Within the wide scope of work that Umvoto undertakes, water quality monitoring and contamination assessments are a key part of water resource development and management. Over the last two years, Umvoto has undertaken sampling for contaminants of emerging concern (CECs) in the Cape Flats and Atlantis Aquifers in the Western Cape, with the aim of investigating the potential occurrence, sources, fate, and impacts of CECs in these vital aquifers.
What are CECs?
CECs are classes of natural and synthetic chemicals that were previously not analysed for or detected in the environment and occur at very low concentrations. These chemicals include pharmaceuticals, pesticides, personal care products, disinfection by-products, and industrial chemicals; the persistence and toxicity of which continue to be investigated by scientists.
The presence of disease-causing chemicals and pathogens has been well studied for many decades, such as the diarrhea causing E. coli and chronic poisoning from arsenic-contaminated water, among others. However, in the 1990s, studies in the United States and other Western nations began investigating the occurrence and fate of these previously undetected chemicals, called CECs. Given that thousands of these chemicals are manufactured, utilised, and disposed of daily, the potential human health and environmental risks remain unknown and thus their use and disposal continue to be unregulated; particularly in South Africa and the wider African continent where research on CECs lags behind the global North.
What are the sources of CECs?
Although some CECs come from natural sources (e.g., caffeine and salicylic acid), the majority of CECs are the result of various anthropological activities and are most prevalent in urban environments. Many scientific and technological advances aim to improve human lives, livelihoods, and lifestyles with a plethora of synthetic chemicals produced in industry present in everyday products and inadvertently contaminating water resources. For example, eutrophication is a familiar phenomenon, where surface water bodies become over-enriched in nutrients that enter the environment due to extensive use of fertilizers (nitrogen, phosphorus, and potassium) in agriculture. Similarly, the use of synthetic pesticides and herbicides in agriculture means more crops are produced, but the pesticides and herbicides also end up in the water.
How do CECs enter water resources?
One of the ways in which CECs enter the environment is through industrial and domestic wastewater, for example, via the manufacture of pharmaceuticals by industry; the flushing of old and unused medications down the toilet or sink; or from metabolism and excretion of medications. These wastewaters are reticulated to local wastewater treatment works and, after treatment, the effluent is disposed into rivers and oceans or used to recharge aquifers. A key problem is that many CECs are recalcitrant, and traditional wastewater treatment methods tend to be inefficient at eliminating CECs or reducing their concentrations. One example of these persistent contaminants is a class of industrial chemicals called PFAS (per- and poly-fluoroalkyl substances) and dubbed ‘forever chemicals’ because they barely degrade in the environment. PFAS are used in a wide range of consumer and industrial products, such as fire-fighting foams, fast-food packaging, paints, and non-stick cookware.
Another examples stems from chlorination, which is extensively used for the disinfection of potable water. When combined with specific organic compounds, this may cause a class of CECs known as disinfection by-products (DBPs), which are recognised carcinogens. So, although disease causing pathogens are eliminated by chlorination, carcinogens may be produced in the process. Further examples include CECs that are airborne and settle on land surfaces, which are subsequently carried by surface runoff or infiltration to receiving water resources.
Why should we care about CECs?
Human health impacts of many CECs remain unknown and continue to be studied. However, some of the known health impacts include thyroid disease, reproductive effects, developmental effects in children, as well as cancer. Another key concern is the potential development of drug resistance due to sustained, low-level exposure to pharmaceutical drugs in drinking water, including ARVs, the use of which is ubiquitous in South Africa due to the ongoing HIV/AIDS epidemic in the country. It’s vital to know what’s in our water resources. This knowledge can guide the regulation of CECs including their use, disposal, and treatment.
What is Umvoto’s role?
Umvoto has wide-ranging experience in the development and management of groundwater, including desktop and field assessments to site high-yielding boreholes away from contaminated areas, sampling groundwater and surface water, and interpreting results to assess the natural chemistry and possible contamination, modelling contaminant transport and assessing groundwater vulnerability and developing protection zones, and where contamination is present, recommending the most viable treatment method(s) available.