The release is part of a 9-week project in the region to reduce the mosca-da-bicheira or human botfly population, a large ugly green fly with a nasty bite. The botfly has caused substantial losses to the region's important livestock industry. Botfly larvae often thrive in the wounds of cattle and can even cause death to the animal.
According to the study, the nuclear-sterilized flies crossbreed with the native population, which then produce unfertile eggs, eliminating many if not all of the regional fly population.
Halfway through the project, it appears to be working. Nearly one third of the botfly eggs found recently in the region were infertile. That number is only expected to increase over the coming weeks.
"Everything is going as expected, and in fact we have been a little pleasantly surprised because in the other countries where this technique was used, they didn't have such immediate results," said Brazilian Coordinator Joal Pontes, Regional Supervisor of the Department of Animal Production of Brazil's Secretary of Agriculture in Alegrete, Rio Grande do Sul.
But if this seems like a peculiar way to control pesky insect populations, think again.
Although many may have never heard of Sterile Insect Technique (SIT), it was pioneered in the United States in the 1920s using X-rays to sterilize the insect larvae. Since the 1950s, when radioactive isotopes replaced X-rays, the technique has been used across the planet- primarily in the United States, Mexico and Central America.
According to the UN Food and Agriculture Organization (FAO), in the United States, this method has been used to eradicate or control the Mediterranean Fruit fly in Hawaii and California, the Caribbean fruit fly in Florida, the Mexican Fruit fly, Pink bollworm, the Codling moth, the Gypsy moth, Boll weevil, Stable fly, Tobacco hornworm, and the Cattle fevertick. As of the early 1990s, it was still being used in the United States to control the Caribbean fruit fly, the Mexican fruit fly, the Pink bollworm, the Gypsy moth, the Cattle fevertick and the Tobacco Budworm.
In his book, Nuclear Energy, nuclear engineering professor Raymond L. Murray, explains the "classic case" of SIT, which was used against the parasitic screwworm fly in Curaçao, Puerto Rico and the Southwestern United States. "After the numbers were reduced in the early 1960s, flies came up from Mexico, requiring a repeat operation. As many as 350 million sterile flies were released each week, bringing the infestations from 100,000 to 0. The annual savings to the livestock industry was approximately $100 million." Like the Botfly, the screwworm fly would lay its eggs in the wounds of animals, feeding on their flesh.
The process has also been used against mosquitoes in both the United States and India, the screwworm in Libya, and the sleeping sickness carrying-Tsetse fly in Zanzibar and in some parts of Africa.
As Pontes said early this week, "The technique is more than proven."
But is it safe?
A cursory Internet search reveals hundreds of documents and related pages on SIT and its successful application across the planet. Many lead with the words, "environmentally-friendly." None attempt to discuss the possible adverse health risks of releasing billions of radioactive bugs into the environment.
Pontes laughs at the idea. "It doesn't have any health risks for humans or the environment. If you had to measure the radiation, a banana has a lot more radiation than all of our boxes of flies," he says.
"It's not good science to compare 100 rads of background radiation with 100 rads of Ceasium-137 because they do different things to the body," says Joseph Mangano, executive director of the New Jersey-based Radiation and Public Health Project. "To say that it is not as dangerous because it's a lower dose, is really like comparing apples and oranges."
Mangano explains that there are different types of radiation. Background radiation found in rocks, soil and cosmic rays; X-rays, developed in the 1890s; and radiation from atomic bombs and nuclear reactors developed in the 1940s.
"There are some similarities, but there are plenty of differences. When we are talking about Ceasium-137, you don't find that in background radiation, you don't find that in X-rays. It's only found when you take a Uranium-235 atom and you split it," says Mangano.
The flies in the Brazilian experiment were sterilized in a facility in Chiapas, Mexico with Ceasium-137, but Cobalt-60 is also used in SIT technology to sterilize the pests.
Both are only created through nuclear fission, which occurs either when you explode an atomic bomb or when you operate a nuclear reactor.
Ceasium-137 has a radioactive half-life of 30.2 years, and if exposed to the human body in high enough dosages it can lead to mutation, cancer or birth defects, and can also be passed along through the reproductive process. Cobalt-60 has a half-life of 5.2 years and if exposed to the human body can also cause cancer. Cobalt-60 is often used in medicine for radiotherapy or radiography, and both isotopes have been used in food irradiation.
The million-dollar project along the Brazilian-Uruguayan boarder was financed by the Inter-American Development Bank (IDB). SIT has been promoted by the FAO, the International Fund for Agricultural Development (IFAD), the United Nations Development Programme (UNDP) and the International Atomic Energy Agency (IAEA).
"This has been highly investigated. It's a very safe technique," said Pontes. Nevertheless, cancer rates are rising across the planet. According to the California Cancer Registry, the incidence of invasive cancer in the Golden State grew by nearly 20% over the last three decades.
"I don't know a lot about screwworms and fruit flies", says Mangano. "But, I do know this. There is no radiation dose that's not totally free of harm. We know that It's not to say that these are terrible things. They do have a purpose, but you just have to understand the risk. Of course, it's not that easy in real life."
Michael Fox is a South America-based freelance journalist, radio reporter and documentary filmmaker. He is Co-Director of the recently-released documentary, Beyond Elections: Redefining Democracy in the Americas. For more articles, reports or videos you can visit his blog, Blending the Lines.
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