BEIJING, Nov. 21 -- First it was eggs with red yolks, and now fish with thin, round bodies. It seems pretty things are not supposed to be put on our plates.

    Only a few days ago, ducks in some parts of Hebei Province were found to have been fed a special red dye, that later tested positive for carcinogens, so that their eggs would have red yolks. Compared with regular yellow-yolk eggs, these red-yolk eggs fetch a premium price in supermarkets and farmers' markets around the country.

    Over the weekend, turbot fish sold in Shanghai were found to contain an element that causes cancer. They have been traced to fisheries in Shandong Province. Further testing revealed that fodder for the fish contained chemicals usually used to treat sick animals.

    As one can expect, prices for turbot fish plummeted as authorities began inspections of other fisheries.

    But how can a grocery shopper be sure that the next food item they put into their basket is safe to eat?

    The harmful eggs and fish were uncovered by random checks by the authorities or the media. While they deserve plaudits for these efforts, it is obvious that such sporadic safety checks which are often clandestine, in the case of media investigations are not enough. There has to be a mechanism to make sure every food item sold is free from harm.

    Of course it is unrealistic to test every egg or every fish. But the testing has to be so systematic and foolproof that greedy growers would not even think of using noxious ingredients in their feed. It is too late when inspectors go into overdrive after learning of incidents of mass poisoning or consumer complaints.

    Theoretically we do have special departments dealing with food safety. But where were their eyes and ears when a reporter who visited a duck farm heard that farmers never eat their own poultry? Shouldn't that be a tip-off for a sign of dirty dealing?