“The majority of those crops are now GMO,” Jaffe noted.
Two other GMO crops -- apples and potatoes -- have also been approved for sale but are not yet commercially available. And several other types of produce are now winding their way through testing with the U.S. Food and Drug Administration, the U.S. Department of Agriculture or some other governmental agency, Jaffe said.
For example, a new pink pineapple variety being developed in Costa Rica by Del Monte Fresh Produce, contains an over-expressed a gene from a pineapple and a tangerine. Some of its other genes have been silenced and its flowering process has been altered. All this genetic fiddling has produced a fruit with rose-colored flesh that is high in the cancer-fighting chemical lycopene.
Humans have been genetically modifying their food for centuries through techniques like hybridization and selective breeding, Pamela Ronald, a plant scientist with the University of California, Davis, pointed out.
“Modern genetic alteration is different in that it splices genes from another species into another to produce some beneficial trait,” she said.
But the benefits of this DNA manipulation can sometimes be offset by unforeseen negatives, Jaffe said. In some cases they might accidentally introduce an allergen or they might harm the environment, he said.
Testing for GMO products is currently voluntary, according to an FDA spokeswoman.
“Although the consultation process is voluntary, compliance with the law is mandatory; it is the manufacturer's responsibility to ensure that the food products it offers for sale are safe and otherwise comply with applicable requirements,” the spokeswoman said in a statement to ABC News.
GMO plants should be evaluated on a case-by-case basis, Ronald said.
“With any kind of breeding, there is a possibility of unintended consequences,” she said. “That is always a risk that scares people but it has to be put in perspective -- the risk is no different than for other type of crop.”
If approved, the Del Monte Fresh pineapple could be sold but not grown in the U.S. The company has said the fruit is produced in a way that prevents seed production or pollination, reducing the chances it could cause harm to the environment.