For many in America, food waste is a way of life: a discarded apple here, a half-eaten dinner plate there. But just how much food do Americans waste, and why? The Washington Post’s Roberto A. Ferdman reports that new research sheds light on the dirty little habit that squanders over 30 percent of the country’s food supply and costs $161.6 billion a year, a habit driven in part by fear of food poisoning and a desire to eat only the freshest foods.

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Ferdman writes that when public health researchers from Johns Hopkins University surveyed Americans about their feelings on food waste, they found that “Americans are pretty picky about what gets to stay in their refrigerators.” The survey, which was conducted online and covered a nationally representative sample of 1,010 adults, asked questions about the things that motivate people to keep and throw out food from their refrigerators.

65 percent of respondents say they throw food out due to worries about food poisoning, while 60 percent say they only want to eat the freshest foods. A smaller amount (41 percent and 35 percent, respectively) reported that they compost food or know it breaks down in a landfill, “so it doesn’t bother me.” Only 15 percent of respondents said they don’t have time to prevent food waste.

On the other hand, respondents seemed relatively motivated to waste less food — but not for the reasons you might think. People were most motivated to reduce food waste due to desires to save money, manage their households efficiently, and set an example for their children. But regardless of the fact that food waste causes a significant environmental impact and only a fraction of food waste is composted, less than half of respondents thought it was important to reduce food waste for environmental reasons.

These results show the cognitive dissonance at the heart of the food waste problem. In a release about her research, Roni Neff, who lead the study, notes that “Americans perceive themselves of wasting very little food, but in reality, we are wasting substantial quantities.”

Neff hopes the results will help educators, policymakers and businesses pinpoint changes — like highlighting the economic costs of food waste — that are actually likely to reduce waste. But perhaps the most effective strategy, write Neff and her team, could be honing messages about food safety and freshness so that Americans get less grossed out by the potential of food poisoning to begin with.