Many shoppers are being especially vigilant about what they buy as food-tampering incidents in Calgary mount.

Four new cases of food tampering arose this week in grocery stores across the city, bringing the total to 11 cases in nine stores since January. Small shards of metal have been found in products ranging from ground beef to oranges.

"We are just going to have to be more careful to what we purchase and what we're handling, and kind of make sure that it's safe to eat before we ingest it," said Loren Lopez, who was shopping at a Safeway store.

Shoppers said they can't understand what's going on.

"I think it's crazy, whoever is doing it," one said. "I also am a little more careful about what I buy."

Some consumers said that despite the food-tampering cases, they'll change little about how they shop.

"You can't live in fear," one said.

Believing a group of copycats is at work, Calgary police have decided to stop holding news conferences on the topic for fear media attention is fuelling more cases.

Police continue to urge shoppers to thoroughly inspect store-bought food to ensure products are free of foreign objects.