Melamine is a cheap way to fake high protein levels in wheat gluten.
The Chinese government moving to protect its multi-billion dollar exports of fruits and vegetables has now banned melamine and shuttered plants that may have used it.
China insists every container with agricultural products is inspected. But the reality, experts tell CBS News, is that serious spot checks are rare.
So buyers and even the government come to perhaps the most sophisticated private lab in the country for checking foods especially for pesticides, the number one problem, CBS News correspondent Barry Petersen reports.
At the lab they believe the foreign companies buying the goods have more leverage than the government.
"If I'm a supplier in China, I'm going to react much more if my customer tells me I need to improve what I'm doing and they want to make sure I'm doing a safe job," said John Chapple, general manager of Sino Analytica.
Most farms are tiny a third of an acre selling to a world where every country has different regulations like how much and what kind of pesticide can be used.
It's not just what Chinese farmers are putting on their crops, it's also what this country's industry is spewing into the air and dumping into the water that's threatening China's food safety.
Ten percent of China's arable land is now badly polluted. Cities let chemicals run in the streets and clog up the rivers.
"What's in these rivers is industrial," said China expert Orville Schell. "And that's what they use to irrigate crops."
China wants to be food exporter to the world an ambition that may falter if it cannot convince the world its products are as safe as they are cheap.