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Science Alert: Experts Respond

FSANZ defends stance on gene ‘silencing’ – experts respond

Posted in Science Alert: Experts Respond on May 22nd, 2013.

DNA strand with codeFood Standards Australia New Zealand (FSANZ) has responded to criticism alleging products relying on a new gene silencing technology are entering the food supply without adequate scrutiny.

Earlier this year, a scientific review raised concerns that double-stranded RNA molecules produced in new genetically modified crops could pose a risk to human health.

The paper’s authors, including Professor Jack Heinemann at University of Canterbury, called on regulators to require experimental evaluations — including bioinformatic sequencing, in vitro tests, animal feeding trials and potentially even clinical trials — before approving any genetically modified foods using the technology.

Further background and comments on the original paper are available here.

FSANZ has now released a report responding to the concerns raised, concluding:

  • The weight of scientific evidence published to date does not support the view that small double-stranded RNAs (dsRNAs) in foods are likely to have adverse consequences for humans.
  • There is no scientific basis for suggesting that small dsRNAs present in some GM foods have different properties or pose a greater risk than those already naturally abundant in conventional foods.
  • The current case-by-case approach to GM food safety assessment is sufficiently broad and flexible to addresses the safety of GM foods developed using gene silencing techniques.

Full conclusions and a copy of the FSANZ report can be found here.

The SMC contacted scientists for further comment on FSANZ response to the criticisms in Heinemannet al‘s article. Feel free to use these quotes in your reporting. If you would like help reaching these or other experts, please contact the SMC (04 499 5476; smc@sciencemediacentre.co.nz).

The SMC contacted scientists for further comment on the FSANZ response to the criticisms in Heinemann et al’s article. 

Dr Tony Conner, Science Group Leader, Agresearch. Dr Conner’s research career has focused on the applications of plant biotechnology and genomics to crop improvement and the integration of these emerging technologies into plant breeding programmes. He comments:

“The FSANZ response to Heinemann et al 2013 is well considered and very thorough. It demonstrates that the risk claims in the article are an overreaction based on dubious scientific evidence about the biosafety risks in plants genetically modified with gene silencing approaches.

“The public can take comfort from two key aspects:

1. Double-stranded RNAs do not present a new issue for food safety. They are very common in a wide range of organisms, including many fresh foods that have a long history of safe use in our diet.

2. The current approaches used by regulatory bodies, including FSANZ, are sufficiently robust to address food safety of GM products with dsRNAs.”

Assoc Prof Peter Dearden, Director, Genetics Otago, University of Otago:

“Food Standards Australia and New Zealand (FSANZ) have responded, remarkably promptly, to Prof Jack Heinemann’s review published in ‘Environment International’. Their response is comprehensive, well researched, and dismisses Prof Heinemann’s points entirely.

“Prof Heinemann’s paper suggested that double stranded RNAs produced in GM crops to change the way genes are regulated might pose a human health risk through that RNA passing into human cells and changing the way our genes are regulated. FSANZ dismiss this possibility stating that such RNA molecules are ubiquitous in nature, including in the food we eat, suggesting such molecules do not pose a health risk.  They review the evidence that shows that the development of RNA therapies targeting viruses and other diseases, designed to manipulate genes in just the way suggested by Prof Heinemann, have been unsuccessful, because humans do not easily take up such RNAs. FSANZ then suggest that Prof Heinemann has underestimated the ability of GM food safety testing to detect off-target and unintended effects.

“FSANZ’s report provides a sensible and well-argued counterpoint to Prof Heinemann’s claims, and I find their report very convincing. The difference of views expressed by FSANZ and Prof Heinemann spring, I think, from one controversial paper (Zhang et al, 2012, Exogenous plant MIR168a specifically targets mammalian LDLRAP1: evidence of cross kingdom regulation by microRNA. Cell Research 22(107):126). This paper is central to Prof Heinemann’s claims, as it shows that an RNA molecule made by rice can be detected in human serum, and that that RNA can regulate one of our genes. This paper is disputed, as some authors have criticized the techniques used, and other experiments have failed to find evidence of plant RNAs in animals (Zhang et al, 2012, Analysis of plant derived RNAs in animal small RNA datasets, BMC Genomics, 13:381). More pertinently, the paper does not show that the rice RNA, when eaten, regulates a human gene, just that the RNA can be detected, and in cell culture experiments adding a synthetic version of the RNA will change the expression of a human gene. We have no evidence that ingested RNAs from food affect human genes.

