Stuart Bradford

How much food does your family waste?

A lot, if you are typical. By most estimates, a quarter to half of all food produced in the United States goes uneaten — left in fields, spoiled in transport, thrown out at the grocery store, scraped into the garbage or forgotten until it spoils.

A study in Tompkins County, N.Y., showed that 40 percent of food waste occurred in the home. Another study, by the Cornell University Food and Brand Lab, found that 93 percent of respondents acknowledged buying foods they never used.

And worries about food safety prompt many of us to throw away perfectly good food. In a study at Oregon State University, consumers were shown three samples of iceberg lettuce, two of them with varying degrees of light brown on the edges and at the base. Although all three were edible, and the brown edges easily cut away, 40 percent of respondents said they would serve only the pristine lettuce.

In his new book “American Wasteland: How America Throws Away Nearly Half of Its Food” (Da Capo Press), Jonathan Bloom makes the case that curbing food waste isn’t just about cleaning your plate.

“The bad news is that we’re extremely wasteful,” Mr. Bloom said in an interview. “The positive side of it is that we have a real role to play here, and we can effect change. If we all reduce food waste in our homes, we’ll have a significant impact.”

Why should we care about food waste? For starters, it’s expensive. Citing various studies, including one at the University of Arizona called the Garbage Project that tracked home food waste for three decades, Mr. Bloom estimates that as much as 25 percent of the food we bring into our homes is wasted. So a family of four that spends $175 a week on groceries squanders more than $40 worth of food each week and $2,275 a year.

And from a health standpoint, allowing fresh fruits, vegetables and meats to spoil in our refrigerators increases the likelihood that we will turn to less healthful processed foods or restaurant meals. Wasted food also takes an environmental toll. Food scraps make up about 19 percent of the waste dumped in landfills, where it ends up rotting and producing methane, a greenhouse gas.

A major culprit, Mr. Bloom says, is refrigerator clutter. Fresh foods and leftovers languish on crowded shelves and eventually go bad. Mr. Bloom tells the story of discovering basil, mint and a red onion hiding in the fridge of a friend who had just bought all three, forgetting he already had them.

“It gets frustrating when you forget about something and discover it two weeks later,” Mr. Bloom said. “So many people these days have these massive refrigerators, and there is this sense that we need to keep them well stocked. But there’s no way you can eat all that food before it goes bad.”

Then there are chilling and food-storage problems. The ideal refrigerator temperature is 37 degrees Fahrenheit, and the freezer should be zero degrees, says Mark Connelly, deputy technical director for Consumer Reports, which recently conducted extensive testing on a variety of refrigerators. The magazine found that most but not all newer models had good temperature control, although models with digital temperature settings typically were the best.

Vegetables keep best in crisper drawers with separate humidity controls.

If food seems to be spoiling quickly in your refrigerator, check to make sure you’re following the manufacturer’s care instructions. Look behind the fridge to see if coils have become caked with dust, dirt or pet hair, which can interfere with performance.

“One of the pieces of advice we give is to go to a hardware store and buy a relatively inexpensive thermometer,” Mr. Connelly said. “Put it in the refrigerator to check the temperature to make sure it’s cold enough.”

There’s an even easier way: check the ice cream. If it feels soft, that means the temperature is at least 8 degrees Fahrenheit and you need to lower the setting. And if you’re investing in a new model, don’t just think about space and style, but focus on the refrigerator that has the best sight lines, so you can see what you’re storing. Bottom-freezer units put fresh foods at eye level, lowering the chance that they will be forgotten and left to spoil.

Mr. Bloom also suggests “making friends with your freezer,” using it to store fresh foods that would otherwise spoil before you have time to eat them.

Or invest in special produce containers with top vents and bottom strainers to keep food fresh. Buy whole heads of lettuce, which stay fresher longer, or add a paper towel to the bottom of bagged lettuce and vegetables to absorb liquids. Finally, plan out meals and create detailed shopping lists so you don’t buy more food than you can eat.

Don’t be afraid of brown spots or mushy parts that can easily be cut away.

“Consumers want perfect foods,” said Shirley Van Garde, the now-retired co-author of the Oregon State study. “They have real difficulty trying to tell the difference in quality changes and safety spoilage. With lettuce, take off a couple of leaves, you can do some cutting and the rest of it is still usable.”

And if you do decide to throw away food, give it a second look, Mr. Bloom advises. “The common attitude is ‘when in doubt, throw it out,’” he said. “But I try to give the food the benefit of the doubt.”

A version of this article appeared in print on Nov. 2, 2010, on page D5 of the New York edition of The Times.