Millions of people depend on the Vaal River for their water but sadly it is heavily polluted by industry, sewage and agriculture. Some of this pollution you can see and smell, but most is hidden, including some highly toxic chemicals, such as mercury and DDT.
Mercury is considered one of top ten contaminants of major public concern and is listed as a priority substance in the field of water policy within the European Union. The toxic effects of mercury include damage to the brain, kidneys and lungs.
DDT is a notorious insecticide and endocrine disruptor. It can cause birth abnormalities and birth defects. It was banned in most countries after it was listed in the ‘dirty dozen’ deadly chemicals list at The Stockholm Convention in 2001. However, in South Africa, due to its ability to counter malaria, DDT is still routinely used.
South Africa is in fact one of the top four pesticide importers in Africa. This has led to heavy use of ‘Persistent organic pollutants’ (POPS) like DDT and they do not readily break down in the environment (they accumulate).
In a 2014 study in and around Johannesburg, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) such as DDT were detected in all the selected water bodies that were sampled… the same water used to feed mains supplies.
And it is not only mercury and DDT that are entering our water supplies. Other metals have been detected in the Vaal River such as silver, cadmium, lead and zinc. And none of these trace metals are removed by standard treatment processes.
Other ‘Persistent organic pollutants’ (POPs) include PCBs (polychlorinated biphenyls) which were also on the Stockholm list of banned chemicals. Alongside ‘alkylphenol ethoxylates’ (APEs) and other ‘brominated flame retardants’, these chemicals are bio-accumulative endocrine disruptors and highly toxic.
In a study carried out along the Vaal River (published in 2015), no less than seven APEs, six PBDEs (Polybrominated diphenyl ethers) congeners and two other flame retardants (PBB101 & HBCD) were detected in water samples.
‘Perfluorinated compounds’ (PFASs) are another class of highly persistent chemicals. They are widely used in industry (e.g. in the production of Teflon) and have also been found all along the Vaal River, creating problems for both the intake of drinking water and the consumption of fish (the two main exposure pathways in humans).
The sorry state of the Vaal River has led to widespread condemnation in the Gauteng province and residents have long urged the government to act.
It is not just chemicals causing problems either: raw sewage or the washing of corpses at mortuaries releases deadly pathogens. ‘Save the Vaal Environment’ (an NGO campaign group for the Vaal River) say much of the pollution stems from industrial waste and poor infrastructure which for them is not only deteriorating, but “possibly life threatening”.
In their words, “The Vaal River has become a dumping ground for toxic effluent from industry, mining and municipal waste water works”. Sadly, it is a river that millions depend on for potable water, but it is one of the most contaminated with chemicals, heavy metals and faecal matter in the whole of Africa, and there are no signs of an immediate solution or likely improvement.
 European UnionDecision no 2455/2001/EC of the European Parliament and of the Council of 20 November 2001 Establishing the List of Priority Substances in the Field of Water Policy and Amending Directive 2000/60/EC (2001)
 Gerber, Smit, Van Vuren, Nakayama, Yohannes, Ikenaka, . . . Wepener. (2016). Bioaccumulation and human health risk assessment of DDT and other organochlorine pesticides in an apex aquatic predator from a premier conservation area. Science of the Total Environment, 550, 522-533.
 Amdany, R., Chimuka, L., Cukrowska, E., Kukučka, P., Kohoutek, J., Tölgyessy, P., & Vrana, B. (2014). Assessment of bioavailable fraction of POPS in surface water bodies in Johannesburg City, South Africa, using passive samplers: An initial assessment. Environmental Monitoring and Assessment, 186(9), 5639-5653.
 Plessl, Gilbert, Sigmund, Theiner, Avenant-Oldewage, Keppler, & Jirsa. (2019). Mercury, silver, selenium and other trace elements in three cyprinid fish species from the Vaal Dam, South Africa, including implications for fish consumers. Science of the Total Environment, 659, 1158-1167
 Chokwe, T., Okonkwo, B., Sibali, J., & Ncube, O. (2015). Alkylphenol ethoxylates and brominated flame retardants in water, fish (carp) and sediment samples from the Vaal River, South Africa. Environmental Science and Pollution Research, 22(15), 11922-11929.
 Groffen, Wepener, Malherbe, & Bervoets. (2018). Distribution of perfluorinated compounds (PFASs) in the aquatic environment of the industrially polluted Vaal River, South Africa. Science of the Total Environment, 627, 1334-1344.
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