“My opinion is that FSANZ have got it right. Their assessment is that the risk to human health of double stranded RNA constructs used in GM plants is negligible, and I agree. I do, however, think that one of Prof Heinemann’s suggestions, that bioinformatic examination of potential human targets of the RNAs made in GM plants should be carried out to ensure that such RNAs cannot affect human genes, is worth doing. In my experience it is possible to design numerous double-stranded RNA molecules to affect the expression of a gene. I would like to think that when designing such RNAs it would be common practice to avoid regions with strong similarity to human genes, just to remove any possibility of an effect on humans. While I firmly believe that the risks of such RNA constructs are negligible, performing this analysis is trivially easy, and thus worth doing.

“The safety of our food is a key issue. I am pleased to see our regulatory agencies responding to scientific criticism and new scientific knowledge. Such criticism and response is vital to ensure we have effective, evidence based, regulation of food safety issues.”

Prof Jack Heinemann, School of Biological Sciences, University of Canterbury (co-author of the original paper), comments:

“Our food safety watchdog, FSANZ, is relying on assumptions instead of seeking evidence when confronted by a newly identified risk in GM foods.

“When FSANZ says it is not “likely” that small dsRNAs in foods will harm humans, it effectively acknowledges this is still possible, and so a risk. Yet it proposes not even testing for that risk until the “weight of evidence” suggests it is doing harm. We say consumer protection should be forward looking – do the tests now: don’t wait for harm to be proven.

“In responding to our peer-reviewed research, FSANZ does not deny that it uses assumptions, rather than scientific testing, to address the risks we identified.

“FSANZ is silent on what specific tests and techniques it uses to guard against unintended effects from the new dsRNA molecules that it is approving as safe for use in GM food crops. What we do know is that it does not require animal feeding studies of any kind. In the approvals that we reviewed, it had never even required tests for detecting dsRNA in the blood of animals, much less required tests that would reliably detect unintended harmful effects from dsRNA. FSANZ does not monitor for effects on people after approval or specify any particular monitoring be done by the developing companies. FSANZ needs to do more than just say its processes work; it needs to be forthcoming on what evidence it relies on to show that all these new dsRNA molecules are no threat to humans.

“To come to its position, FSANZ takes our statements out of context, deflects the issues, and makes misleading assertions.

“The “weight of evidence” it rests its opinion upon is either not appropriate for the testing of new dsRNAs in food, or invokes an absence of evidence when no evidence was ever sought. FSANZ should require this testing as it has the power to in its legislation, it has the option to under international food safety guidelines, and it has a responsibility to the people of Australia and New Zealand to do this.

“Contrary to what FSANZ asserts, there is scientific basis for suggesting that small dsRNAs present in some GM foods may pose a greater risk than those already naturally abundant in conventional foods. Some of these molecules are proven as pesticides. They can have potent effects on animals and should be tested before use on humans.

“RNA molecules are in the food we eat, but to extrapolate from the safe use of food with naturally occurring forms to those that are engineered and unique to new kinds of food is wrong. Proteins of all kinds are also in the food we eat but new proteins are evaluated for the potential to be toxic or allergenic in food. These dsRNA molecules can participate in fundamental biological reactions in human cells and so must be tested to be determined safe.

“Let’s use scientific evidence to see if the new dsRNAs in approved and future foods are safe. Science and public health will then be the winner, whatever the outcome.”

John Reeve, Principal Advisor (toxicology) Ministry of Primary industries, comments:

“The method of assessment of GE Foods conducted by Food Standards Australia and New Zealand (FSANZ) on behalf of Australia and New Zealand is exactly the same as internationally established as appropriate and used by all the major regulatory authorities in the world. The need for data has been carefully considered to ensure that any genetic modification getting into the human food chain does not pose any unacceptable risk.  The risk assessors involved in the FSANZ process are highly competent and very experienced both domestically and internationally.

“I note the suggestion that clinical testing be conducted on each new food, but this would seem to be quite impractical.  This sort of testing is not required for any current dietary risk assessments systems.  Any risk assessments carried out on foods are always based on the data available at the time, and are never set in stone.

“Thus, at any time, new information on a substance or food will always be considered carefully, and if necessary a risk assessment will be appropriately updated.  Revision of risk assessments is occurring around the world and within the WHO expert committees on a regular basis and the acceptability of foods are constantly being updated. This would apply in the case of any genetically modified food that has an approval.”

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