Skeptic News: Does GM cause cancer?

From: Reuters

In a study that prompted criticism from other experts, French scientists said on Wednesday that rats fed on Monsanto’s genetically modified (GM) corn or exposed to its top-selling weedkiller suffered tumors and multiple organ damage.

Gilles-Eric Seralini of the University of Caen and colleagues said ra]ts fed on a diet containing NK603 – a seed variety made tolerant to dousings of Monsanto’s Roundup weedkiller – or given water with Roundup at levels permitted in the United States, died earlier than those on a standard diet.

Experts not involved in the study were highly skeptical about its methods and findings, with some accusing the French scientists of going on a “statistical fishing trip”.

The animals on the GM diet suffered mammary tumors, as well as severe liver and kidney damage. The study was published in the peer-reviewed journal Food and Chemical Toxicology and presented at a news conference in London.

The researchers said 50 percent of males and 70 percent of females died prematurely, compared with only 30 percent and 20 percent in the control group.

Monsanto was not immediately available for comment but the group has in the past repeatedly said its products are safe and there is no credible evidence of any health risk to humans or animals from consuming GM crops.

Experts asked by reporters to review the scientific paper advised extreme caution in drawing conclusions from it. The report appears to be based on a follow-up to Seralini et al.’s 2009 paper which was a statistical reanalysis of results obtained in other laboratories. The paper was heavily criticised) (see p8) by a European Food Safety Authority GMO panel for its poor methodology, in particular the panel concluded that the researchers:

  1. Make erroneous statements concerning the use of reference varieties to provide estimates of variability that allow equivalence testing to place statistically significant results into biological context as advocated by EFSA
  2. Do not use the available information concerning normal background variability between animals fed with different diets, to place observed differences into biological context
  3. Do not present results using their False Discovery Rate methodology in a meaningful way
  4. Dive no evidence to relate well-known gender differences in response to diet to claims of effects due to the respective GMOs
  5. Estimate statistical power based on inappropriate analyses and magnitudes of difference.
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