The percentage of US shoppers that believe food from supermarkets is safe has dropped in the last few years, according to new research.

Although the majority of Americans feel that foods in supermarkets are safe, the percentage who feel this way has decreased to 63% from 68% over the last five years, according to market research company The NPD Group.

The latest NPD Food Safety Monitor, which has tracked food safety concerns and eating intentions in the US since 2001, surveyed 13,000 adults with the statement: “Overall, I feel that foods sold in supermarkets are safe.”

“I believe that consumers’ slipping confidence in the safety of supermarket food is less about food safety and more about supermarkets expanding foodservice operations and offering more prepared, ready-to-eat foods,” said Harry Balzer, chief industry analyst and vice president at NPD. “More food handling issues and concerns come into play when foods are prepared for you. Consumers are now extending the concerns they have about the safety of foods served at restaurants to supermarkets.”

The survey also showed that the percentage of consumers who feel that foods served at restaurants are safe has remained, on average, between 48-49% since 2004.

“Consumers are more concerned about the safety of food served in restaurants than food available from supermarkets, about a 15% point difference,” Balzer said. “However, feelings about food safety in restaurants have remained relatively unchanged whereas the number of consumers who feel confident in the safety of foods in supermarkets is declining.”

In terms of food safety concerns, salmonella, E.coli, trans fatty acids, mercury in fish/seafood, Mad Cow, high fructose corn syrup, artificial growth hormones in milk, genetically modified foods, foot and mouth disease, and meat/milk from cloned animals rank among Americans’ top food safety concerns, according to the most recent NPD Food Safety Monitor.