A recall of frozen tater tots has expanded after federal officials warned that hundreds of thousands of pounds could contain pieces of plastic.

The U.S. Food and Drug Administration (FDA) said the expanded recall now covers about 648,000 pounds of frozen tater tots made by McCain Foods at a facility in Idaho.

The recall began last month and originally involved some Ore-Ida and Sysco Imperial potato products. The new FDA notice adds more bulk tater tot products made for food service use.

The frozen potatoes may contain “clear, hard plastic fragments,” the FDA said.

These pieces could pose a choking risk or cause injuries to the mouth or throat if eaten. So far, the agency says no injuries have been reported.

Most of the recalled products were sent to food service vendors such as restaurants and schools, not sold in grocery stores. That limits how many people may have been exposed, the FDA stated.

The newly added items include more than 21,500 cases of Ore-Ida Tater Tots Shaped Potatoes. Each case weighs roughly 30 pounds and contains six five-pound bags. The recall also includes 67 cases of Sonic-branded tater tots, packaged the same way.

The affected products were shipped to vendors in 28 states, People Magazine reported: Alaska, Arkansas, Alabama, Arizona, California, Colorado, Florida, Georgia, Hawaii, Idaho, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Mexico, Nevada, Oklahoma, Ohio, Oregon, Pennsylvania, Texas, Utah, Washington and Wisconsin.

The agency classified the recall as Class II. That means eating the product could cause short-term or reversible health effects, but serious harm is not likely.

Anyone with questions about the recall can visit the FDA’s recall website or contact McCain Foods directly at 877-804-6198 for information about refunds or disposal.