Horizontal gene transfer is
uncontrollable. Unlike chemical pollutants which break down and become
diluted out, nucleic acids are infectious, they can invade cells and
genomes, to multiply, mutate and recombine indefinitely.
Horizontal gene transfer is by no
means unknown to our Governments. Among the scientific advice given by the
UK Ministry of Agriculture, Fisheries and Food (MAFF) to the US Food and
Drug Administration (FDA) at the end of 1998  are the following
- Transgenic DNA can spread to
farm workers and food processors via dust and pollen.
- Antibiotic resistance marker
genes may spread to bacteria in the mouth, as the mouth contains
bacteria that readily take up and incorporate foreign DNA (see above).
Similar transformable bacteria are present in the respiratory tracts.
- Antibiotic resistance marker
genes may spread to bacteria in the environment, which then serves as a
reservoir for antibiotic resistance genes.
- DNA is not readily degraded
during food processing nor in the silage, hence transgenic DNA can
spread to animals in animal feed.
- Foreign DNA can be delivered
into mammalian cells by bacteria that can enter into the cells.
- The ampicillin resistance gene
in the transgenic maize undergoing ‘farm-scale’ field-trials
in the UK and elsewhere is very mutable, and may compromise treatment
for meningitis and other bacterial infections, should the gene be
transferred horizontally to the bacteria. The potential hazards of
horizontal gene transfer are unlike those we have ever experienced (see
The dangers of generating new
viruses and bacteria that cause diseases, and spreading drug and
antibiotic resistance among the pathogens, were both foreseen by the
pioneers of genetic engineering. That was why they called for a moratorium
in the Asilomar Declaration of 1975. But commercial pressures cut the
moratorium short, and guidelines were set up based on assumptions, every
one of which has been invalidated by scientific findings since . Within
the past 20 years, drug and antibiotic resistant infectious diseases have
come back with a vengeance. Geneticists have confirmed that the
diseases are due to new viral and bacterial strains that have been created
by horizontal gene transfer and recombination. Horizontal gene
transfer is now recognized to be widespread, involving the entire
biosphere, with bacteria and viruses in all environments serving as
reservoir and highway for gene multiplication, gene swapping and
trafficking. Has genetic engineering contributed to creating the new
pathogens, and will it continue to do so through the unregulated release
of naked and free nucleic acids?  The possible links between genetic
engineering biotechnology and the recent resurgence of infectious diseases
are summarized in Box 6.
Dormant and relict viral
sequences have been discovered in the human and other animal genomes at
least 20 years ago . Viral sequences have also been discovered recently
in plant genomes . Viral transgenes are found to recombine with
defective viruses to generate infectious recombinants . Recombination
between exogenous and endogenous viral sequences are associated with
animal cancers . It is not inconceivable that the cauliflower mosaic
viral promoter, which is in practically all first generation of transgenic
plants, may recombine with dormant/relict viral sequences in the genome to
regenerate infectious viruses , in view of the fact that viral
promoters have modules in common. Recombination hotspots may be associated
with all transcriptional promoters , including those of animal viruses,
such as the SV40 and cytomegalovirus, used in animal and human genetic
engineering . This possibility should be addressed by empirical
investigations, particularly in view of the recent claim that a
significant part of the toxicity of certain transgenic potatoes fed to
young rats may be due to the transgenic construct or the transformation
process, or both .
In the light of the existing
evidence, the most dangerous naked/free DNA may be coming from the wastes
of contained users of GMOs which are discharged into our environment.
These include constructs containing cancer genes from laboratories in
research and development of cancer and cancer drugs, virulence genes from
bacteria and viruses in pathology labs and all kinds of other novel
constructs and gene combinations that did not previously exist in nature,
and may never have come into being but for genetic engineering.
Despite the growing body of
evidence of hazards from the innumerable exotic naked nucleic acids that
are created and released in increasing amounts into the environment from
the burgeoning biotech industry, there is no effective regulatory
oversight, nor is there any indication that our Government is prepared to
establish effective regulatory oversight (see Box 7).