Rats fed genetically modified crops suffered more premature deaths, tumours, kidney and liver problems, a worrying new study has found.
The research suggests rats fed GM maize, grown with or without herbicide “Roundup”, or those given doses of the herbicide in water suffered more health problems than those on a standard diet.
But UK experts criticised the study, published online in the journal Food and Chemical Toxicology, for using a small sample of a type of rat susceptible to tumours and providing limited data on their research.
The study, led by French scientists from Caen University and backed by research organisation CRIIGEN, looked at maize that is genetically altered so that it is not affected by the herbicide, which is used to tackle weeds in the crop.
Dr Michael Antoniou, molecular biologist at King’s College, London, and a member of the CRIIGEN scientific council, said the study showed an “extraordinary number of tumours developing earlier and more aggressively – particularly in female animals”.
“I am shocked by the extreme negative health impacts,” he said.
He said rats had long been used to test products to see how they might affect humans.
“This is as good an indicator as we can expect that the consumption of GM maize and the herbicide Roundup impacts seriously on human health.”
The findings have led to a concerned reaction on Twitter from scientists and health campaigners, debating over whether the results were reliable.
In Britain GM maize is not grown and cannot be eaten directly by consumers, but hundreds of thousands of tons are imported each year for use in animal feed, and meat from animals fed on GM maize is sold in British supermarkets.
The study found up to 50% of males and 70% of females died prematurely, compared to only 30% and 20% in the control groups, and developed two to three times more large tumours.
The researchers said the GM maize and the herbicide both caused similar damage to the rat’s health when consumed together or on their own, even at lower doses.
Females developed fatal tumours and pituitary disorders, while males developed more liver and kidney problems than the control group.
The researchers said previous studies feeding rats GM feed and pesticides had only been undertaken for 90 days, but the first detectable large tumours had emerged after this time, raising questions over the regulatory process for the products.
Patrick Holden, founder and director of the Sustainable Food Trust called for all foods containing imported GM maize to be clearly labelled.