Several points made by Phyllis Kahn ("I support labeling, but not for the most-cited reasons," Aug. 26) require discussion. This debate is not between activists and "agricultural scientists," but between activists and every national food safety authority, every national health authority and every national academy of science. Every one of these organizations supports the safety of genetically engineered (GE) crops (aka GMOs) and derived foods. And yes, "agricultural" scientists agree with all of these organizations.

Kahn wrote of there being " … most likely no major difference in the health and safety of the two different products." Interesting reservations, considering that 20 years of producing commercial GE crops and over 3 trillion meals consumed containing ingredients derived from GE crops, and there is not a single documented case of harm.

Further, 30-plus years of research by global food safety and environmental authorities have produced no evidence of any unique risk from GE crops or the derived food.

Kahn continues: "Even if one believes that dairy inspections are sufficiently rigorous …," and yet she presents zero evidence of anything to the contrary. Food safety science does not work with "beliefs" but with data. And the data are very clear that there are no antibiotics in the milk supply, according to state and/or federal regulators. Every cow that has to be treated with antibiotics is always removed from the milk production cycle. Perhaps Kahn could visit a local dairy farm and speak with the farmers to learn more.

Since the dawn of life on Earth, organisms have developed resistance to deleterious compounds they were exposed to. To suggest that highly trained scientists would say "it was highly unlikely that weeds would become resistant" to one seems very unlikely. Perhaps the author can supply evidence in a later op-ed. I am not quite sure what Kahn means when she claims "resistance was easily transferred," as the DNA of the GE crops most definitely did not transfer to the resistant weeds to give them resistance. As throughout the history of life on Earth, the weeds evolved resistance to the herbicide they were exposed to. The number of Roundup-resistant weeds pales in comparison to the number of weeds resistant to other herbicides not used directly with GE crops.

I will concede that better stewardship is needed by farmers who choose to use herbicide-tolerant crops (both GE and non-GE) in order to reduce the development of resistance.

If Kahn is worried about the environmental impact of GE crops, she should read the National Academy of Sciences' 2010 report "The Impact of Genetically Engineered Crops on Farm Sustainability in the United States." It stated: "In general, the committee finds that genetic-engineering technology has produced substantial net environmental and economic benefits to U.S. farmers compared with non-GE crops in conventional agriculture."

Of the 64 countries that label food for ingredients derived from GE crops, almost half are in Europe, and it is very clear that position was adopted to erect nontariff trade barriers to North American products. Countries that trade mainly with Europe have followed suit. A couple of points here: Europe imports 40 million tons of feed from GE crops each year, but meat from animals fed these GE crops is exempt from GE labeling. Also, Europe exempts beer, wine and cheese (Europe makes a lot of these products) because these products are made "with" and not "from" ingredients derived from GE crops like those in North America.

If Kahn wants to vote for GE-specific food labels, she should explain to her constituents that it will raise the cost of their food, likely by about 10 percent. Europe admits that at least part of its higher food costs is a direct result of its GE food-labeling policies.

I would like to close by asking why the present system of labeling with voluntary non-GMO and organic labels, which already give choice to consumers who want to avoid food ingredients derived from GE crops at no extra cost, is not the better option?

Robert Wager is a technician in the biology department at Vancouver Island University in British Columbia.