Steve Bloom, Associated Press
Several hundred supporters for consumer labeling of genetically modified foods marched from a noon rally Saturday, May 24, 2014 at the State Capitol in Olympia, Wash. to Olympia Farmers Market in hopes of raising awareness of the GMO issue.

Last month, Vermont became the first state in the union to require genetically-modified organisms in foods to receive a packaging label. Around the same time, California rejected a mandatory GMO-labeling bill for the second time. There have been other sporadic local movements and protests against GMO foods.

Indeed, the use of science to enhance agricultural output has been attacked on nearly every front for quite some time. There have been patent and licensing disputes on the seeds from which crops are grown. But while there has been no legitimate suggestion that such GMO foods are unsafe, other concerns about food supply practices may have some merit.

Recent studies about crops that are resistant to Monsanto’s widely use weed-killer Roundup have raised a disconcerting possibility. Glyphosate, the active ingredient in the weedkiller, is not by itself harmful: humans seem to be able to ingest it without ill effect. But the proliferation of glyphosate and related chemicals in our environment may lead to unintended consequences.

Farmers seek simplified processes. Anything that helps them to become more efficient with their time is very valuable. That’s led to the development of herbicide-resistant strains of crops, bio-engineered to permit farmers to spray herbicide on the their fields to kill weeds with little worry about reducing crop yield.

On the other hand, increasing occupational exposure to glyphosates requires attention to how they interact with inert, non-weedkilling chemicals. Some researchers have suggested that high levels of glyphosates interact with the human stomach and intestines in unpredictable and potentially damaging ways.

Scientific American published an article discussing research on the inert ingredients in herbicides like Roundup in 2009. And an article published in the International Journal of Environmental Research and Public Health in April 2014 supported a link between exposure to glyphosate herbicides and Non-Hodgkins Lymphoma.

The glyphosates by themselves seem to have little to no effect on human cells. Yet the inert ingredients that don’t harm bio-engineered crops do affect human cells, as well as many kinds of bacteria — including bacteria types critical to our gastro-intestinal health.

These recent studies will require further examination. Just as it is incumbent upon health professionals not to overprescribe antibiotics, we should similarly ensure that the unintentional effects of farming practices reliant upon GMOs do not become deleterious to human health.