All the myths and assumptions of a "vanishingly small" risk of horizontal gene transfer from GM food into humans have now been blown apart.
In the prevailing culture of denial, regulators and industry have peddled a science-free rationale on how impossible any harm from horizontal gene transfer is.
But now we know:
- DNA in food is not digested down to an amorphous mix of its nucleic-acid subunits in the gut: it can survive in strands (up to and including as big as genes) which can, and do, pass into the body
- Dietary DNA can circulate to all tissues, where it can be incorporated into the genome if it has even a short sequence similar to the genome of the consuming organism
- Most DNA isn't a gene which codes for protein but is regulatory in nature and highly active in altering gene function; unlike genes, such DNA can consist of very short sequences.
- Some DNA is naturally prone to mutation and change
- Some DNA is mobile and can jump from one location in the genome to another, or into another genome
The pseudo-science which claims that the DNA carefully crafted by human hand to work in soya or maize couldn't possibly affect human consumers is definitely wrong in the case of 80% of currently commercialised GM crops. And possibly in all of them.
The problem is that those carefully constructed genes won't work unless they have a carefully constructed promoter to switch them on. So far, the most powerful promoter identified and routinely used is DNA copied from the 'Cauliflower Mosaic Virus' (CaMV), a pathogenic plant virus.
Take another look at all the things "we know" about DNA listed above. All of these can be said of the CaMV promoter. However, the real nightmare is that this plant viral DNA, when isolated from the virus particle, can alter the expression of genes in just about any organism. That includes our food animals, pathogenic microbes, and us.
A study published in late 2014 found DNA from the CaMV promoter incorporated into the genome of rats fed chow containing GM soya, GM maize or both. The rat tissues which were analysed and found to be genetically transformed were the blood (which can carry the CaMV DNA to any part of the body), the liver (which is the main organ of detoxification), and the brain (which would be expected to be protected from large, invasive molecules in the blood).
All three tissues demonstrated the same rate of CaMV DNA uptake.
Although the rats were fed the GM chow for only a maximum 90 days, a clear cumulative pattern of CaMV DNA insertion emerged.
In some cases, evidence suggested that the whole (and obviously active) promoter DNA sequence had inserted into a tissue. However, truncated DNA sequences from this promoter are also known to be active.
The Institute of Science in Society has been warning about the danger of putting artificial CaMV promoters into our food since 1999. Salient hazards include the activation of dormant viruses in the genome, the creation of novel viruses by recombination, and the triggering of gene-function disturbances which lead to cancer. It points out that other similar aggressive promoters designed to make genes express out of context are in use in GM food crops. The Institute ends:
"companies and regulators should face prosecution for causing damage to health and criminal negligence".
Scary indeed. The study suggests people whose staple diet is GM maize or GM soya are steadily accumulating bits of CaMV promoter DNA throughout their bodies.
A standard 90-day rat feeding study may well pick up the first signs of metabolic disturbances caused by the viral DNA, but they will be highly variable. The current fashion in data interpretation seems to allow these to be dismissed as not biologically important. The big issues like cancer or viral emergence will take much longer than 90 days to become inescapably obvious.
Livestock don't live long enough to be hit by the major health problems arising from the CaMV promoter: but humans do.
The current 90-day feeding trial protocols were devised for testing toxins and are routinely used to test artificial gene products. They are clearly wholly inappropriate for safety-testing of food containing mobile, globally active DNA arising as a by-product of the artificial gene construct.
Is anyone checking vulnerable populations for the presence of CaMV DNA in their genome?
- Hanaa A. S. Oraby, et al., 2014, Addressing the issue of horizontal gene transfer from a diet containing genetically modified components into rat tissues, African Journal of Biotechnology 13:48
- CaMV 35S Promoter in GM Feed that Sickened Rats Transferred into Rat Blood, Liver and Brain Cells, Institute of Science in Society Report 7.01.15
CC Photo credit: Nathan Nelson on Flickr