More than 5,000 ducks believed to have eaten feed containing a harmful red dye were slaughtered on Tuesday in north China's Hebei Province.

Over 300 kilograms of duck eggs were also destroyed and buried after the owners of five duck farms in Pingshan County admitted feeding the ducks with the red dye, which has tested positive for carcinogens.

The farm owners had heard that the dye would turn the yolk of the duck eggs red. Red-yolk duck eggs are commonly thought to be more nutritious than those with yellow-yolks and usually more expensive.

The farmers claimed that a trader named Zhu Laiyong from Baoding of Hebei had told them he could sell them a "red drug" that acted as a high-tech additive to make the ducks produce more red-yolk eggs. They each paid 25 yuan (about US$3) for a half-kilogram bag that was supposed to last for six months.

They also claimed that Zhu had bought the red-yolk eggs from them at 0.2 to 0.3 yuan higher per kilogram than normal eggs. 

At a press conference held yesterday the Hebei provincial government said two duck farms in Jingxing County were also found to have used the feed containing the dye. Two hundred kilograms of duck eggs and 70 kilograms of salted duck eggs were confiscated at the two farms.

The alleged contamination was first disclosed by a weekly news program on CCTV. In response the Beijing authorities immediately banned the sale of red-yolk duck eggs from Hebei and advised buyers to return the products.

Hebei has also imposed a ban on the sale of all red-yolk duck eggs in the province. "Three managers of three egg processing factories in Hebei have been arrested for their involvement in the dye contamination," said a spokesman for the provincial government on Tuesday.

The Beijing Food Safety Office on Tuesday confirmed that samples of red-yolk salted duck eggs sold in the city had been found to contain the carcinogenic red dye Sudan B. 

Beijing officials have so far seized 1,159 kilograms of the red-yolk eggs. Sales of all red-yolk duck eggs have been banned in Chengdu, capital of Sichuan Province and Guangzhou, capital of Guangdong Province.

(China Daily November 16, 2006)