For instance, produce from the Dominican Republic was stopped 813 times last year, usually for containing traces of illegal pesticides. Candy from Denmark was impounded 82 times.

By comparison, Chinese seafood was stopped at the border 331 times during the last year.

“The reality is, this is not a single-country issue at all,” said Carl R. Nielsen, who resigned from the Food and Drug Administration in 2005, after 28 years. His last job was director of the division of import operations and policy in the agency’s Office of Regulatory Affairs. “What we are experiencing is massive globalization,” he said.

The F.D.A. database does not necessarily capture a full and accurate picture of product quality from other countries. For one thing, only one year of data is available on the agency’s Web site, and F.D.A. officials declined to provide more data without a formal Freedom of Information request, a process that can take months, if not years.

In addition, the F.D.A. inspects only about 1 percent of the imports that fall under its jurisdiction. So the agency may miss many of the products that are contaminated or defective. The F.D.A. database also fails to disclose the quantity of products that are refused, so it is impossible to know whether just a box of cucumbers was refused or a shipload.

In cases of recurrent problems, the F.D.A. may issue an import alert, which leads to additional scrutiny at the border. Last month, for instance, the F.D.A. issued not only the import alert for the Chinese fish, but also import alerts for Mexican cantaloupes and basmati rice from India, among others.