Scientific American on the Pusztai GE Food Safety Controversy


The furor in Britain raises health safety concerns about genetically
modified foods

British scientist Arpad Pusztai, who was fired last year from the Rowett
Research Institute in Aberdeen, Scotland, and banned from speaking to the
press for a while, told a parliamentary select committee on March 8 in
London he had no regrets about his comments that led to his dismissal.
Humans, he had said, were being used as guinea pigs in a vast experiment
with genetically modified (GM) foods.

Pusztai's testimony to the committee followed headlines in British
newspapers screaming that a scientist had been gagged and his findings
suppressed to keep secret that genetically modified foods threaten health.
Conspiracy theories abounded--namely, that President Bill Clinton had
personally pressured Prime Minister Tony Blair to give biotechnology
companies, including Monsanto, a freer rein in planting GM crops. An
admission on March 1 from John Prescott, secretary of state for
Environment, Transport and the Regions--that the British government has
indeed received representations from its U.S. counterpart about GM
crops--did not help.

The furor started last August, when Pusztai released to the media results
that he said indicated that rats fed potatoes genetically engineered to
contain a lectin from the snowdrop plant--a naturally occurring
insecticide--had suffered damaged immune systems and stunted growth of
vital organs. The results stood in stark contrast to safety claims made by
biotech companies and to the received wisdom of the harmlessness of
transgenic crops.

Four days after his announcement Pusztai, a renowned scientist who
pioneered studies on the effects of lectin, was suspended. The Rowett
institute stated he had muddled his findings. Quietly, over the ensuing
months, Rowett invited a group of independent scientists to audit Pusztai's
work--and the audit found that his conclusions were indeed erroneous,
although it absolved him of the more serious charge of scientific fraud.

Other scientists, though, came to Pusztai's defense. Two researchers
forwarded his data to 21 scientists, who later issued a memorandum in
February that said, "We are of the opinion ... that the consumption of the
GM potatoes by rats led to significant differences in organ weights and
depression of lymphocyte responsiveness compared to controls."

A study that criticized the Rowett audit and confirmed Pusztai's results
also got some backing. Done by pathologist Stanley Ewen of Aberdeen
University, a friend of Pusztai's, the work was examined by Thorkild
B¯g-Hansen, a lectin expert from the University of Copenhagen (and one of
the researchers who forwarded Pusztai's results to others). He concluded
that "Dr. Ewen's results clearly showed the errors in the audit report that
followed Dr. Pusztai's suspension from the Rowett Research Institute. The
experiments clearly showed that ... the GM potatoes caused a major
intraepithelial lymphocyte infiltration similar to inflammatory responses."

Vyvyan Howard, a toxicopathologist at the University of Liverpool and
Pusztai supporter, says that the results showed the main risk of GM food to
be "long-term, low-dose toxicity from subtle changes to the nature of the
food chain." He describes Pusztai's findings as unexpected and not totally
attributable to the lectin. In other words, the genetic modification
process itself was causing unpredictable outcomes. Speculations include
virus promoters (mechanisms used to switch on the inserted genes) and
possible unintended switching off of beneficial genes. "It is precisely
this type of finding which means that animal testing for developmental
toxicological effects is essential," says Howard, who also argues that the
"mixture problem" must be addressed as well. "None of us eat only a single
food. The effects of mixtures to my knowledge have not been addressed," he
notes, concluding that "human volunteer testing would probably be

Tom Sanders of King's College London, a nutrition expert and a member of
the government's Advisory Committee on Novel Foods and Processes, is not
convinced by Pusztai or his supporters. After reviewing Pusztai's
experiments, he maintains that all they definitively proved was that eating
raw potatoes, which are indigestible, is harmful to mammals-- "something
that has been known for many years," he asserts.

Sanders also says that carrying out full pharmaceutical-style testing on GM
foods would be impossible, because low-level poisons ostensibly from GM
products would not appear in ordinary toxicological testing. He also points
out that testing for human allergenicity with animals is not possible. He
suggests instead that known allergens be banned for use in GM food, along
with markers used to tell which foods have been modified.

Jim Dunwell of the plant sciences department at the University of Reading
has another point against Pusztai: all potatoes are not alike, and toxin
levels can vary widely between different tubers before any modification is
carried out. "Many assertions that are made against GM crops are not backed
up by sound science," he contends.

Both Sanders and Dunwell note the potential benefits from genetic
modification--food engineered to prevent tooth decay or to deliver
vaccines. Genetic engineering could cut the need for pesticides. But both
also admit its risks. Sanders says that "each crop needs examination on a
case-by-case basis. It is dangerous to extrapolate from one to another."
They also admit that genetic engineering could be a threat to the
environment, especially if tests are not conducted locally. "The English
countryside is not the American prairie," Sanders comments.

In the next few months, the Royal Society--an independent science academy
established in 1660--will complete its own review of Pusztai's findings and
of its own stance on the toxicity and allergenicity of GM foods. Only then
might residents of Britain--and the rest of the world--move a step closer
toward understanding the health threats, if any. But anyone after a
definitive answer will be disappointed--science doesn't deal in absolutes,
and the debate will surely rage on.

--Peta Firth