Should there be required labeling of GMOs?

Should there be required labeling of GMOs?

via Marginal Revolution by Tyler Cowen on 9/17/12

Here is one on-the-mark take (of many):

…there have been more than 300 independent medical studies on the health and safety of genetically modified foods. The World Health Organization, the National Academy of Sciences, the American Medical Association and many others have reached the same determination that foods made using GM ingredients are safe, and in fact are substantially equivalent to conventional alternatives. As a result, the FDA does not require labels on foods with genetically modified ingredients because it acknowledges they may mislead consumers into thinking there could be adverse health effects, which has no basis in scientific evidence.

Or try the National Academy of Sciences from 2010:

Many U.S. farmers who grow genetically engineered (GE) crops are realizing substantial economic and environmental benefits — such as lower production costs, fewer pest problems, reduced use of pesticides, and better yields — compared with conventional crops, says a new report from the National Research Council.

Here is a good NYT summary Op-Ed on that report.  There is not the scientific evidence for Mark Bittman's recent evaluation that:

G.M.O.'s, to date, have neither become a panacea — far from it — nor created Frankenfoods, though by most estimates the evidence is far more damning than it is supportive.

It's the tag there that is problematic.  He doesn't offer a citation, nor has he in past columns offered convincing material to back this evaluation (you can read here for a somewhat more detailed account from Bittman; it simply minimizes benefits and does not support "by most estimates the evidence is far more damning than it is supportive").  This earlier critique of Bittman is on the mark on virtually every point.
The standards of evidence being applied here are extremely weak.  In that last Bittman link he wrote that:

…The surge in suicides among Indian farmers has been attributed by some, at least in part, to G.E. crops…

The link is to a sensationalistic Daily Mail (tabloid) story, yet that gets translated into "has been attributed by some."  In that story, the suicides were caused by indebtedness and supposedly the debts were in part caused by a desire by farmers to buy GMO crops.  In comparable terms one could write that anything one spends money on could cause suicide through the medium of indebtedness.
By the way, the Wikipedia treatment gives some more detailed citations suggesting that GMO crops are not a significant cause of farmer suicides in India.  The most careful study of the matter reports this:

We first show that there is no evidence in available data of a "resurgence" of farmer suicides in India in the last five years. Second, we find that Bt cotton technology has been very effective overall in India. However, the context in which Bt cotton was introduced has generated disappointing results in some particular districts and seasons. Third, our analysis clearly shows that Bt cotton is neither a necessary nor a sufficient condition for the occurrence of farmer suicides. In contrast, many other factors have likely played a prominent role.

I would in fact be more supportive of the GMO labeling idea if renowned food writers such as Bittman, and many others including left-wing economists, would come out and boldly proclaim the science about GMOs to their readers.  Too often the tendency is to use a "I'll try not to say anything literally incorrect, while insinuating there are big problems" method of scoring points against big agriculture.  (Another common trope is to switch the discussion to "distribution" and to suggest, either explicitly or implicitly, that a net benefit technology such as GMOs is somehow unnecessary or undesirable; dare I utter the words "mood affiliation"?)  GMO labeling is the one issue which has gained legal traction, so critics of "Big Ag" just can't bring themselves to give it up.
Bittman's whole column is about GMOs, but he gets at the important point only in his final sentence:

[With better information] We'd be able to make saner choices, and those choices would greatly affect Big Food's ability to freely use genetically manipulated materials, an almost unlimited assortment of drugs and inhumane and environmentally destructive animal-production methods.

Overuse of antibiotics and animal treatment (both cruelty and environmental issues) — now those are two very real problems, backed by overwhelming scientific evidence.  The fact that the California referendum is instead about GMOs — which have overwhelming scientific evidence for net benefit and minimal risks — is the real scandal.
It's time that our most renowned food writers woke up to that difference.  In the meantime, they are doing both us and themselves a deep disservice.