It has taken nearly two months, but Food Standards Australia and New Zealand has finally responded to criticisms of its regulation of GM foods after it was accused of “systemic neglect” in its regulatory regime by Canterbury University’s Professor Jack Heinemann.
The response is well worth a read for Sciblogs regulars who have followed the debate Heinemann and colleagues have led of late about dsRNA and the potential of dsRNA molecules present in genetically modified food to interfere with the genes of humans who consume it.
Last year, Heinemann teamed up with Dr Judy Carman and the Australian anti-GM activist group Safe Food Foundation to release a paper suggesting that GM wheat being developed by the CSIRO could cause liver damage in humans or as the foundation alarmingly put it “devastating consequences causing serious illness or death”.
The paper was criticised by scientists as it had not been through peer review by a major journal. Robust debate ensued here on Sciblogs, with Prof Heinemann contributing this guest post. Sciblogger Prof Peter Dearden chipped in with some typically insightful analysis here.
In March, Prof Heinemann, Dr Carman and Sarah Agapito-Tenfen of the Federal University of Santa Catarina, Brazil, authored a paper that appeared in the journal Environment International and suggested regulators in Australia, New Zealand and Brazil were failing to properly test genetically modified food that could could pose a risk to humans. The Press newspaper carried the story on its front page and more scientific argument generated some heat, it not much light on the subject.
In that respect, the decision by the FSANZ to step back and let the dust settle was a wise one. It’s extensive report is well laid-out and gives a good overview on the state of the scientific literature concerning the dsRNA issues that these researchers have sought to highlight.
Overall FSANZ concludes: “The weight of scientific evidence published to date does not support the view that small dsRNAs in foods are likely to have adverse consequences for humans.”
– In formulating their hypothesis, the authors have not taken into account the fact that small dsRNAs are ubiquitous in the environment and in the diverse range of organisms we consume as food, including plants and animals. This establishes a long history of safe human consumption which pre-dates the use of such techniques in GM plants.
– The authors failed to adequately acknowledge that developing oral therapies based on small dsRNAs targeted against human viruses and other diseases such as cancer has so far been unsuccessful because of the barriers that exist to their uptake, distribution and targeting within the body.
– The authors have also underestimated the strengths of the GM food safety assessment to detect possible unintended effects, including those that could arise from the use of gene silencing.
– 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 address the safety of GM foods developed using gene silencing techniques. This approach enables additional studies to be requested should that be necessary to further inform the safety assessment of a particular GM food.
– FSANZ will continue to monitor the scientific literature for any new developments which may be relevant to GM food safety assessment.
It particular, FSANZ points out that the researchers have relied heavily on a single paper (Zhang et al.):
The core of the argument presented in the Heinemann et al. (2013) paper is based on the research findings published by L. Zhang and others (Zhang et al., 2012a) in which certain plant miRNAs derived from common food crops were reportedly found in the bloodstream of humans. Further, one miRNA, which is highly enriched in rice, was reported to inhibit the expression of a protein in human liver, leading the authors to suggest that miRNAs can influence gene expression across phylogenetic kingdoms. This paper lead to speculation (e.g. Jiang et al., 2012) that small duplex RNAs (eg siRNAs and miRNAs) present in foods could be taken up by epithelial cells lining the human gastrointestinal tract, be packaged into microvesicles, secreted into the bloodstream and subsequently make their way to target organs where they would enter cells and exert some effect on the expression of endogenous genes. No other evidence for this as a biological phenomenon in humans currently exists however.
While there have been several commentaries on the implications of these findings (Hirschi, 2012; Vaucheret and Chupeau, 2011; Zhang et al., 2012b), it is notable that there have been no other publications which corroborate the transmissibility of gene silencing effects from foods to humans.
Over at the Science Media Centre we will later today be posting reaction to the report from FSANZ – including hopefully from Prof. Heinemann, who today via The Press, expressed his disappointment on an initial look at the paper, that FSANZ had not supplied data on testing of dsRNA in GM foods.
The FSANZ response, arguably, is no surprise.But Prof Heinemann and colleagues, even their critics agree, have raised some issues worthy of discussion.
The view however, from the regulator responsible for assessing the safety of our food, genetically modified or not, suggests there is scant evidence to back up the bold claims that in effect suggested a public health disaster was waiting to happen.