Safety of New Pesticide Technology Is Under Review
Scientists have found a way to use a trick of nature to increase crop yields, combat hard-to-kill pests, grow coffee beans with no caffeine and even save the honeybee.
The technology also could help farmers sidestep some of the issues that have fueled opposition to the genetically engineered foods that are now on the market. Critics, however, fear that biotech giants such as Monsanto Co. are rushing the technology to market before some potential side effects are fully understood.
Federal regulators are now assessing the safety of one application of the technology. It would make way for a new generation of pesticides that could, for example, kill agricultural pests with supposed pinpoint accuracy, sparing harmless insects.
“It’s very exciting and offers potential in a lot of ways,” says Bryce Falk, a University of California-Davis scientist who is trying to use the technology to stop the spread of a disease that is devastating U.S. orange groves.
The new technology, called RNAi for short, allows scientists to switch off key genes in plant and animal cells in a way that nature already does. Human cells use RNA molecules, for example, to destroy viruses. The discovery of the process earned two American scientists the Nobel Prize in 2006.
The RNA molecules can be engineered into the plant or animal or applied from the outside via a spray, for example. RNA interference has already been used by plant scientists to tweak soybeans to produce more healthful oils and to engineer virus-resistant food crops. Other future applications include producing coffee beans that are naturally decaffeinated.
Biotech giant Monsanto is employing RNAi to develop new pesticides, including a treatment designed to reverse declines in honeybee populations by using RNAi to control a virus that mites carry into hives. Department of Agriculture scientists have been conducting similar research.
Bees are critical to pollinating a variety of crops, so success in combatting the virus could be a huge public relations coup for the biotech industry, which has struggled to convince critics of the public benefits of genetic engineering.
Monsanto also is using the RNA technology to develop virus-resistant vegetables and to address problems that have resulted from the widespread use of genetically engineered crops.
The molecules also are being engineered into corn to help combat the rootworm larvae, some of which have developed resistance to a toxin in genetically engineered corn varieties now available to farmers.
Knowing products like this could be headed to market, the Environmental Protection Agency has scheduled an Oct. 29 meeting of a scientific advisory panel to review the possible health and environmental risks that the agency should address when companies such as Monsanto apply for approval to commercialize the RNA products.
The agency said it “recognizes the need to better understand the scientific issues concerning the assessment of the risks to human health and the environment that RNAi technologies may pose before any regulatory decisions concerning these products can be made.”
In an email, the agency said it has already approved two such products, virus-resistant plums and potatoes.
Monsanto wants to add RNA molecules to its popular glyphosate herbicide to kill weeds that have become resistant to the chemical. Another product would help combat larvae that are resistant to a toxin in genetically engineered corn crops.
Two USDA scientists, including one who’s expected to be a member of the EPA panel, published a paper in the August issue of the journal BioScience outlining a number of potential hazards posed by RNA pesticides. More research is needed to find out how long the pesticidal molecules linger in the environment and to prove that lab testing can adequately predict what impact the pesticides will have in the field, the scientists said.
Robert T. Fraley, Monsanto’s chief scientist, calls the technology “cool new stuff” and said his company welcomes the way the EPA is approaching the issue.
“I’m really appreciative that they’re setting the framework,” he said. “We’ve had a lot of discussions with the regulatory agencies around the framework over RNAi technology.”
The meeting will be held one day before the EPA convenes a scientific advisory panel to review the problems with rootworm resistance. A bacterium gene that was engineered into the corn plants renders them poisonous to the larvae, but some of the insects have developed resistance to the toxin, known as Bt.
Unlike the Bt toxin, RNAi theoretically wouldn’t hurt harmless insects. RNAi also could be used to kill pests such as aphids that Bt toxins can’t be used against, Falk said.
The technology also could help crop developers avoid concerns that new genetically engineered products could induce allergic reactions. That’s a problem for scientists because inserting a new gene in a plant or animal produces new proteins. Companies such as Monsanto are required to prove to federal regulators that any new proteins they create would pose no threat to consumers. RNA, on the other hand, has generally been considered safe to eat.
But Bill Freese, senior policy analyst for the advocacy group Center for Food Safety, worries that companies such as Monsanto are rushing the technology to market without knowing the consequences. The micro RNA that companies want to put into pesticides may be more precise than the Bt toxin but it may not be precise enough to avoid harming other insects, Freese said.
There could be human health concerns, too, Freese said, pointing to a Chinese study that suggested that RNA molecules found in rice can affect the way the body controls cholesterol levels.
“It’s a familiar situation where we have cutting-edge science … and immediately we want to start applying this before we know all the ins and outs. That’s pretty concerning,” said Freese, whose organization has battled Monsanto in court over genetically engineered crops.
He said the new products amount to “techno-fixes” that are aimed at correcting problems, such as the weed and insect resistance, that were caused by the overuse of the gene-altered crops.