/ 17 May 2010

‘Toxic DDT a huge health risk’

In the same week that activist group Africa Fighting Malaria released a book on how the chemical DDT has been vilified, the Water Research Commission (WRC), a South African non-governmental organisation, warned that DDT poses a huge health risk to humans.

South Africa should start looking for other solutions to control malariacarrying mosquitoes besides the controversial pesticide DDT, the commission said.

According to the latest research released by the Council for Scientific and Industrial Research (CSIR) and the University of Pretoria, funded by the WRC, eating chicken, fish and vegetables produced in DDT-sprayed areas is putting people at risk of developing illnesses such as cancer.

The study followed a recommendation for further research made by a group of international researchers who had reviewed 494 studies investigating human health consequences of DDT use in 2008.

But Africa Fighting Malaria disputes the research, declaring that its ‘irresponsible declarations” are putting lives at risk.

DDT was the flavour of the month back in the 1960s before environmental activists took up the cause against the chemical and highlighted its hidden dangers.

Rachel Carson, viewed as the mother of the modern environmental movement, in her 1962 book Silent Spring started the backlash against the chemical. She called DDT the ‘elixir of death”.

Since then the harmful effects of the chemical have been debated and studies have linked it to cancer, diabetes, low birth weight, miscarriages, birth defects in boys and infertility.

But it remains one of the best ways, if not the most successful, to fight the tropical disease. Though locally and internationally banned as a pesticide since 2001, DDT’s effectiveness in fighting malaria resulted in a World Health Organisation exemption for its use in this regard — under strict controls.

It is widely used to combat malaria in South Africa and the South African government has no problem using it.

‘The department of health has been spraying DDT since the 1940s and has not experienced any harmful effects of DDT [on] human health,” said the department’s spokesperson, Fidel Radebe.

Richard Tren, director of Africa Fighting Malaria, believes that South Africa should continue spraying problem areas. He is a co-author of The Excellent Powder, a book about DDT’s political and scientific history, in which he argues that environmentalists had vilified the chemical unfairly.

The book disputes thousands of studies and says well-orchestrated and well-financed alarmist campaigns against DDT, without scientific justification, led to its pariah status. The book blames the environmental movement for costing poor countries struggling with malaria thousands of lives.

The book certainly takes a dig at Carson for starting the backlash against DDT. It cites scientists who believe that DDT is not as toxic as the studies have shown and argues that it is toxic, but not in the extreme.

Tren said the use of relatively small quantities of DDT in homes was safe and that DDT was only dangerous when used in large quantities, for example to spray crops.

The books points out that no human has ever died as a result of exposure. Spraying with DDT to control malaria has been an ongoing annual practice in Limpopo Province since 1996.

The WRC study was conducted in Vhembe District Municipality with sites at Lotanyanda, Hasana, Tshikonelo, Xikundu Weir and Mhinga in Limpopo. The villages make use of water from the tributaries of the Luvuvhu River system and the Albasini and Nandoni dams.

Tren is critical of the study done in Limpopo and claims it misrepresents DDT as the cause of the problem.

‘They have taken DDT and looked for a problem. They did not take the problems and look for other causes. That the problems do exist is not necessarily disputed. But that it might be caused by other factors should at least be considered. It requires further research.”

He said the research has already led to some Limpopo residents showing DDT sprayers the door.

In 1996 the government decided to stop using DDT because of environmental concerns. Until then the average annual number of malaria cases was fewer than 10 000 and deaths rarely exceeded 30 a year. But four years later the disease made a dramatic comeback.

In 2000 the number of malaria cases spiked to more than 65 000 and 458 people died. DDT was reintroduced after mosquitoes became resistant to pyrethroid, the ‘safer” pesticide for which the government had dropped DDT. The intervention immediately made an impact.

In 2001 malaria declined nationally to 26 506 cases and the number of deaths dropped to 119. Between 2000 and 2008 malaria cases were reduced by 88% to 7 796 cases, with 46 deaths recorded. But unlike Tren, there are many scientists who believe DDT is toxic and that it presents a danger to communities.

The WRC’s study will put more pressure on the South African government to look at the potential problems of DDT. ‘Ingestion of chicken or fish and vegetables grown in DDT-sprayed areas poses a high risk of cancer and toxic effects,” said Annatjie Moolman, WRC research manager responsible for the study.

‘Ingestion of water does not contribute largely to the calculated risk of developing cancer.” The study also highlights that DDT is an endocrine-disrupting chemical that adversely affects hormone production.

Exposure of male embryos to such chemicals during the early stages of foetal development has been linked by previous studies to increased incidences of male reproductive health disorders, including hypospadias, undescended testes, intersexuality, subfertility and testicular cancer.