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By Michael Hansen

TIME AND again, national surveys indicate that upwards of 90 percent of consumers want foods produced using genetically modified organisms (GMOs) to be labeled as such — in fact, a recent Consumer Reports survey placed the number at 92 percent. Of course, the right of everyone to know what they are eating is largely self-evident.

But, from a scientific standpoint, is genetically engineered food really different enough to warrant a special label?

First developed in the 1970s, genetic engineering techniques allow genetic material to be moved between living things in ways that can never occur in nature.

As an extreme example, human genes have been moved into rice plants to make the plants produce certain proteins normally found in breast milk. More routinely, most genetically engineered crops on the market contain genes introduced from bacteria and viruses.

A gene introduced into salmon from an eel-like fish called an ocean pout enables engineered salmon to reach market size significantly faster than nonengineered salmon.

Consumers have come to expect that their food will be labeled if it is frozen, made from concentrate, irradiated, or homogenized — and the law has delivered on that expectation.

All labeling, including required printing of ingredients, additives, and nutritional content, exists to give consumers the power to make free and informed choices about what they are putting in their bodies.

Consumers have long prized the transparency that allows them to make a clear choice between, say, frozen and unfrozen corn. Is it too much to ask that they are provided with the same level of transparency when choosing between traditional corn and corn that has been genetically engineered to express a toxin normally found in bacteria — a much more significant distinction?

Transparency is a value unto itself, but there are other reasons why consumers might want to know if their food has been genetically engineered.

The vast majority of soybean, corn, canola, and sugar beets have been engineered to tolerate being sprayed with the weed killer glyphosate.

Between 1996, when GMO food crops were first allowed in US agriculture, and 2012, glyphosate use increased from roughly 20 million pounds to 280 million pounds, making it by far the most widely-used pesticide in US agriculture. Last year, the World Health Organization’s International Agency for Research on Cancer unanimously concluded that glyphosate, previously thought by pesticide regulators to be largely benign, was “probably carcinogenic to humans.

Widespread herbicide use on genetically engineered crops throughout the Corn Belt also appears primarily responsible for a large decline in monarch butterfly populations, due to wiping out most of the milkweed on which they depend.

These potentially severe health and environmental impacts are reasons why consumers want to know whether their food has been genetically engineered.

Despite the touted potential for GMO crops to produce more nutritious foods or to feed the world, little has materialized so far.

Genetically engineered crops have not significantly increased yields beyond what conventional breeding or improvement in other agricultural practices have attained, and there are far more cost-effective and productive ways to address world hunger.

The US Senate acted in the clear interest of consumers when it voted not to consider a bill that would have preempted Vermont’s mandatory GMO labeling law — a decision that honored Justice Louis Brandeis’s 1932 observation that “a single courageous state may . . . serve as a laboratory” of democracy. We at Consumer Reports urge Massachusetts to meet the needs of its citizens by requiring labels on genetically engineered food in the Commonwealth.

Michael Hansen is a senior scientist at Consumers Reports.

Boston Globe