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New Long-term Study: Higher death, tumour rates in rats fed GM RR maize

Immediate release (19 Sep 2012)

Calls to: Pete Riley, GM Freeze 07903 341 065

A new independent lifetime study has found that a diet of Monsanto’s Roundup Ready maize increases the rates of death and tumours in laboratory rats. [1]

The CRIIGEN research team [2] used Monsanto’s NK603 Roundup tolerant maize to feed rats over their whole lifetime. Feeding trials used to assess the safety of GM crops and herbicides, such as Roundup, do not normally last longer than 90 days.

In this two-year study rats were fed a diet of GM maize, GM treated with Roundup and the parental variety of non-GM maize with and without access to Roundup treated water supply. The research found:

  • Death rates in rats fed GM maize was 70% in females and 50% in males compared to the 20% and 30% in control animals.
  • Female death rates were 2-3 times higher the controls.
  • Mammary tumours were the most common cause of death in females.
  • Treated male rats showed increased liver and kidney problems.

The researchers suggest the observed effects are due to the hormone-disrupting effects of Roundup and the impacts on metabolism of the GM trait that makes the maize tolerant to Roundup.

Monsanto’s GM Roundup Ready maize currently mainly enters the UK as animal feed from North and South America. Meat, milk and dairy products from GM-fed animals are not labelled to show where GM feed is used.

Commenting Pete Riley of GM Freeze said:

These results raise major doubts about the overall safety of GM crops and the herbicide Roundup.

The length of the feeding study goes well beyond that required in official risk assessments and is more like the exposure levels of animals and people consuming such crops.

We need urgently to find out if Roundup residues are coming through into the human diet as a result of GM Roundup Ready maize being fed to livestock, poultry and farmed fish.

Regulators across the world should suspend approvals for GM crops sprayed with Roundup. When this weedkiller is applied directly to the growing crop, food and feed are far more likely to have higher residues present.

Monsanto should do the ethical thing and withdraw such GM crops from the market until they are proven to be safe. Mosanto should also be held fully liable for the health impacts of their products.



[1] Séralini G-E, Clair E, Mesnage R, Gress S, Defarge N, Malatesta M, Hennequin D, Spiroux de Vendômois J, 2012. “Long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize”. Food and
Chemical Toxicology, available online from 19 September 2012 (copy available on request)

[2] See CRIIGEN (Committee for Research & Independent Information on Genetic Engineering)