Melamine has once again become the focal point of a global food safety scare. The first reported incident happened in 2007 when pet food produced in China was found to have been contaminated with melamine. The second incident reported happened only a few weeks ago when melamine contaminated infant formula caused death and illness among Chinese infants. 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.

Powerful announcements came after food safety tests earlier this week found that eggs produced in three different provinces in China were contaminated with melamine, which is blamed for causing kidney stones and renal failure in infants. Four brands of eggs have since been found to be contaminated, and agriculture officials speculate that the cause was probably melamine-laced feed given to hens.

The tests have led to recalls of eggs and consumer warnings. The cases are fueling global concerns about Chinese food. In light of Thursday reports by state media on the widespread use of the chemical in animal feed, health experts say the government clearly knew melamine was being added for more than a year, since contaminated dog food made it to markets in North America, but didn't crack down on producers as promised.

The World Health Organisation's food safety chief, Jorgen Schlundt, last week called China's food-safety system "disjointed" and said poor communications between ministries and agencies may have prolonged the outbreak of melamine poisoning. "Coordinate and cooperate to investigate and punish major incidents," the official Xinhua news agency quoted Health Minister Chen Zhu as saying.