Beijing First it was baby milk formula. Then, dairy-based products from yogurt to chocolate.
Now chicken eggs have been contaminated with melamine, and an admission by state-run media that the industrial chemical is regularly added to animal feed in China fueled fears Friday that the problem could be more widespread, affecting fish, meat and who knows what else.
Peter Dingle, a toxicity expert at Murdoch University in Perth, Australia, said, however, that aside from the tainted baby formula that killed at least four Chinese infants and left 54,000 children hospitalized just over a month ago, it is unlikely humans will get sick from melamine.
The amount of the chemical in a few servings of bacon, for instance, would simply be too low, he said.
But Dingle and others said China should have cracked down sooner on feed companies that have boosted their earnings by fortifying their products with the chemical, which is normally used in the manufacture of plastic and fertilizers.
Rich in nitrogen, melamine gives low-quality food and feed artificially high protein readings.
"Traders can make a lot of profit by doing it," said Jason Yan, the U.S. Grains Council's technical director in Beijing.
Extremely high levels of melamine - as found in the Chinese baby formula - can cause kidney stones, and in extreme cases can bring on life-threatening kidney failure.
But while scientists say it's not dangerous to ingest small amounts, they cannot be definitive because there have been no tests on melamine's effects in humans. Until the contaminated baby formula became public in September, there was never any reason to.
That leaves consumers worldwide, particularly parents, worried about food products from China, and even those made elsewhere with ingredients imported from Chinese companies.
Among those not taking any chances is Pranee Suankaew, a homemaker in Bangkok, Thailand.
"Let's go, let's go," the 37-year-old mother said as she tugged her 4-year-old away from the candy aisle where he eagerly eyed a bag of M&Ms. "We're getting you fruit and a lollipop. There's no milk in that."
She said she usually gives in to avoid tantrums. "But this time, I told him, no, no, no."
Experts say melamine sometimes accidentally leaches into the food supply in low levels, from things like plastic dinnerware. It can also seep in from some pesticides and fertilizers.
But in China it's become clear that the chemical is deliberately added.