NATIONAL NEWS - A new study has established that sharptooth catfish found in the Klip River, which feeds into the Vaal River, South Africa’s second-largest river, contains banned pesticides that can cause cancer when consumed by humans.
The river runs through high-density residential areas, including Soweto, Lenasia and Fleurhof in the south of Johannesburg. Some residents supplement their diet by fishing the popular catfish in the rivers as well as dams fed by them. The Conversation Africa’s Nontobeko Mtshali asked Rialet Pieters to explain the implications of these findings.
What are these banned pesticides?
The pesticides we looked at are collectively known as organochlorine pesticides. They are used in agriculture to control insects that eat crops.
We did a human health risk assessment on the sharptooth catfish found in Orlando Dam and the Fleurhof and Lenasia areas in the south of Johannesburg. We chose this fish because it’s popular and widely consumed. The pesticides we targeted in the sharptooth catfish were lindane, heptachlor, aldrin, dieldrin, endrin and dichloro-diphenyl-trichloro-ethane (DDT). We found levels of heptachlor, DDT, and lindane in the fish.
All of the pesticides except for one, DDT, which is used against malaria-carrying mosquitoes, are banned in South Africa. So they should not be in the river. It’s not clear how they ended up in the Soweto, Fleurhof and Lenasia areas, though they could have made their way down the river from malaria-prone rural areas of the country.
The pesticides, with the exception of DDT, were banned by the international community under the Stockholm Convention on Persistent Organic Pollutants because of their harmful effects on the health of humans and wildlife. South Africa is a signatory to the convention and is obliged to reduce and eliminate the use of all the compounds listed in the convention.
