THIRD WORLD NETWORK BIOSAFETY INFORMATION SERVICE
Dear friends and colleagues,
Re: RNAi–based pesticides and GM crops will need special safety testing
A peer-reviewed paper in the journal Bioscience draws attention to potential hazards on nontarget species of pesticides and GMOs made with RNA-interference (RNAi) gene-silencing techniques. The hazards include off-target gene silencing, silencing the target gene in unintended organisms, immune stimulation, and saturation of the RNAi machinery.
The paper, authored by two employees of the US Department of Agriculture Agricultural Research Service, notes that the nature of these new pesticides and GMOs makes the prediction of toxic effects challenging. In addition, the rapid development of RNAi applications has challenged scientists to identify and fill key knowledge gaps that underlie the environmental implications of large-scale, pesticidal RNAi-based crops.
The authors raise the concern that current toxicity testing is inadequate to assess the safety of these new technologies. They therefore suggest the development of a special testing and regulatory framework to assess the safety of such RNAi-based pesticides and GM crops. Other scientists have previously highlighted how regulators have not assessed the safety of these RNAi-based pesticides and GM plants, and have developed and provided a safety testing procedure for such crops and products (See BIS, 25 March 2013: New kinds of GM plants and pesticides not being assessed for safety).
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Item 1
RNA-interference pesticides will need special safety testing
A new technology for creating pesticides and pest-resistant crops could have effects on beneficial species that current toxicity testing will miss
Press release, American Institute of Biological Sciences, 16 Jul 2013
Standard toxicity testing is inadequate to assess the safety of a new technology with potential for creating pesticides and genetically modifying crops, according to a Forum article published in the August issue of BioScience. The authors of the article, Jonathan G. Lundgren and Jian J. Duan of the USDA Agricultural Research Service, argue that pesticides and insect-resistant crops based on RNA interference, now in exploratory development, may have to be tested under elaborate procedures that assess effects on animals’ whole life cycles, rather than by methods that look for short-term toxicity.
RNA interference is a natural process that affects the level of activity of genes in animals and plants. Agricultural scientists have, however, successfully devised artificial "interfering RNAs" that target genes in insect pests, slowing their growth or killing them. The hope is that interfering RNAs might be applied to crops, or that crops might be genetically engineered to make interfering RNAs harmful to their pests, thus increasing crop yields.
The safety concern, as with other types of genetic modification and with pesticides generally, is that the artificial interfering RNAs will also harm desirable insects or other animals. And the way interfering RNA works means that simply testing for lethality might not detect important damaging effects. For example, an interfering RNA might have the unintended effect of suppressing the action of a gene needed for reproduction in a beneficial species. Standard laboratory testing would detect no harm, but there could be ecological disruption in fields because of the effects on reproduction.
Lundgren and Duan suggest that researchers investigating the potential of interference RNA pesticides create types that are designed to be unlikely to affect non-target species. They also suggest a research program to evaluate how the chemicals move in real-life situations. If such steps are taken, Lundgren and Duan are optimistic that the "flexibility, adaptability, and demonstrated effectiveness" of RNA interference technology mean it will have "an important place in the future of pest management."
The article by Lundgren and Duan can be accessed ahead of print as an uncorrected proof at http://www.aibs.org/bioscience-press-releases/resources/Lundgren.pdf
Contact: Tim Beardsley
703-674-2500 x326
American Institute of Biological Sciences
Item 2
RNAi-based insecticidal crops: Potential effects on nontarget species
Jonathan G. Lundgren and Jian J. Duan
Bioscience 63, Aug 2013: 657-665
http://www.aibs.org/bioscience-press-releases/resources/Lundgren.pdf
The potential hazards posed by RNA interference (RNAi)–based pesticides and genetically modified crops to nontarget organisms include off-target gene silencing, silencing the target gene in unintended organisms, immune stimulation, and saturation of the RNAi machinery. Non-target organisms will vary in their exposure to small RNAs produced by genetically modified crops at a previously unrealized scale. Areas that warrant future work include the persistence of insecticidal small RNAs in the environment, describing crop-based food webs to understand those species that are most exposed, sequencing genomes for species to proactively understand those that may be affected by RNAi, and substantiating that laboratory toxicity testing can accurately predict the field-level effects of this technology. The costs and benefits of pesticidal RNA must be considered relative to current pest management options as pesticidal RNAs move from a theoretical approach to being used as a practical tool.