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ISIS Report 22/02/12
Regulation of Transgenic Insects Highly Inadequate and Unsafe
USDA set a dangerous precedent for a permissive
regulatory regime over environmental releases of transgenic insects that is now
adopted across the world Dr. Mae-Wan
Ho
A fully
referenced version of this report is posted on ISIS members website
and is otherwise available for download here
Please circulate widely and repost, but you must give the URL of the original and preserve all the links back to articles on our website
USDA’s Environmental Impact Statement “scientifically
deficient”
Belatedly, the scientific community has woken up to the
parlous state of regulation over the environmental release of genetically
modified or transgenic insects. Scientists at the Max Planck Institute for
Evolutionary Biology in Plön, Germany assessed the regulatory process in detail
and find it distinctly unsatisfactory in a commentary published January 2012
[1]. It is more than ten years since ISIS objected to the environmental release
of transgenic pink bollworm moths ([2] Terminator insects give wings
to genome invaders, ISIS report) proposed by the US Department of
Agriculture (USDA).
Over the past 9 years, 14 US
government-funded field trials have taken place of the GM pink bollworm moth,
an agricultural pest of the cotton plant; but there has been no scientific
publication of experimental data in all that time, and in only two
instances have permit applications been published [1]. When the German
scientists requested information from the USDA on the unpublished applications,
they were refused; and had to submit a Freedom of Information Act request. Even
then, no experimental data were forthcoming, most likely because the data did
not exist; as an administrative procedure allows US regulators to rely on
earlier similar environmental assessments; and that procedure is applied all
too often.
Not surprisingly, the world’s
first environmental impact statement (EIS) on transgenic insects issued by US Department
of Agriculture in 2008,was judged [1] “scientifically deficient” in considering
environmental risks, relying largely on unpublished data and basing endorsement
for releases on just two laboratory studies on the Mediterranean fruit fly Ceratits
capitata, which is just one of the four species covered by the document. The
other species were the pink bollworm moth P. gossyfiella, the Mexican fruit
fly Anastrepha ludens, and the oriental fruit fly Badrocera dorsalis.
In fact, the same EIS also claimed “some applicability” for transgenic
mosquitoes Aedes or Anopheles.
The EIS made selective use of
unpublished or non-peer reviewed ‘evidence’ to support contentious conclusions,
a practice explicitly forbidden by US federal regulations in drafting EIS.
Another problem with the EIS is
that it dealt only with first generation transgenic insect technology that
involves either the expression of fluorescent markers for monitoring population
size, or the use of repressible dominant lethals (RDLs) to kill all offspring
of individuals released into the environment, or all the female insects in
release programmes requiring only male insects, with the intention to reduce wild
populations [3, 4] (Terminator
insects – a primer, Terminator
Insects – The Killing of Females, ISIS reports). Newer techniques for
replacing rather than reducing natural populations were not considered. Furthermore,
the document appears to treat all genetic modifications as equivalent, which is
definitely not the case, as some modifications are more effective, or less
risky than others.
Nevertheless, this highly inadequate EIS from
the USDA APHIS (Animal and Plant Health Inspection Service) set the tone for the
permissive regulation of transgenic insect releases all over the world.
Worldwide releases of transgenic insects follow USDA
model
Within the past several years, there have been several
environmental releases of transgenic insects that follow the USDA model.
Oxitec, a UK company based in
Oxford, is in the frontline of developing transgenic mosquitoes for controlling
infectious diseases such as dengue. Their intention to carry out an
international series of field releases of transgenic mosquitoes first came to
light in Malaysia in 2008 ([5] Terminator
Mosquitoes to Control Dengue? SiS 39). Although that particular
release was halted, the company has since resorted to illegal, secret field
releases across the world, aided and abetted by regulatory authorities.
According to
a briefing from Friends of the Earth in the United States [6], the first field
release of transgenic mosquitoes from Oxitec took place between 2009 and 2010
in the Cayman Islands, a British Overseas Territory, and consisted of 3 million
mosquitoes. Malaysia was the second to host Oxitec’s experiments at the end of
2010 with 6 000 more transgenic mosquitoes released. Then, between February and
June 2011, more than 33 000 were released in Brazil. The
first releases on Cayman Islands took place in secret with no public consultation,
and no informed consent. There are no biosafety laws on Cayman Islands, despite
the fact that the UK is a Party to the Cartagena Protocol on Biosafety.
Similarly, the release in Malaysia in 2010 was only made public in a press
release dated 25 January 2011, more than a month after the trial began on 21
December 2010.
