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‘Superbugs’ breed in City’s polluted waters

Children play at Zandvlei mouth as it runs out to sea at Muizenberg. The water has for months been too polluted for recreational use.
The ongoing and widespread pollution of Cape Town’s waterways is contributing to antibiotic resistance, which is a growing and serious global health problem, according to pre-eminent scientists.
The pollution is caused by sewage spills, human and chemical waste being discarded into the storm water system, and poorly treated effluent released from waste water treatment works.
It is well documented that pharmaceutical compounds, including antibiotics, are found in sewage.
As a result, bacteria exposed to low levels of antibiotics and other persistent chemical compounds, develop antibiotic resistance, leading to the emergence of ‘superbugs’.

Widespread pollution

For the first time in Cape Town’s history, all its popular recreational water bodies – Zandvlei, Rietvlei, Zeekoevlei, and the Milnerton Lagoon – have been closed for months due to ongoing pollution, largely related to chronic sewage inflows.

In the past, these water bodies have been individually closed for short periods due to temporary pollution incidents that pose a health risk for even intermediate contact use such as kayaking, sailing, and fishing, but never all of them together or for such an extended period.

Zandvlei at Muizenberg, plagued by numerous sewage spills resulting in temporary closures last year, was closed for recreational use on 25 May, having only been partially reopened on Friday 1 October.

Rietvlei near Milnerton, which in the past five years was only closed for a week in 2019 due to a toxic algal bloom, was closed to public use on 24 June due to water quality tests revealing e.coli – a bacteria indicating faeces in the water – being above the acceptable limit.

Ongoing sewage spills then resulted in Zeekoevlei being closed on 15 July. At the time of writing, all three of these water bodies remained closed.

Meanwhile, pollution of Milnerton Lagoon, which receives effluent from the Potsdam Waste Water Treatment Works, resulted in the Green Scorpions (the provincial environmental management inspectorate) issuing a directive to the City of Cape Town in November last year, ordering the City to clean it up.

The directive was appealed by the City but legal project manager at the Organisation Undoing Tax Abuse, Andrea Korff, says the City submitted their response to the Green Scorpions on 27 August. Korff said OUTA has requested sight of this response but have as yet to receive a copy.

Korff said last week the City stated they would receive feedback from the Green Scorpions in two weeks time.

Meanwhile, head of the Milnerton Central Residents Association environmental portfolio, Caroline Marx, said the City’s own tests showed “shockingly high” levels of e.coli in the lagoon.

She said as a result, the lagoon remains closed for recreational water users.

Drug resistance

In June, Mother City News reported on a recently published peer-reviewed scientific paper revealing the antibiotic Sulfamethoxazole is present in False Bay’s water. It, along with other pharmaceutical compounds, was present in the sediment, seaweed, and marine invertebrates such as mussels, limpets, sea snails, sea urchins, and starfish.

The study by scientists Cecilia Y. Ojemaye and Leslie Petrik from the University of the Western Cape’s Chemistry Department showed Sulfamethoxazole and other pharmaceutical compounds such as Diclofenac (Voltaren) were accumulating up the marine food chain.

The pharmaceutical compounds enter the environment from waste water, but waste water treatment technology does not remove these persistent chemical compounds which enter the waste stream due to their not being fully metabolised by users, or due to unused or expired medication being flushed into the sewerage system. Additionally, waste water from hospitals and clinics, highly likely to contain pharmaceutical compounds including antibiotics, flow to municipal waste water treatment works which often do not meet national minimum treatment guidelines for the removal of bacteria.

This results in bacteria such as e.coli, as well as more dangerous bacteria such as Salmonella and Hepatitus A being exposed to low levels of antibiotics released into the environment, and developing resistance.

In their paper (Environment Around False Bay, Cape Town, South Africa: Occurrence and Risk-Assessment Study – published in Environmental Toxicology and Chemistry in March this year) Petrik and Ojemaye note that Sulfamethoxazole accumulates in edible seaweeds. This meant “this compound could result in the development of antibiotic resistance by humans and other marine organisms that consume this seaweed and many others”.

Senior Lecturer Emeritus in the Division of Community Health at Stellenbosch University, Dr Jo Barnes, has been involved in overseeing students testing antibiotic resistance in bacteria such as e.coli for almost a decade.

Barnes said continual exposure to low levels of antibiotics, such as would be found in the sewage spills into Cape Town’s vleis and estuaries, would result in bacteria developing resistance.

She said antibiotic resistance, which led to the development of antibiotic resistant superbugs is a global concern, and research has found antibiotic resistant bacteria in the environment is linked to human waste water contamination.

Barnes said for decades, the medical fraternity was blamed for prescribing antibiotics when they were not needed, and people not disposing their antibiotic medication once they felt better rather than continuing the entire course. This meant bacteria that had not been killed were the stronger organisms, and developed a resistance to the medication.

She said normally there’d be a progressive resistance, with bacteria developing a resistance to weaker antibiotics and resistance gradually increasing as stronger antibiotics were introduced.

However, with the “massive pollution” ranging from waste water treatment plants being poorly managed, to industrial chemicals discharged into the waste water stream and sometimes directly into water bodies via storm water systems, bacteria have “jumped” the antibiotic levels.

“They (bacteria) are so strong that when they meet an antibiotic they just smile and go to tea,” said Barnes.

She said she oversaw research by students sampling the Plankenbrug River flowing past Kayamandi in Stellenbosch in 2001/2002. The tests showed a 60% resistance to antibiotics by e.coli in the samples. Kayamandi is only serviced by a clinic that dispenses first order, or low-level antibiotics, she said. When the same tests were conducted by visiting American students she was overseeing in 2019, the antibiotic resistance was 100%. This meant the same antibiotics being dispensed at the Kayamandi clinic would now have no effect on the bacteria causing the same illnesses.

“We are running out of drugs” to treat infections, said Barnes, and because human waste contained antibiotic compounds, ongoing sewage pollution in the environment was accelerating this problem.

Causes of pollution

City mayco member for water and waste, Xanthea Limberg says the majority of sewage overflows causing the pollution of rivers, vleis, and estuaries, are linked to people dumping solid objects in the sewers, illegally disposing of hazardous chemicals, as well as sewer pumps failing or being damaged due to theft or illegal dumping into the sewer system.

However, Marx believes in the case of Milnerton Lagoon, the main polluter is the City itself, as the City’s Potsdam Waste Water Treatment Works fails to treat waste water to minimum standard before releasing it into the Diep River. Marx said water quality tests below the treatment works’ outlet revealed far higher levels of e.coli than tests taken upstream of the outlet.

The national Department of Water and Sanitation dashboard publishing the results of monthly effluent quality tests of waste water treatment works show a number of the City’s treatment works are failing to meet the minimum guidelines. The Athlone WWTW, for example, achieved only 7.1% compliance for microbiological compliance over the last three months. This means high levels of e.coli and other bacteria from human waste has been flowing into the Black River, into which the Athlone plant discharges treated effluent at a rate of 105 million litres per day.

The Mitchell’s Plain, Cape Flats, Potsdam, Parow, Macassar, and Potsdam waste water treatment works are all indicated as failing.

Limberg said the City was inspecting the various catchments for factors that can be contributing to continued pollution levels so that these can be addressed.

“Work is under way to address infrastructural challenges as best as possible, and education and awareness programmes, such as the ‘Bin It, Don’t Block It’ campaign, are being undertaken around how to avoid sewer blockages,” she stated.

Limberg said Cape Town has experienced “unprecedented levels of new human settlements being established”. This created challenges such as obstruction of access to infrastructure for maintenance work, “and constraints to the provision of basic services.”