Glass of water half full of riskComment on this story
Johannesburg - Elevated levels of two potentially harmful herbicides have been detected in Joburg’s drinking water, while an anti-convulsant and mood-stabilising drug may taint Bloemfontein’s water supply.
This is according to an extensive national survey on the concentration of these top three emerging contaminants (ECs) in the drinking water of several of South Africa’s metropolitan areas, which the Water Research Commission released.
Professor Hugh G Patterton of the University of the Free State’s advanced biomolecular research cluster, set out to investigate and identify the most important new substances in drinking water quality “that could be a concern to human health in South Africa”.
He and his team detected 34 pharmaceuticals or pesticides, “demonstrating that a wide range of pharmaceuticals and pesticides were present in South Africa’s drinking water”.
Of most concern was the trio of potentially dangerous chemical compounds – herbicides atrazine and terbuthylazine, and mood stabiliser carbamazepine – which were detected in the highest number of samples and with the most number of seasonal occurrences.
Patterton notes in his study how atrazine posed a “medium risk” in the drinking water in Joburg, Bloemfontein, Durban and Pietermaritzburg.
Terbuthylazine, too, posed a medium risk in the drinking water from all seven sourced metropolitan areas, while carbamazepine posed a medium risk in the drinking water of Pretoria, Joburg, Bloemfontein, Durban and Pietermaritzburg.
“Although the levels of the three most frequently observed ECs were less than 10 percent (of the US and EU guidelines), the range of ECs observed may indicate a growing problem.
“We lack information on the vulnerability of populations and their capacity to overcome the proposed hazard.”
The study notes how there is no enforced testing scheme in the current SANS241-2011 specification to establish the presence or to determine the level of pesticides and pharmaceuticals that are considered as ECs. “There is also limited knowledge on the possible diverse health impacts of ECs.”
Patterton and his team repeatedly collected samples from water purification plants in Bloemfontein, Joburg, Pretoria, Durban, Pietermaritzburg, Port Elizabeth and Cape Town at points before the water entered the reticulation system.
In Bloemfontein, water was also collected from domestic taps.
Other compounds that were detected in three or more seasons included hexazinone, phenytoin and tebuthiuron in Durban and Joburg, and fluconazole, phenytoin and tebuthiuron in Bloemfontein.
The anti-malarial, cinchonidine, was found in at least three seasons in each of the seven cities.
Patterton recommends a national programme in which drinking water is seasonally or bi-annually qualitatively screened “to fully understand the possible impact of ECs on the SA water consumer”.
His report warns that there is no information on the presence of ECs in surface and groundwater.
“Their proximity to sites of intense agricultural activity or landfill, and medical-waste dumping sites, may cause the presence of very high levels of ECs in such water sources.
“The domestic use of water retrieved from rivers, dams and boreholes – often the norm in rural and farming communities – may expose humans to levels of ECs significantly higher than that detected in the purified water that is supplied to metropolitan areas.”
This may expose rural communities to high health risks.
The study also demonstrated the presence of “many other ECs, which, although they were present less frequently in the sampled water, have been associated with serious health effects, such as leukaemia”, and were also unregulated.
What are emerging contaminants (ECs)?
These are an extensive and increasing range of water contaminants, typically for which no regulatory guidelines exist. They include the partially overlapping groups of pharmaceuticals, pesticides, endocrine-disrupting compounds, cyanotoxins, personal-care products, industrial and manufacturing chemicals, and micro-organisms, including bacteria, viruses and parasites.