Bacteria-riddled river water used to irrigate most fresh produce in South Africa poses an extreme health risk.
The river water contains levels of E.coli bacteria that are as much as 10 000 times more than allowed by the World Health Organisation and the Department of Water Affairs, according to a study report obtained by The Times.
Not only is this dangerous for people but it might have a highly damaging effect on this country's international trading status and cause a suspension of exports of fruit and vegetables, the report warns.
The extensive research project was launched in 2007 amid growing concern that South African river water used for irrigating crops no longer met export standards set by the EU for fresh produce, or international health standards.
Professor Trevor Britz, of the food sciences department at Stellenbosch University, who led the R5-million study commissioned by the National Water Research Commission, called the situation "dangerous".
"If you fall into that water, you will die," he said of some rivers.
Microbial samples were taken from rivers regularly used to irrigate agricultural produce, such as the Eerste, Plankenbrug, Mosselbank and Berg rivers in Western Cape, the Baynespruit River in KwaZulu-Natal, the Mutshedzi River in Limpopo, the irrigation canal from Loskop Dam, the Olifants and Wilge rivers in Mpumalanga, Skeerpoort in North West and Gauteng's Klip River.
The rivers tested run through major agricultural communities such as Mpumalanga's Groblersdal - where citrus, table grapes, maize, wheat, vegetables, sunflower seeds, peanuts, lucerne and peaches are grown - and Stellenbosch, where grapes, pears, citrus, lettuces, strawberries, peppers, herbs and green beans are at risk.
Farmers pump water direct from the rivers and, without treating it, irrigate crops.
Researchers found that:
Human excrement, in particular, is severely polluting rivers;
In the Plankenbrug and Mosselbank rivers, near Stellenbosch, high concentrations of faecal indicators were present in more than 70% of the samples, and to a lesser extent in the Eerste and Berg rivers;
Concentrations of more than 1million microbes per 100ml of water were often measured. This compares with WHO and Department of Water Affairs guidelines, which state that levels of E.coli in irrigation water should not exceed 1000 per 100ml;
More than 30 types of bacteria and 180 phenotypic variations of E.coli were found; and
Other potential pathogens, such as staphylococci (responsible for food poisoning), Klebsiella (respiratory infections), Listeria (listeria infections) and salmonella (food poisoning, diarrhoea and kidney failure) were also found.
E.coli infections can lead to diarrhoea, dehydration and, in extreme cases, kidney failure and death.
Britz advised consumers to wash fruit and vegetables in sterilising fluid before eating them.
He said the risk of an infection from contaminated fresh produce could be illustrated by the 2011 E.coli outbreak in Europe, which resulted in at least 50 deaths and more than 4000 people becoming seriously ill.
In that instance, Germany had imported bean sprouts irrigated with contaminated water in Spain.
Many of the rivers tested in the South African survey are used daily by thousands of people for water sports and fishing. Some communities use the water for bathing and drinking.
Britz said "the whole" of Stellenbosch, and especially communties downstream from the town - including wine farms - were exposed to contaminated water from the Plankenbrug River.
In Mpumalanga, Groblersdal is fed by water from the Loskop Dam and vast crops of vegetables are irrigated with polluted water.
In a separate study of the Vaal River, high levels of E.coli were found in the dry months, but the bacteria were washed away during the rainy seasons, Britz said.
The pollution was caused by the poor management of sewage-treatment facilities, which leaked raw sewage into the rivers, as well as by the lack of ablution facilities in informal settlements, he said.
Popo Maja, spokesman for the Department of Health, said it had not examined the study results.
Sputnik Ratau, spokesman for the Department of Water Affairs, said that his department would respond after studying the report. "We shall interrogate the contents, also considering our normal inspections of river health and work of the Blue Scorpions."
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