Don't expect to find irradiated spinach and lettuce in your supermarket any time soon, even though federal regulators have given the food industry permission to sell it.
Several hurdles will discourage immediate widespread adoption, including cost, lack of irradiation facilities, concerns about how well it will work and whether consumers will buy produce that's been irradiated to kill dangerous bugs such as E. coli.
"Right now, it's not cost-effective," says David Gombas, senior vice president of the United Fresh Produce Association. "It'll take time and money to make it practical."
The Food and Drug Administration last week started allowing foodmakers to irradiate iceberg lettuce and spinach, saying data showed no harm to consumers or the products' nutritional values. The leafy greens join a dozen other foods that can be irradiated to kill pathogens, including meat, poultry, spices and some shellfish.
But most U.S. irradiation facilities treat medical products, and only a handful are set up for food. That means processors will have to pay to ship produce hundreds of miles to be irradiated — losing precious shelf life in the process, Gombas says.
Foodmakers could build irradiation facilities. But they'd cost millions of dollars — a big bet for a technology that's been largely shunned by consumers.
"You'll see gradual adoption and early adopters … who convince others to try," says Richard Hunter, CEO of Food Technology Service, a 13-employee food-irradiation company in Florida that's considered a food-irradiation leader but which relies on medical devices for 70% of its revenue.
Historically, high radiation doses used to kill all bacteria on fruits or vegetables have produced unpalatable products, researchers say.
But testing by the U.S. Department of Agriculture has shown that treating spinach and lettuce with relatively low radiation kills 99.9% to 99.99% of E. coli and is slightly less successful against salmonella, says Brendan Niemira, a researcher at the Microbial Food Safety Research Unit of the USDA-ARS Eastern Regional Research Center in Pennsylvania.
Chlorine washes, used by bagged-salad makers to clean produce and prevent the spread of bacteria inside processing plants, typically get 90% to 99% of the bacteria, studies have shown.
Irradiation — which destroys bacteria with intense pulses of energy that disrupt its DNA — also kills bacteria that may be inside leaves, where chlorine washes aren't effective, Niemira says.
But he says the greens have also shown some softening when irradiated at doses of 1.5 Kilogray, or kGy, which is how radiation doses are measured.
Finding the right dose to kill bacteria but maintain crispness will be crucial, Hunter says. "It'll take processors awhile for them to develop their product and process," he says.
Effect of 2006 recall
Foodmakers have tested irradiation for years. Interest picked up after the 2006 E. coli outbreak in fresh spinach that killed five and sickened more than 200, says Harlan Clemmons, president of Sadex in Sioux City, Iowa.
The six-employee company irradiates feed ingredients, ground beef, spices, pet treats and some poultry. It occupies a plant built by SureBeam, formerly a leading food-irradiation firm that filed for Chapter 7 bankruptcy in 2004.