Most of the food that is supposed to be removed from the marketplace under government-monitored recalls is never recovered, posing a risk that people will get sick from eating it, congressional investigators said Wednesday.

The Government Accountability Office (search) said the Agriculture Department and the Food and Drug Administration (search) are not properly tracking recalls or acting aggressively enough to make sure unsafe food is taken off shelves.

Less than 40 percent of recalled food was returned to stores or distributors, or destroyed, the report said.

The agencies told investigators of instances in which companies were slow to disclose where they had distributed the food or provided inaccurate customer lists.

This information is vital because the agencies contact a sample of the distribution chain from these lists to verify that customers receive notice of the recall and that potentially unsafe food is removed.

Entire parts of distribution chains are overlooked because of the way the agencies select customers for sampling, the GAO found.

Two large food recalls in 2003 were linked with eight deaths and nearly 100 serious illnesses in at least 16 states, the study said.

The GAO said only 38 percent of food recalled under Agriculture Department (search) monitoring was ever recovered — or taken out of the distribution-consumer chain — in 2003, while only 36 percent of food recalled under FDA monitoring was recovered.

The report also found:

— The agencies do not know how promptly and completely companies are carrying out recalls.

— For the 10 Agriculture Department recalls examined in depth by the GAO in 2003, the department's staff averaged 38 days to complete verification checks. For the 10 FDA recalls examined, its staff averaged 31 days. These time frames exceeded the expected shelf life for some perishable foods that were recalled, such as fresh ground beef and fresh-cut bagged lettuce.

— The agencies may not be doing enough to alert people to a recall with its existing methods — mainly, press releases and Web postings — and should consider posting notices in grocery stores and telling consumers directly.

Manufacturers voluntarily recall potentially unsafe food by notifying their customers to return or destroy it. The Agriculture Department is responsible for monitoring recalls involving meat, poultry and egg products; the FDA deals with recalls for other foods.

The GAO said Congress should consider legislation requiring a company to notify the government if either agency discovers it has distributed unsafe food, and giving the agencies authority to order food recalls.

The Agriculture Department said the report was generally accurate, and procedures the department endorsed in May address most of the weaknesses in its recall program. The FDA disputed the report's findings that its procedures reduced the recovery of recalled food or caused delays, the GAO said.