While the Cayman Islands regulatory authorities failed to
publish any regulatory documents prior to the release of transgenic mosquitoes,
the Malaysian regulatory authorities failed to cite published experiments in
their regulatory documents [1].
A document [7] entitled: “Risk Analysis – OX513A Aedes
aegypti Mosquito for Potential Release on the Cayman Islands (Grand
Cayman)” was uploaded to the UK parliament website on 13 January 2011, more
than a year after the release commenced, and only as the result of questions
asked at the House of Lords. It made reference to unpublished reports and other
dubious sources to support key assertions [1], such as “The characteristics of
the OX413A Aedes aegypti have been thoroughly evaluated by several
institutions worldwide, e.g. in France, Malaysia..and Thailand.”, and “OX513A
uses genetic methods instead of radiation to achieve sterility, therefore the
genetically sterile insects have been reported to be fitter and competitive…”
Oxitec has planned to release more transgenic mosquitoes
in the Florida Keys early in 2012, though this has been delayed [6], perhaps
partly as the result of public outcry.
Other countries reported to be
evaluating the release of transgenic insects include France, Guatemala, India,
Mexico, Panama, Philippines, Singapore, Thailand, and Vietnam [1].
Hazards for health and environment ignored
The most troubling aspect of
Oxitec’s document, according to the German scientists, is [1] “the absence of
any discussion of potential environmental or health hazards that are specific
to the released OX513A stock.”
The particular RDL construct in OX513A
is engineered to express the synthetic protein tTA at very high levels, and
female mosquitoes biting humans could inject it into their bloodstream with
potential harmful consequences. Females expressing high levels of tTA can arise
if a resistance to the RDL construct evolves in the wild, or if female
transgenic mosquitoes were not completely excluded by the sorting mechanism.
More significantly, OX513A males are known to be only partially sterile, and
when they mate with wild females, they will produce 2.8 to 4.2 % the normal
number of eggs, half of which will be biting daughters.
Another major hazard is the
potential for horizontal gene transfer through the remobilization of the
transposon-derived vectors used in creating the first generation transgenic
insects, which we have highlighted in ISIS’ original submission to the USDA [2],
and reiterated several times since, most recently in [8] Can GM
Mosquitoes Eradicate Dengue Fever (SiS 50). We
provided evidence that the disabled piggyBac vector carrying the
transgene, even when stripped down to the bare minimum of the border repeats,
was nevertheless able to replicate and spread, because the transposase enzyme
enabling the piggyBac inserts
to move can be provided by transposons present in all genomes, including that of the
mosquito. The main reason initially for using transposons as vectors in insect
control was precisely because they can spread the transgenes rapidly by
‘non-Mendelian' mean within a population, i.e., by replicating copies and
jumping into genomes, thereby ‘driving’ the trait through the insect
population. However, the scientist neglected the fact that the transposons
could also jump into the genomes of the mammalian hosts including human beings.
Although each transposon has its own specific transposase enzyme that
recognizes its terminal repeats, the same enzyme can also interact with the
terminal repeats of other transposons, and evidence suggests extensive
cross-talk among related but distinct transposon families within a single
eukaryotic genome.
The use of the piggyBac transposon has been plagued by problems of instability in
transformed Aedes aegypti [9]; and large unstable tandem inserts of the piggyBac
transposon were prevalent [ 10]. In spite of instability and resulting
genotoxicity, the piggyBac transposon has been used extensively also in
human gene therapy [11]. A number of human cell lines have been transformed,
even primary human T cells, using piggyBac [12]. These findings leave us
in no doubt that the transposon-borne transgenes in the transgenic mosquito can
transfer horizontally to human cells. The piggyBac transposon was found
to induce genome wide insertion mutations disrupting gene functions.
Female A. aegypti mosquitoes mate as a rule before taking a first blood
meal [13]. Thus living human blood will be exposed to the piggyBac
carried by the mated female. What would it take to activate the mosquito-borne
transposon to infect human blood? Joe Cummins pointed out [8]: “No more than an
encounter with Baculovirus [acting as a stimulus] that could enter
through open cuts or sores, or with inhaled dust. The piggyBac
transposon GM construct could wreak havoc in the human genome, causing numerous
insertion mutations and other untold, unpredictable damage.”
There are yet other reasons why transgenic
mosquitoes are not a solution to controlling disease vectors (see [14] Transgenic
Mosquitoes Not a Solution, SiS 54).
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