Scientists have flagged the possibility of drug-resistant bacteria and contaminated foods resulting from commonly used medications and pesticides being absorbed by Cape Town’s coastal waters,
Emeritus Professor Leslie Petrik of the Department of Chemistry at the University of the Western Cape said chemicals flowed from source to sea and then back to our food in a circular loop because of their overuse, abuse, or simply their high stability.
Among the chemicals found in seawater and sediment samples were anti-inflammatory medication, caffeine, painkillers, antibiotics and antifungals, seizure medication, and antivirals. Herbicides and pesticides were also detected, reports News24.
Petrik said population growth had not been matched by increased sanitation infrastructure, resulting in sewage spills and contamination of rivers and coastline with bacteria and toxic chemicals. “Our coastline, from Green Point all around the Peninsula, is contaminated by chemicals from inadequately treated sewage.”
Additionally, the continual discharging of untreated sewage through the three marine outfalls at Green Point, Camps Bay and Hout Bay has added to the extensive chemical pollution of seawater, sediment and marine biota that Petrik’s team’s studies have detected.
UWC’s Dr Cecilia Ojemaye said that chemicals from pharmaceuticals, personal care products and pesticides were recorded in several areas of the coastline, including Camps Bay and Green Point.
There are marine outfalls in both areas.
But even areas without marine outfalls had traces of chemicals in them, Ojemaye said, based on samples drawn from False Bay.
“This shows that the same problems we face with marine outfalls happen with wastewater treatment plants. We need to build better (treatment systems),” she said. In her studies, she found that many sea creatures in False Bay and its surrounds also had traces of chemical contamination.
Petrik added that research had shown traces of nitrogen and phosphorus in South African waters, which could affect natural phenomena such as algae blooms, and expressed concerns around Cape Town's three marine outfalls, saying that while large waste items might be filtered out in the wastewater being released into the sea, chemicals could easily pass through the 3mm sieves used as filters.
'Not having a major ecological impact'
In addition, none of the wastewater treatment plants was equipped to degrade these compounds, the scientists said.
Marine outfalls have been a contentious issue in Cape Town for several years. In the most recent uproar, ActionSA threatened legal action to challenge the permit allowing the city to pump wastewater into the ocean.
The permit allows the release of screened sewage into the ocean at Green Point, Hout Bay and Camps Bay via pipes about 1.7km, 1.2km and 1km out to sea and about 32m, 35m and 28m deep, respectively.
The city’s acting Mayco member for water and sanitation, Siseko Mbandezi, said wastewater treatment plants and marine outfalls were not designed to remove contaminants like chemicals or pharmaceuticals.
“The preliminary treatment includes the removal of wastewater constituents like rags, sticks, floatables, grit and grease that may cause maintenance or operational problems with the treatment operations, processes and ancillary systems,” he said.
He added that the city was investing in multibillion-rand upgrades to wastewater treatment works so as to improve the quality of treated effluent leaving the plants, as well as the sewer network, which together, will have a far greater positive impact on inland and coastal water quality.
Mayco member for spatial planning and environment Eddie Andrews said the city had commissioned seven specialist studies over the past six years, as well as an environmental summary reeport prepared by an expert panel, on the marine outfalls.
He added that data collected from multiple studies indicated that the “effluent discharged through the Green Point, Camps Bay and Hout Bay outfalls is not having a major, deleterious ecological impact in the Cape Town outfalls study area”.
Bacteria resistant to antibiotics
Of 196 marine toxicity tests, “all were found to be non-toxic to marine biota”.
Dr Jo Barnes, senior lecturer emeritus at Stellenbosch University’s Faculty of Medicine and Health Sciences, said she found very high counts of bacteria along the beaches, rivers and stormwater drains.
Many samples collected at Fish Hoek and Hout Bay were full of bacteria that were resistant to many of the usual antibiotics used to prevent infections. In some samples, as much as 97% of the bacteria were resistant to one antibiotic commonly used to treat infections.
“Antibiotic resistance was believed to be driven by overuse of medication,” said Barnes.
“But there is growing evidence that environmental factors might be equal in the spread of antibiotic resistance.”
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