A new study has found ambiguous dates on packages could be behind high levels of food waste in the U.S.

"People eat a lot less of their refrigerated food than they expect to, and they're likely throwing out perfectly good food because they misunderstand labels," said Brian Roe, the study's senior author at The Ohio State University.

"No one knows what 'use by' and 'best by' labels mean and people think they are a safety indicator when they are generally a quality indicator," Roe said. There's a proposal currently before Congress to prescribe date labeling rules in an effort to provide some clarity.

Under the proposal, "Best if used by" would, as Roe puts it, translate to "Follow your nose". And "Use by" would translate to "Toss it."

The study also found that people who cleaned out their refrigerators more often wasted more food. In addition, those who check nutrition labels frequently waste less food. And furthermore, younger households were more likely to waste than older households.

A series of bad behaviors leads to food waste

Household food waste happens at the end of the line of a series of behaviors. That is according to Megan Davenport, who led the study at Ohio State's Department of Agricultural, Environmental and Development Economics.

"There's the purchasing of food, the management of food within the home and the disposal, and these household routines ultimately increase or decrease waste," she said.

"We wanted to better understand those relationships, and how individual products -- including their labels -- affect the amount of food waste in a home."

The researchers asked about fruits, vegetables, meats and dairy -- in particular how much was there and how much people expected to eat. Then they followed up about a week later to find out what really happened.

The surveys also asked about a variety of factors that may have influenced decisions to toss food, including date labels, odor, appearance and cost.

An estimated 43% of food waste is due to in-home practices - as opposed to waste that happens in restaurants, grocery stores and on the farm. These makes individuals the biggest contributors. They're also the most complicated group in which to drive change, given that practices vary significantly from home to home, Roe said.

"We wanted to understand how people are using the refrigerator and if it is a destination where half-eaten food goes to die," he said.

"That's especially important because much of the advice that consumers hear regarding food waste is to refrigerate (and eat) leftovers; and to 'shop' the refrigerator first before ordering out or heading to the store."

Identifying policy opportunities

Roughly one-third of the food produced worldwide for human consumption -- approximately 1.3 billion tons annually -- is lost or wasted, according to the Food and Agriculture Organization of the United Nations. The organization estimates the annual dollar value of that waste at US$680bn in industrialized countries and US$310bn in developing countries.

This study looked at refrigerated food because that's where most perishable foods are found in a household and where the bulk of efforts to encourage people to waste less food have been focused.

In addition to better understanding food waste patterns, the researchers wanted to help identify opportunities to design policy or public messaging that will work in driving down waste.

"Our results suggest that strategies to reduce food waste in the U.S. should include limiting and standardizing the number of phrases used on date labels, and education campaigns to help consumers better understand the physical signs of food safety and quality," Davenport said.

The study will appear in the November print issue of the journal Resources, Conservation & Recycling.