Truth: Studies that claim safety for GM crops are more likely to be industry-linked and therefore biased

Myth at a glance

GM proponents claim that those who claim GM foods are unsafe are being selective with the data, since many other studies show they are safe.

But two comprehensive reviews of the scientific literature show that industry-linked studies are more likely to conclude that the GM food being tested is safe, whereas independent studies are more likely to raise concerns.

A comprehensive review of studies on the health risks and nutritional value of GM crops found that if a study on GMOs involves an industry scientist, it will invariably find no problem with the GMO.

This pattern of industry bias and advocacy science has been well documented in the case of other products, such as tobacco and pharmaceutical drugs.

The bias of industry-sponsored or industry-linked studies on the safety of hazardous products is well documented. Each time industry-linked studies are compared with studies on the same product from the independent (non-industry-linked) scientific literature, the same verdict is reached: industry studies are more likely to conclude that the product is safe.

The best known example is tobacco industry studies, which successfully delayed regulation for decades by manufacturing doubt and controversy about the negative health effects of smoking and passive smoking.1 Studies sponsored by the pharmaceutical and mobile phone industry have also been shown to be more likely to portray their products in a favourable light than non-industry-funded studies.2,3,4

The case of GM crops is no different. Reviews of the scientific literature on the health risks of GM foods demonstrate that industry-linked studies are more likely to conclude that the GM food tested is safe, whereas independent studies are more likely to raise concerns:

  • A review of 94 published studies on health risks and nutritional value of GM crops found that they were much more likely to reach favourable conclusions when the authors were affiliated with the GM industry than when the authors had no industry affiliation. In the studies where there was such a conflict of interest, 100% (41 out of 41) reached a favourable conclusion on GMO safety. The remaining 53 papers, in which none of the authors had professional ties to the biotech industry, were split: 39 concluded safety, 12 found problems, and two had neutral conclusions.5 This was a highly statistically significant difference: the probability of it happening by chance was less than one in 1,000. This finding suggests that if a study on GMOs involves an industry scientist, it will invariably find no problem with the GMO.
  • A literature review of GM food safety studies found about an equal number of research groups suggesting that GM foods were safe and groups raising serious concerns. However, most studies concluding that GM foods are as nutritious and safe as non-GM counterparts were performed by the companies responsible for developing the GMO or associates.6

In spite of the fact that industry-linked studies are biased in favour of conclusions of safety, approvals for GM crops are based solely on industry studies.

“In a study involving 94 articles selected through objective criteria, it was found that the existence of either financial or professional conflict of interest was associated [with] study outcomes that cast genetically modified products in a favourable light.” – Johan Diels, CBQF/Escola Superior de Biotecnologia da Universidade Católica Portuguesa, Portugal, and colleagues5

Conclusion

A comprehensive review of the scientific literature on the health risks and nutritional wholesomeness of GM foods found that studies in which authors had a financial or professional conflict of interest with the GMO industry were more likely to conclude that the GMO was as safe and nutritional as the non-GM food tested.

References

  1. Michaels D. Doubt is Their Product: How Industry’s Assault on Science Threatens Your Health. Oxford University Press; 2008.
  2. Lexchin J, Bero LA, Djulbegovic B, Clark O. Pharmaceutical industry sponsorship and research outcome and quality: systematic review. Br Med J. 2003;326:1167. doi:10.1136/bmj.326.7400.1167.
  3. Baker CB, Johnsrud MT, Crismon ML, Rosenheck RA, Woods SW. Quantitative analysis of sponsorship bias in economic studies of antidepressants. Br J Psychiatry. 2003;183:498–506.
  4. Huss A, Egger M, Hug K, Huweiler-Müntener K, Röösli M. Source of funding and results of studies of health effects of mobile phone use: Systematic review of experimental studies. Environ Health Perspect. 2007;115:1–4.
  5. Diels J, Cunha M, Manaia C, Sabugosa-Madeira B, Silva M. Association of financial or professional conflict of interest to research outcomes on health risks or nutritional assessment studies of genetically modified products. Food Policy. 2011;36:197–203.
  6. Domingo JL, Bordonaba JG. A literature review on the safety assessment of genetically modified plants. Env Int. 2011;37:734–742.