Shoppers have long been willing to pay a premium for organic food. But how much is too much?

Rising prices for organic groceries are prompting some consumers to question their devotion to food produced without pesticides, chemical fertilizers or antibiotics. In some parts of the country, a loaf of organic bread can cost $4.50, a pound of pasta has hit $3, and organic milk is closing in on $7 a gallon.

“The prices have gotten ridiculous,” said Brenda Czarnik, who was shopping recently at a food cooperative in St. Paul.

Food prices in general have been rising, but organic food lagged somewhat behind last year because of a temporary glut of organic milk and other factors. Some grocery chains adopted private-label organic products, which are cheaper than brand products, while others hesitated to raise already high organic prices.

In recent months, however, these factors have been giving way to cost pressures in the industry. On grocery shelves across the nation, sharp price increases are taking hold.