Over the past 12 months in Paraguay, the area planted with soy has grown to a record 2.6 million hectares, and most of it is GM. The World Land Trust estimates that more than 90 per cent of the Atlantic Rainforest in the south has been lost to make way for crops, taking with it thousands of unique bird and plant species and endangered animals, such as the jaguar.
Now agri-businesses and large-scale farmers are targeting the Gran Chaco, an area of dry forest that is just as important to wildlife. In a short flight over the vast area, there was clear evidence of deforestation, in the long lines of trees felled for burning.
The impact on communities is also cause for concern, according to FoE. Thousands of people claim to have been driven off the land that has sustained them for centuries. In the main square in the capital Asuncion, indigenous people have set up camp, and tarpaulin shacks by the sides of the road are a common sight now. FoE estimates that 100,000 people have been driven into the urban slums because of the expansion of soy production in Paraguay.
In Itakyru, in the east of the country, a forest community claims that poisons "rained from the sky", resulting in women and children being taken to hospital.
Amnesty International has confirmed that a number of communities have complained that aerial spraying is being used to force people to leave their homes so that the land can be reclaimed for soy production. This has resulted in civil disturbance, with armed men brought in to guard crops.
Dr Miguel Lovera, head of Paraguay's environment agency, Senave, says aerial spraying should not have been carried out in areas where indigenous people were living. He also agrees Silvino was certainly killed by ''acute intoxication with pesticides".
A small Paraguayan 2006 study reported in the Journal of the American Academy of Pediatrics found women living within 1km of sprayed fields were twice as likely to give birth to a child with deformities.
Dr Lovera's greatest concern about the GM soy boom his country is enjoying is the irresponsible use of chemicals used to protect the GM crops from weeds and infestation.
Most of the GM soy planted in Paraguay is a variant known as RoundUp Ready Resistant, which is resistant to a common weed killer, glyphosate. Farmers can use it without harming the crop, and biotech companies claim they use less because only weeds are targeted.
Dr Lovera says the amount of pesticide used in Paraguay has grown tenfold over the past 10 years to 200 million tons in 2006. This is not a problem in itself as glyphosate, if used as directed, is safe, according to manufacturers. But Dr Lovera says that the huge profits to be made from growing GM soy, local corruption and a lack of regulation is driving many farmers to buy cheaper brands, mixing chemicals with no idea of the consequences, and spraying near people's homes.
He is leading the Paraguayan Government's efforts to stop farmers spraying within fifty metres of people's homes, in a strong wind or in high temperatures.
"The picnic is over," he says. "Farmers should start being serious and professional, and comply with the law."
British consumers have a role to play, too, according to Oskar Rivas, the Environment Minister in Paraguay's new socialist government. GM soy might not be grown in the UK but it is part of our daily diet. A recent investigation by The Daily Telegraph found that every supermarket in Britain stocks meat and dairy from animals that could have been fed GM soy, as well as possibly being used in brands including Cadbury and Unilever.
"You have the right to demand cheap milk and meat but you also have the right to demand milk and meat from environmentally sound sources," says Señor Rivas.
While Sr Rivas accepts it is too late to stop GM being grown in Paraguay, he insists that more non-GM could also be grown. He points to the lead taken by Paraná state in Brazil, where the local government is promoting non-GM soy as a premium crop.
New initiatives, such as the Round Table on Responsible Soy, backed by the World Wildlife Fund, will encourage this sort of production by issuing a new label for soy – including GM – in a sustainable way. Some British supermarkets are already signing up. In addition, Friends of the Earth International is working with a local charity, Sobrevivência, to teach communities environmental law and organic farming techniques.
"At the moment we are all losing out," says Paraguayan Sr Rivas. "With a different structural process we could all win."