Where do chicken nuggets come from? The answer may not be straightforward following the Department of Agriculture's announcement on Friday that it hasapproved four Chinese poultry processors to begin shipping meat to the U.S.

According to The New York Times, the poultry that processors are allowed to ship will initially be restricted to cooked meat from birds raised in the U.S. But critics worry that the rules will change in the future, opening the door for poultry raised and slaughtered in China -- a country notorious for its food safety problems -- to be shipped to the U.S.

Among those critics is Tony Corbo, a senior lobbyist for the advocacy group Food and Water Watch. “This is the first step towards allowing China to export its own domestic chickens to the U.S.,” he told the Times.

Corbo has reason to be concerned; in the last months alone, Chinese police discovered an illegal food smuggling plot to sell 46-year-old chicken feet treated with bleach, a criminal ring accused of selling rat and fox meat as lamb and abnormally high levels of cadmium, a metal that can cause cancer and other illnesses, in rice sold in Guangzhou restaurants.

Also troubling, an explosion at a Chinese poultry factory in June killed at least 119 people, and concerns over avian flu remain rampant. Earlier this year, 20,000 birds were euthanized after the human death toll in China rose to six.

Unlike other meat imported to the U.S., the poultry shipped by Chinese processors will not require point-of-origin labeling. Under USDA rules, the labeling does not apply to foods that have been cooked.

"Consumers will have no way to tell if those chicken nuggets in the supermarket freezer were processed in the U.S. or in China," writes Bloomberg correspondent Adam Minter. Moreover, the USDA will not require its own regulators to supervise the processors on premises.

Point-of-origin labeling is relatively new in the U.S. (new rules went into effect and May), but has proved unpopular with meat producers. In July, industry groups filed a suit against the USDA, which charges that requiring more information about a product's origin on its label is too expensive and provides no benefit to public safety or health.

Read the USDA's full audit of the Chinese processors here.