antiretrovirals in water “can be considered a hidden or latent risk”.
“Humans are also exposed to these compounds via drinking water, and at concentrations exceeding calculated hazard quotients,” the authors said. “Although not found in this study, humans and other organisms may potentially ingest antiretrovirals and their breakdown products via aquatic organisms such as fish.”
Concentrations of ARVs in some water sources exceeded acceptable thresholds, posing potential long-term health risks to people.
Nearly all antiretrovirals were found in natural systems and some in drinking water, although none were found in the fish tissue samples, nor were antiretroviral metabolites found.
Since early 2000, the WRC, along with local and international partner research organisations, has commissioned several studies on the presence of contaminants of emerging concern (CEC) in water resources and drinking water.
Its research has focused on CECs such as microplastics, chemicals, and pharmaceuticals that could potentially pose risks to human health and the environment. These studies inform the water quality guidelines and regulations issued by the department.
One of the studies related to ARVs was undertaken by the University of North West. “As reported in the media, the study found traces of ARVs in water samples taken from rivers and potable water sources, the joint statement said.
“This can be attributed to the pharmacological process where the active part of the medication is absorbed by the body, leaving the residual to be discharged from the body, subsequently finding its way into the sewage system. These traces of ARVs can then also be present in water that has been extracted from the rivers by municipalities to be treated and supplied as potable water.”
Globally, CECs are increasingly recognised as a concern for water quality, especially in wastewater and reclaimed wastewater for potable reuse, as well as agricultural water uses.
“However, CECs are a relatively new area of research globally, particularly relating to the causes and effects of CEC, the human health risks, treatment methods to remove CECs, and potential regulatory measures that can be taken to address the problem.”
The WRC research has focused on increasing understanding of the sources, pathways, and potential effects of CECs on water resources.
The South African National Standard SANS241 for water quality is based on World Health Organisation standards, ensuring that the human health risks are mitigated, said the statement. This has enabled the department to implement the blue and green drop programmes to provide information to the public on the performance of municipal water and wastewater systems relative to SANS241.
“The traces of pharmaceuticals, microplastics and other such CECs that have been found in water resources in South Africa are very small quantities, measured in nanograms (one billionth of a gram). Conventional water and wastewater treatment technologies are designed to remove much larger contaminants such as particles of faeces and bacteria.”
Higher concentrations of traces of ARVs were found downstream of wastewater treatment plants, which means that the municipal wastewater treatment works are not removing them, “because most existing wastewater treatment works have not been designed to remove CECs.
“Low concentrations of ARVs were found in some of the drinking water samples. There is a possibility that high concentrations of ARVs in sewage or municipal wastewater might reduce the effectiveness of the wastewater treatment works in removing bacteria from the wastewater. Further research is required in this regard.”
The WRC and the department said that there is limited knowledge of environmental toxicity, potential adverse effects on ecosystems and viral resistance of these compounds. “CECs in water is a growing global problem and area of attention around the world.
“Globally, the level of CEC compounds in water is generally not yet regulated. This is partly due to their presence often being below water quality detection limits. However, due to their continuous production, lack of appropriate disposal, constant input into the environment and presence in water resources, albeit in small concentrations, there is now increasing global research into the issue.”
Rand Water said it has been monitoring ARVs since 2015. “Rand Water, like other research institutions, detected ARVs in the natural waters located downstream of wastewater treatment plants.”
The bulk water services provider abstracts water from the Vaal Dam, which is located upstream of these wastewater treatment plants. “Rand Water has not detected ARVs at the point of abstraction in the Vaal Dam and concomitantly in any of its treated final drinking water.”
“Rand Water assures the public that drinking water remains safe for human consumption.
Rand Water, as the remains committed to protecting the health of consumers by providing potable water that complies with SANS241 standards and safe for human consumption.”
For the study, North-West University sampled water upstream and downstream of wastewater treatment plants — specifically Sunderland Ridge, Vlakplaats, Waterval, Olifantsfontein River, Welgedacht, Zeekoegat, Flip Human and Baragwanath — in northern and southern Gauteng. Sampling sites included the Jukskei, Hennops, Klip and Crocodile rivers. The Mooi River, which is close to Khutsong in North West and downstream of Wonderfonteinspruit in Gauteng, was also sampled.
The most frequently detected compound was fluconazole (28 detections from 72 samples), with concentrations ranging from 0.06 to 1.8 μg/L (micrograms per litre). Nevirapine and efavirenz were the second-most detected compounds, both with 22 out of 72 samples. On average, lopinavir and efavirenz had the highest concentrations of the compounds analysed. Didanosine and zidovudine were the least detected compounds — two and six out of 72.