Some agricultural products sold at supermarkets including Carrefour, METRO and Auchan havefailed quality tests, Shanghai's food watchdog said on Wednesday.

A batch of Chinese chives sold at the Qibao outlet of Carrefour in Minhang District contained excessive cadmium, according to the Shanghai Administration for Market Regulation.

Long-term intake of cadmium can lead to kidney and bone damage, the administration warned.

A batch of bullfrog sold at the Songjiang branch of METRO failed for antibiotic AOZ, banned in food as it can lead to hemolytic anemia, polyneuritis, acute hepatic necrosis and eye harm.

Green vegetables sold at the Renmin outlet of Auchan in thePudong New Area failed on insecticide.

In total, 523 batches of food samples including bean products, agricultural products, fruits and vegetables were tested and six were found to be substandard.