DDT the cause of intersex babies in Limpopo province in South Africa

In last night's episode of Carte blanche, the M-net current affairs programme revealed shocking findings linking the pesticide DDT to intersex births.

Date:

25 October 2009 07:00

Producer:

Joy Summers

Presenter:

Bongani Bingwa

Genre:

Medical and Health

There are few South Africans that by now aren't familiar with the story of Caster Semenya.
Her life and her biology have been splashed across every local newspaper. Suddenly the words 'intersex' and 'hermaphrodite' became headlines as a young athlete's life crumbled around her. If ever there was an athletic circus this was it!

Bongani Bingwa (Carte Blanche presenter): 'Against this background comes a new scientific study released this week that is shocking to say the least. It suggests that the spraying of DDT in Limpopo Province is having a definite impact on the number of cases of children born with urogenital birth defects. This may mean that incidents of intersex babies is on the increase and it's no accident of nature.'

Leading the study is Dr Riana Bornman, head of andrology at the University of Pretoria's Steve Biko Academic Hospital.

Dr Riana Bornman Bornman (Head of Andrology: Steve Biko Academic Hospital): 'There is an African proverb that says that he who asks questions cannot avoid the answers and I firmly believe that that is where we are at this moment.'

The questions for Dr Bornman arose in Thoyando, Limpopo Province. Here malaria often takes the lives of young children and their parents. The only pesticide that seems to control the problem is DDT. In 1996 South Africa scaled down its use but cases shot up from 11 000 to 62 000 in four years. On the edge of an epidemic, health authorities went back to DDT.

Dr Bornman: 'There has been a high suspicion that DDT might be causing those defects for a long time as an endocrine disrupting chemical, but this is the first proof that DDT might be playing a role.'

Although it is banned in most countries, South Africa and several others have special exemption from the Stockholm Convention to spray DDT on the inside and outside of rural village homes in high risk malaria areas twice a year.

Dr Bornman: 'DDT was introduced as a chemical in 1945. Since 1966 it has been sprayed annually in that area. So we have generations now been exposed to about 60 years of continuing DDT exposure.'

For the last six years Riana and her colleagues have travelled far north to the Tshilidzini Hospital in Limpopo. Here they examined 7000 newborn boys and girls to test Dr Bornman's theory.

Dr Bornman: 'There is a high prevalence of undescended testes, of hypospadia, also the combinations of these, also micro-penis.'

Riana concentrated the study on boys from the area as they are more vulnerable to birth defects. In the end 3310 newborn boys were examined and of those 357 or 11% had urogenital birth defects.

Bongani: 'Now of the sample you used, 11% of the participants presented with urongenical birth defects?'

Dr Bornman: 'That's right.'

Bongani: 'That seems high?'

Dr Bornman: 'It is high.'

The study shows that mothers who lived in villages that were sprayed had a 33% greater chance of having a child with a defect than mothers whose homes were not sprayed. And if that mother was a homemaker instead of being employed, she had a 41% greater chance of having a baby with a urogenital defect.

Bongani: 'Were you surprised at how high it was?'

Dr Bornman: 'I was surprised, but more shocked that surprised because I saw what the implications was and on many occasions when I examined the child I realised that for this child and this mother it was actually just the beginning of a very long and painful road.'

We could see what she meant. The pictures from Riana's study are shocking and so we have replaced the photos with graphics.

Dr Bornman: 'This is an example of a child with hypospadia where you can see that the opening is not at the tip of the penis but along the shaft of the penis. This is an example of a severe hypospadia - you can see the short penis and it is bent towards us, which will make passing water very difficult. This is one of the extreme cases of ambiguous genitalia. And in this case one can actually see the scrotal folds, which makes this - it is supposed to be a girl...'

Bongani: 'Shoo! these are hard to see.'

Dr Bornman: 'Yes, it is because what do you do? What do you say to the parents? [It is] impossible to tell whether the child is a boy or a girl.'

Bongani: 'Prof Bornman's study is not the only one to raise the alarm - there have been several released recently and they all point to the fact that while DDT seems to be the best available option to combat malaria, it is having a devastating effect on the endocrine system.'

Professor Tiaan de Jager completed a post doctoral study in Canada, where he documented the effects of DDT on rural men in a malaria area in Mexico. On his return, his team did a similar study on the fertility of 311 young healthy males living in a sprayed area in Limpopo. Measuring their blood for traces of DDT and then looking at the health of their semen.

