Gene-Silencing Pesticides: Risks and Concerns

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Frequently Asked Questions:

Why is this report urgent?

The report summarizes the latest science on the health, socioeconomic and environmental risks — and the many unknowns — surrounding experimental gene-silencing RNAi pesticide sprays that biotechnology and agrichemical corporations are seeking to patent and bring to market. The first such pesticide is likely to be submitted to the EPA for registration by GreenLight Biosciences by the end of 2020.

What are gene-silencing RNAi pesticides?

Agrichemical corporations such as Bayer, BASF, and Syngenta are using genetic modification techniques to develop pesticides that exploit a cellular process called RNA interference (RNAi), in order to switch off or “silence” genes that are essential for the survival of insects – thus killing them.

For example, RNAi could be applied as a foliar spray on leaves. After the pest eats the leaves, interfering RNA enters the insect’s stomach and silences a gene that is essential for cell division, following which, the pest cannot make functioning new cells and dies.

What is RNA interference?

RNA interference (RNAi) is a naturally occurring cellular process in plants, fungi, and animals, including insects. The RNAi pathway functions to control whether a gene is turned off or not. Genetic engineers are now able to make synthetic interfering RNA molecules in laboratory settings. The resulting RNAi pesticides can kill a pest by triggering a process in the organism that “silences” genes that are essential for survival.

What are potential environmental impacts of RNAi pesticides?

The technology is imprecise. Gene-silencing can occur both in the genome of the target organism as well as in non-target species. Some of these unintended genetic modifications could be inherited and persist in the environment for generations.

Environmental concerns include:

• Open-air experimentation: Entire agroecosystems could be affected. Genetically modifying organisms in the open environment makes controlling exposure difficult or impossible.
• Unintended silencing of genes: RNAi technologies are widely associated with off-target activity –the silencing of genes that weren’t intended to be silenced, both within the genome of target organisms as well as in related non-target species.
• Effects on non-target organisms: RNAi targeting a specific pest’s genes may bind to and shut down genes in other organisms as well. This off-target effect may extend beyond closely related species to potentially thousands of different species. A 2017 meta-analysis indicated that existing interfering RNAs developed for other target species could also directly impact gene activity in honeybees, and a 2019 study showed the uptake and exchange of interfering RNAs within bee colonies across generations. 
• Entrenching the pesticide treadmill: There is evidence suggesting that, as with other pesticides, targeted pests will rapidly develop resistance to RNAi pesticides.

What are potential health impacts of RNAi pesticides?

Key questions around human health impacts remain completely unstudied and must be fully investigated.

Public health concerns include:

• Inhalation of synthetic RNAi: Farmers, farmworkers, production workers and rural communities may be exposed to synthetic interfering RNAs via the potential spray drift. The risks pertaining to inhalation exposure are completely unknown.
• Altering crops’ genetic composition: Unwanted gene silencing could alter crops’ genetic composition in a way that raises safety concerns, such as altering levels of toxins or allergens.
• Dietary consumption of synthetic RNAi: Preliminary research suggests that naturally occurring interfering RNAs in our diet play a role in regulating physiological or pathological conditions in our bodies. This suggests that synthetic RNAi products may also interfere with human gene regulation, with unforeseen health implications. Further investigation is needed to fully understand the safety implications of consuming synthetic interfering RNAs.

Who owns the crops or insects that are modified by RNAi spray?

Gene-silencing pesticide sprays raise many questions and concerns about patenting and ownership issues.

Corporations developing RNAi pesticides are applying for patents that would give them ownership of exposed organisms and even their offspring, regardless of whether the exposure was intentional. This would result in a massive expansion of property rights over nature, ever more deeply entrenching the power of biotech companies over the food system in ways that would threaten farmers’ rights.

Are government regulations sufficient to ensure health and safety in relation to the environment and people?

RNAi pesticides currently fall outside of existing domestic and international regulatory structures and therefore have yet to be regulated in most parts of the world. Oversight and regulations for interfering RNA applications should include independent, transparent health and environmental assessment, including  examination of potential long-term impacts, before being allowed to enter the market or environment, and products of all genetic modification should be traceable, and labeled as GMOs.

Are gene-silencing pesticides safe for eaters?

RNAi pesticides are being described by developers as “eco-friendly” and “natural” because the active ingredient, the interfering RNA, is a form of genetic material that exists in all organisms. However, equating the safety of naturally occurring interfering RNAs with novel synthetically produced interfering RNAs lacks scientific grounding.

Synthetic interfering RNAs are being developed as insecticides, and it depends on the individual interfering RNAs, and the modified organism, as to whether they are safe for consumption. Further, developers may alter their chemical structure, or add nanoparticles and other synthetic materials to RNAi products to enhance their function — for example, to make them more resistant to degradation. They should thus be judged on a case-by-case basis and not merely assumed to be equivalent to their natural counterparts.

Also, as stated above, preliminary research suggests that naturally occurring interfering RNAs in our diet play a role in regulating physiological or pathological conditions in our bodies. This suggests that synthetic RNAi products may also interfere with human gene regulation, with unforeseen health implications. Further investigation is needed to fully understand the safety implications of consuming synthetic interfering RNAs.

What are sustainable and healthy alternatives?

Based on evidence from scientific assessments available, it is not possible to assure the safe use of RNAi products, designed to induce genetic modifications in organisms in the open environment.

Rather than perpetuating the pesticide treadmill, ecological farming methods that underpin organic and other forms of ecological agriculture, offer a true solution. A growing body of science shows that farmers who rely on ecological methods for pest management instead of pesticides can meet or outperform their conventional counterparts in terms of yield and profits. Ecological farming techniques build healthy soils that confer greater pest immunity to plants and increase biodiversity in farming systems to disrupt the growth of pests and to foster natural predators. This includes crop rotations, cover cropping, composting, reducing tillage, and planting habitat for beneficial insects.