There is more than a little irony that it took a lot of dogs and cats being sickened by tainted pet food to focus attention on gaping holes in the nation's food safety system — and the role played by China, where safety regs often take a back seat to flooding cheap products into the U.S. market.

Turns out the poisonous pet food, which will cost U.S. companies millions in product recalls and lawsuits, was purposely adulterated with melamine waste, a practice apparently commonplace in China as suppliers try to boost profits any way they can.

The Chinese companies involved, to no one's surprise, professed innocence. “I never heard of such a thing,” an official of one accused firm said.

But a representative of a Chinese firm selling the chemical was quoted in the New York Times: “Many companies buy melamine scrap to make animal feed, such as fish feed. … No law or regulation says don't do it, so everyone's doing it.” The same article quoted a Chinese animal feed seller: “Melamine (costs) about $1.20 for each protein count per ton, whereas real protein costs about $6.”

It's anybody's guess how pervasive the contamination problem is. On the heels of the pet food scandal came reports of 2.5 million broilers at an Indiana poultry farm being fed melamine-laced rations.

Agriculture officials in Mississippi, Georgia, and other states recently put stop-sale orders on catfish imported from China after positive tests for a banned antibiotic.

These and other incidents, including a nationwide recall by Wal-Mart of thousands of baby bibs from China that contained high levels of lead, have pointed out not only the problems that can come from virtually unfettered trade with countries whose regulatory standards are much lower than ours, but also the glaring shortcomings in the U.S. system and agencies for monitoring and inspecting imports of critical food, drug, and other items that could have adverse health or safety consequences.

Congressional hearings following the pet food contamination turned a not-too-favorable spotlight on the USDA and Food and Drug Administration for their inability to provide tighter inspections of imported foods and other products going into the U.S. manufacturing and retail systems.

Noting that the FDA is greatly understaffed and underfunded in terms of coping with the imports flood, there were also calls for an urgent reorganization of a system that's spread across more than a dozen agencies, as well as charges of politicization, intimidation and censorship of FDA scientists, and scientific fraud within the agency.

Beyond that, in a sharply-worded statement, Larry Mitchell, CEO of the American Corn Growers Association, charged that Wal-Mart, as the world's largest company and a major buyer of Chinese goods, has significantly contributed to the problem. It has, he said, “quietly, but forcefully, opposed additional food safety regulations, port inspections, and country-of-origin labeling … and has put corporate profits over its customers' safety time and again.”

Because Wal-Mart is “uniquely positioned to restore confidence in our food supply” and bring about “lasting changes,” Mitchell said, “maybe it will (begin fulfilling) its obligation … to help (China) move toward a meaningful solution.”