South Africa’s waste- water treatment works are being burdened with increased rates of influents containing a large “cocktail” of chemical pollutants.
Dr Edward Archer, a post-doctoral fellow in the department of microbiology at Stellenbosch University, says this is unfolding as the country becomes more urbanised, with populations increasing exponentially.
“Recently, reports on the detection of pharmaceuticals in South African surface waters have increased tremendously, spanning a large list of pharmaceutical classes such as antibiotics, anti-epileptics, non- steroidal anti-inflammatory drugs, diabetes medications, antihistamines, opioids, illicit drugs and more.
“Many of these chemical pollutants have been associated, to some extent, with sub-lethal health effects in aquatic organisms, including endocrine and neuro-endocrine disruption at environmentally relevant concentrations as well as the potential development of antibiotic-resistant pathogens.”
Moreover, he points out, many of these pollutants persist throughout wastewater treatment and in the environment.
Such examples include the anti-epileptic drug carbamazepine, the anti-depressant drug venlafaxine, the analgesic tramadol and anti-inflammatory drugs such as diclofenac and naproxen.
“Although these organic compounds do break down to some extent during wastewater treatment processes and within the environment, the fate of their breakdown products (metabolites) are not well investigated, especially their eco-toxicological effects.
“Many pharmaceutical products metabolise almost fully during administration, whereby their breakdown products are sometimes more physiologically active and excreted in sewage.”
A recent study by his research group and its partners found that mass load concentrations (grams of chemicals entering wastewater treatment plants) of some pharmaceutical metabolites (from carbamezepine, tramadol and venlafaxine) are even higher in wastewater and may be more difficult to remove during treatment than their parent compounds.
“It became evident that the environmental risk from such break-down products should receive even more priority. Also from this study, it was highlighted that we are dealing with the same types of micro-pollutants as other countries worldwide, possibly at elevated concentrations.”
He illustrates diclofenac as an example. “On the EU watchlist of emerging contaminants, the concentration of diclofenac in surface waters has been proposed to not exceed 100 nanograms per litre of water.
“In various monitoring studies of South African surface waters, diclofenac has been detected at concentrations ranging from 300 nanograms to 15600 nanograms per litre in environmental waters.
“In treated wastewater discharge, these concentrations may even surpass the 100 micrograms per litre level, 1000 times more than the proposed EU limit.”
Even developed countries face the problem of micropollutants that persist throughout their advanced treatment processes, he says.
While South Africa has made improvements in advanced physical, chemical and microbial treatment technologies and improved treatment capacities, these advances are reliant on large funds to construct, maintain and manage, which cannot always be met.
“The lowering of harmful chemical pollutants in our environment can therefore start with the consumer, such as avoiding improper disposal of expired pharmaceuticals and unwanted household chemicals, avoiding unnecessary prescriptions and over-the-counter medications and familiarising themselves with harmful compounds which are present in certain consumer products.”
This week, researchers from the IHE Delft Institute for Water Education in the Netherlands revealed how they had identified global hotspots of highly concentrated pharmaceuticals in rivers and lakes, using data from a global database of anti-inflammatory diclofenac consumption and occurrence in freshwaters.
Presenting research on the fate of pharmaceuticals in freshwater at the European Geosciences Union general assembly, the researchers found that if no mitigating action was taken, the environmental threat from pharmaceuticals would soar by 65% in 2050.
Pollution levels are likely to be substantially higher in much of Latin America, Africa and Asia where less than a quarter of wastewater is treated and with technology unable to filter out most pharmaceuticals.
“We found out that technological improvements alone will not even be enough to recover from the current concentration levels. If a substantial consumption reduction is not implemented, a large part of the global river ecosystems will not be sufficiently secured,” researcher Francesco Bregoli told the assembly.
Archer, who together with his colleagues has conducted extensive research on the issue, says South Africa is no exception to the global challenge of increased contamination of freshwater ecosystems by organic chemical pollutants.
“In particular, pharmaceutical and personal care products are ubiquitous in any populated region during modern times to improve and maintain human health and well-being.”
Rand Water and the Department of Environmental Affairs referred queries to the Department of Water and Sanitation (DWS), which did not respond this week.
A policy document issued by DWS last year noted that far more research was needed in emerging contaminants “to avoid the introduction of potentially harmful new pollutants into our water resources”.
“Pharmaceuticals in the water have become a significant challenge in Africa and South Africa and more research is needed on the potential health impact of these chemicals on the environment and specifically on human health,” says Tiaan De Jager, a professor of environmental health at the school of health systems and public health at the University of Pretoria.
Many emerging contaminants, including pharmaceuticals, have endocrine disruptive properties.
“There are a number of known sources of endocrine-disrupting chemicals and other hazardous chemicals in Africa.
“However, a co-ordinated approach to identify and monitor these contaminants and to develop strategies for public health interventions has not yet been made.”