Poisoned lab rats are normal

August 2015
Photo from Creative Commons
Concerns have been raised before that the outcome of routine experiments supposed to investigate effects of GM feed are unreliable. This is because, for example, too-low levels of GM in test feeds, or the use of control feeds with unknown levels of GM ingredients or unknown agrichemicals may have compromised the results [1].

A study has just been published which explores, for the first time, the true extent of contaminants in rodent chow.

Laboratory rats and mice are established models for testing human and environmental health. They are fed a specially-formulated, nationally-optimised feed derived from agricultural products and by-products, and hygienically housed in standardised environmental conditions.

Despite all this, and a robust genetic background, lab rats demonstrate an inexplicably wide range of life-spans. Suggested culprits include free access to food and water coupled to minimal exercise leading to obesity and ill-health, and toxic plasticisers released from cages. However, this doesn't explain why a huge variation in the level of background 'spontaneous' pathologies recorded in lab rodents has been observed at different times. For example, in one commonly used strain of lab rat, the incidence of one type of mammary tumour has varied from 13 to 62 percent, and pituitary tumours have varied from 26 to 93 percent.

This suggests a changeable, environmental cause, of which different batches of diet are the most obvious.

The rodent chow study analysed samples from 13 suppliers from 9 countries on 5 continents. It covered lab feed used in academic research, regulatory assessment and breeding companies. In particular, it applied to the external controls used in industry-sponsored research to support applications to market. In total, 262 pesticides, 4 heavy metals, 18 PCBs*, 17 dioxins*, and 22 GMOs were measured.

*Cumulative industrial toxins widespread in the environment and causing health concerns
All diets were contaminated with pesticides, heavy metals, dioxins and PCBs; 11 out of 13 samples contained GMOs (two samples from Italy were negative). All diets exceeded the acceptable daily intake for heavy metals, dioxins and PCBs. Amplified risk due to cocktail effects has not been assessed, but the authors also noted the presence of ingredients added to pesticide formulations to boost the toxicity of the active chemical.

The implications for science of so many known sources of harm in lab feed are huge, especially because:
  • pathologies will not be stable in rodents fed such a diet
  • the use of 'historical' control animals, which will clearly have been fed a different mixture of toxins and GMOs, is entirely inappropriate
  • the use of data from rodents fed varying cocktails of toxins and GMOs to set the benchmark for 'biologically meaningful' results is revealed for the scam it always was
  • the reduced sensitivity resulting from tests with compromised controls means small differences, previously dismissed, may actually be highly significant signs of disease
  • the reduced sensitivity resulting from tests with compromised controls means the huge number of test animals demanded for cancer studies may be unnecessary, and may therefore be responsible for unnecessary suffering.

Scientists seem surprisingly content to write off disease in their lab animals as an unexplained 'random', 'spontaneous' event or some genetic aberration, even when the real cause is so fundamental it could be invalidating all their research. The data raise the question of whether there's any such thing as a disease caused by tough luck or genes.

Most shocking of all is that no one's ever done any such study before. Besides invalidating key safety science, it may well be indicative of the (unmeasured) levels of multiple nasties in the human diet and how much chronic disease could be a result of them.

  • Robin Mesnage, et al., 2015, Laboratory Rodent Diets Contain Toxic Levels of Environmental Contaminants: Implications for Regulatory Tests, PLOS ONE, 2.07.15

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