Sheldon Krimsky, Tufts University Professor of Urban & Environmental Policy & Planning, recently published an excellent and data-laden analysis of GMO health risks:

Krimsky, Sheldon. “An Illusory Consensus behind GMO Health Assessment.” Science, Technology & Human Values (2015): 0162243915598381.

Certain prominent scientists and policymakers claim there is a scientific consensus on GMO safety and call anyone whose opinions differ “anti-science” or a “GMO denier.” Such advocates believe “that genetically modified crops currently in commercial use and those yet to be commercialized are inherently safe for human consumption and do not have to be tested.”

Krimsky uses several methods to critically assesses this claim of a scientific consensus. He first identifies 8 scientific reviews of GMO health effects and finds that each reaches different conclusions on safety. Krimsky then discusses the widely divergent concerns about GMO health risks expressed by different professional bodies. He points out that differing opinions on GMO safety can in part be attributed to differences in the body of research selected for review. However, he also identifies other factors.

Some of the disagreement over GMO health risks clearly arises from personal or institutional conflicts of interest (COI). The authors of one review of COI and GMOs found that “without a conflict of interest there was a 23 percent chance of reaching an unfavorable conclusion and with a COI there was only a 2 percent chance.”

Many of the reviews themselves point out the paucity of published data assessing GMO health risks. Others note that each GMO must be analyzed for risk independently, on a “case by case” basis, as every independently derived GMO is unique. Finally, Krimsky identifies and discusses the findings of 26 scientific studies that found GMO health risks. He also covers in depth the cases of two respected and productive scientists, Arpad Pusztai and Gilles-Eric Seralini, who published findings of harm from GMOs. As was the case for Pusztai and Seralini, such research findings are frequently assessed in a biased manner and the researchers themselves may be personally attacked and heavily penalized. The general lack of research on GMO health effects, therefore, may may be due in part to the current scientific and media environment which is clearly hostile to findings that GMOs cause health problems.

An Illusory Consensus behind GMO Health Assessment” is a well-documented and clearly-presented paper that addresses several important issues (1) scientific risk assessment of GMOs (2) the impact of conflicts of interest on science and (3) how to interpret research indicating GMOs harm health. None of his findings support the claim that GMOs are safe and should be unregulated. Neither do they support the claim that there is a scientific consensus on GMO safety.

Further reading:

Landrigan, Philip J., and Charles Benbrook. “GMOs, Herbicides, and Public Health.” New England Journal of Medicine 373.8 (2015): 693-695.
Hilbeck, Angelika, et al. “No scientific consensus on GMO safety.” Environmental Sciences Europe 27.1 (2015): 4.
Latham, Jonathan “Fakethrough! GMOs and the Capitulation of Science Journalism.” Independent Science News January 2014.