Prof Tiaan de Jager (Head of Environ & Occupational Health: University of Pretoria, S.H.S.P.H): 'We found extremely high exposure levels in this population - about five times higher than what was found in Mexico where they phased out DDT in 2000 and about 50 times higher than found in the Canadian population.'

One of the worst features of DDT is that it travels. It has been found as far out as the Antarctic. Its effects on fertility were first discovered almost by accident by zoologists, when they noticed birds eggs were thinning, alligators in Florida weren't breeding, high numbers of fish and frogs were intersex. DDT, they observed, was disrupting the animals' endocrine systems.

Bongani: 'Tiaan, what is an endocrine disruptor?'

Prof De Jager: 'Endocrine disruptors are chemicals produced by various industries and the problem is that the body recognises it as if it is the female hormone oestrogen or they might even block testosterone receptors and scramble the hormone system.'

Simply put a race is on inside the body as the real hormones are blocked. The imposter jams the system and in a developing foetus chaos ensues.

Dr Bornman: 'And one can just imagine during this period of foetal development of the external gonads if one has a combination of a female-like hormone and you cancel out the male testosterone produced by the developing testis that one will have external genital defects.'

Tiaan's study on the effects of DDT on sperm is also groundbreaking. Never before has sperm quality been measured in healthy males where spraying is still taking place. The participants had bad sperm count, bad motility and bad appearance and his team's most recent paper shows DDT damages the sperm's DNA too.

Bongani: 'So what are the differences in these sperm?'

Prof De Jager: 'A normal sperm would take one second to cross the grid.'

Bongani: 'So we are looking for a Hussein Bolt there?'

These are good sperm and there are a lot of them. They easily pass the test of moving across a square on the grid within a second. But take a look at the sperm in which high levels of DDT are found in the participant's blood - sperm like this one seem to jog on the spot.

Bongani: 'This room epitomises the curious habits of scientists. Here at the North-West University snails are dissected till nothing is left of them but their penises and then they measure them. Now you may ask what possible use is that to the world?'

Prof Henk Bouwman (Professor of Zoology, North-West University): 'These are indicators that there are problems.'

Prof Henk Bouwman at North-West University has access to a snail collection going back to the1950s. Data from this has provided an invaluable comparison to current snail populations exposed to endocrine disruptors at the Rietvlei Dam. The best way to see what is happening to the environment it seems is to compare penises. And today's snails have been found wanting.

Bongani: 'So the snails are having shorter penises?'

Prof Bouwman: 'Yes, in Rietvlei Dam for instance near Pretoria we found that the penises of those snails there are shorter than the snails in Potchefstroom.'

For scientists like Henk a picture is emerging across the country of the effects of DDT.
At the Vaal River bird egg samples are thinner an effect of DDT. In Rietvlei Reserve outside Pretoria, eland had calcified testicles and in the Levuvhu River 60% of the fish are intersex. So when the story of Caster Semenya erupted Henk was concerned.

Prof Bouwman: 'When the story broke and I heard she was from Limpopo, the link was there and it is possible because she is from an area where fish are affected, snails are affected, birds might be affected - we're still looking at that, so it was no surprise. But it was shocking still.'

Henk has also conducted research into the presence of DDT in breast milk in women in Limpopo and KwaZulu-Natal.

Prof Bouwman: 'We have just received the results from a recent study we did on breast milk in both areas [using the] same techniques. Both have high levels.'

But it wasn't just DDT, they found pyrethroids too. These pesticides used against malaria are more neurotoxic than DDT.

Prof Bouwman: 'We have analysed and found the highest levels of pyrethroids in breast milk than anywhere else in the world, because nobody has anticipated that pyrethroids would accumulate in breast milk, but we found that.'

So potentially the child may have double exposure - first as the foetus, then later as a baby and research has shown that DDT in breast milk may affect a child's neurodevelopment.

Bongani: 'What will the consequence be of ignoring your study?'

Dr Bornman: 'If you had the opportunity to see one of those children with defects and you have seen the parents you will not be able to ignore what the findings of the study was.'

The scientists say that there is already enough evidence already from all the studies to start acting, but as realists they are deeply aware that people will die if DDT spraying stops. It's a catch-22 no one is happy with.