Those for and those against the mandatory labeling of foods with ingredients developed through bioengineering squared off at a House subcommittee hearing on Dec. 10 called to draw attention to H.R. 4432, the Safe and Accurate Food Labeling Act of 2014. The hearing held by the health subcommittee of the House Committee on Energy and Commerce was titled “Examining F.D.A.’s role in the regulation of genetically modified food ingredients,” but all of the witnesses came prepared to discuss H.R. 4432.

The Safe and Accurate Food Labeling Act was introduced by Representatives Mike Pompeo of Kansas, a Republican, and G.K. Butterfield of North Carolina, a Democrat, to create a mandatory pre-market safety review of all crops containing bioengineered traits and destined for use in the food supply. The bill affirmed the Food and Drug Administration would be the responsible agency. But labeling of bioengineered ingredients would remain voluntary, and the national law would preempt any state or local laws requiring mandatory labeling, such as Act 120, which was signed into law by the State of Vermont earlier this year.

Representative Joseph R. Pitts of Pennsylvania, chairman of the health subcommittee, said in opening the hearing, “Food labeling is a matter of interstate commerce and is, therefore, clearly a federal issue that rightfully resides with Congress and the F.D.A. I’m concerned that a patchwork of 50 separate state labeling schemes would be impractical and unworkable. Such a system would create confusion among consumers and result in higher prices and fewer options.”

Michael M. Landa, director of the F.D.A.’s Center for Food Safety and Applied Nutrition, explained what he asserted was the F.D.A.’s rigorous food safety evaluation of bioengineered foods.

“As a result of these premarket consultations, we are confident that genetically engineered foods in the U.S. marketplace today are as safe as their conventional counterparts,” he said.

Mr. Landa said the F.D.A. stands by its 1992 policy statement and studies conducted since that indicated the agency had no basis to conclude that foods derived from new plant varieties using genetic engineering techniques, as a class, differed from other foods in any meaningful way or posed any different or greater safety concern than foods developed by traditional plant breeding. Therefore, there was no basis in current law for the F.D.A. to require mandatory labeling. At the same time, the F.D.A., Mr. Landa said, appreciated that many consumers are interested in knowing whether their food was produced using bioengineering, and the agency has been supportive of voluntary labeling.

Representative Kate Webb, assistant majority leader in the Vermont House of Representatives, speaking in a personal capacity, said, “I was the lead sponsor of Act 120, a law that simply gives consumers the right to know if the food they purchase in Vermont is genetically engineered. This law is at risk should H.R. 4432 become law.”

Ms. Webb asserted, “There is nothing in our law that restricts farmers, producers, manufacturers, or retailers from producing or selling genetically engineered products. Business and farming will go on as business and farming does, responding to the market.

“Most people would greatly prefer a national G.E. (genetically engineered) labeling system and national rules designed to restrict misleading claims of products being ‘natural.’ To date, neither the current administration nor this Congress has acted to inform and protect consumers with this labeling.

“Unfortunately, H.R. 4432 does not create a national mandatory G.E. labeling system. Instead, H.R. 4432 codifies the broken voluntary G.E. labeling system and robs states like Vermont of the ability to inform and respond to our citizens who need this information ... I urge you to oppose H.R. 4432 and to support mandatory labeling of products produced through genetic engineering.”

Thomas W. Dempsey Jr., president and chief executive officer, Snack Food Association, testified, “Absent a federal G.M.O. solution, manufacturers will have essentially three options in order to comply with state labeling laws: order new packaging for products, reformulate products so that no labeling is required, or halt sales to that state. Each option is difficult, costly, time-intensive, and at worst, could eliminate jobs and consumer choice in the marketplace.”

Mr. Dempsey described what difficulties and costs might arise through the entire food chain — from the producer on the farm and the secondary handlers such as elevators who store and transport crops, to the manufacturers, distributors and retailers of food and the consumers — should food have to be manufactured, packaged and labeled to meet the requirements of even one state’s mandatory labeling law, such as Vermont’s.

“The S.F.A. does not have a single member company that manufactures, distributes and sells in just one state making a state labeling law incredibly complex to deal with,” Mr. Dempsey said. “Multiply the challenges I’ve presented here for compliance with Vermont’s Act 120 times five, or 10 or even 25 states and you place an insurmountable burden on our food supply chain and add significant increased cost to our consumers.”

Mr. Dempsey said the S.F.A. supported H.R. 4432, “which eliminates the current proposed patchwork of state and local G.M.O. labeling laws by creating one federal G.M.O. standard which eliminates confusion, advances food safety, and provides much needed consistency for manufacturers.”