In the wake of the Senate’s defeat of legislation that would have preempted state-mandated Genetically Engineered ingredient labeling on food products, a new trend is emerging, as one food manufacturer after another announces that they will voluntarily label bioengineered ingredients contained in their national food product lines. The chain reaction began less than two weeks ago, with General Mills’s announcement that it will label all its products in compliance with Vermont’s law. That announcement was followed by similar statements from Mars and Kellogg’s last Monday and by ConAgra Foods the following day.

The four food giants join Campbell Soups, which was the only major food company that had already planned to institute GE labeling before the Senate vote that took place on March 16th. These national brands are labeling their products with GE information because they have said it’s neither feasible to create different labels for different states nor prudent to stop selling their products in Vermont. Despite these recent decisions, however, all five companies have made clear that they support a Federal labeling standard, and all but Campbell Soups opposes mandatory GE ingredient labeling.

Even as these companies react to Vermont’s law, which goes into effect on July 1st, the pressure to create a Federal standard is mounting. Agriculture Committee Secretary Tom Vilsack has been reiterating in recent weeks that without a national standard, a patchwork of state laws could develop – increasing the costs of compliance for businesses as well as the retail cost of food for American consumers.  (Not all food companies are large, national brands that have the financial ability to update the labels for each and every product line, so for some small businesses, these types of significant labeling revisions may be extremely burdensome.) And at least the first part of Secretary Vilsack’s prediction appears to be coming true. Massachusetts is on the cusp of requiring GE labeling, while Connecticut and Maine are considering removing from  their existing labeling laws the conditional clauses that require neighboring states to enact similar GE labeling requirements before those laws become effective.

Against this backdrop, some observers expect that the Senate may feel compelled to reconsider the GE labeling bill it rejected earlier this month. However, when asked about that possibility, Senator Chuck Grassley (R-IA) dismissed it, saying that the Senate probably will not pass a preemptive GE labeling bill before summer. If the Senator is right, more of the country’s large food manufacturers may soon implement voluntary GE labeling, as Vermont’s law, at least temporarily, could set a new standard for food ingredient disclosures.

Sam Rothbloom is co-author of this article.