It is a frightening picture: beef contaminated with toxic heavy metals, pesticides and antibiotics making its way into the nation's supermarkets.
Phyllis K. Fong, the Agriculture Department's inspector general, looked at how beef is tested for harmful substances.
According to her new report, inspectors charged with checking cattle for disease and meat for contaminants were, "unable to determine if meat has unacceptable levels of... potentially hazardous substances [and do] not test for pesticides... determined to be of high risk."
The inspectors also failed to test beef for 23 pesticides, the report says.
The study -- entitled the National Residue Program for Cattle Audit Report -- says there are no standards for how much of certain dangerous substances, such as copper and highly toxic dioxin, is too much for someone to eat. As a result, meat containing these substances has gotten into the nation's food supply, it finds.
The report says the health danger to people who eat this beef is a "growing concern," and calls for better coordination among the USDA Food Safety and Inspection Service, the Environmental Protection Agency and the U.S. Food and Drug Administration to ensure the safety of the country's meat supply.
"When it comes to this particular issue of these foreign chemicals, pollutants, antibiotics, things like that -- they haven't been doing enough, that's what's clear," says Patty Lovera of Food & Water Watch, a consumer advocacy group.
The audit report, which took place in 2007 and 2008, cited instances when inspectors found beef containing excessive levels of contaminants, but declined to recall it.
"I think the thing that was most alarming was when lab tests were failed, there was no real concerted effort to recall the failed supply," says Secretary of Agriculture Tom Vilsack.
The report also found that the metal copper has made its way into American beef.
Often a waste product from industry, it can seep into the water that's fed to cattle.
In one incident in 2008, Mexican officials refused a shipment of U.S. beef because it contained more copper than Mexico allows.
America has no such restriction.
Copper can be dangerous if consumed in food over the long term. It is known to cause jaundice and kidney failure and can even be fatal.
"The Mexicans refused the meat that was going into their country yet there was nothing that could be done to prevent American consumers from being exposed to that," says David Acheson, former managing director for FDA Food and Import Safety. "That certainly is totally unacceptable in my book!"