Samples of dried bamboo fungus from a supplier in Wan Chai and a poon choi manufacturer failed to meet hygiene standards in a test by the Centre for Food Safety in the run-up to the Lunar New Year. The centre conducted chemical and virus tests on 184 food samples from local markets, including cakes, dried seafood and nuts, and all were satisfactory except the dried bamboo fungus and the poon choi. The dried bamboo fungus was discovered to contain 0.17 parts per million of chromium, higher than the official standard of less than 0.1 parts per million. The product was believed to have been produced on the mainland and sold through a Hong Kong distributor. The poon choi dish, made by a manufacturer in Sheung Shui, was found to contain two types of disease-causing viruses far above accepted standards, which could lead to vomiting and abdominal pain. The poon choi manufacturer supplied dishes to local restaurants. Tina Mok, the centre's principal medical officer, said the dried bamboo fungus had been suspended from sale and the centre was investigating its source. The centre also issued a warning letter to the poon choi maker, urging it to take measures to ensure hygiene standards were met. Dr Mok said the centre had inspected the poon choi factory. 'Although the hygiene conditions are okay, we suspect that the materials have been polluted during the cooking procedures,' she said. The centre had offered some guidance to the manufacturer on how to keep the food fresh and hygienic. 'So far, we haven't had any complaints from consumers who fell ill because of their dishes,' she said. Poon choi, a traditional Chinese dish, usually contains numerous layers of ingredients such as meat, seafood, dried food and vegetables, some of which are perishable and unsuitable for long-term storage. In February last year, 441 people fell ill after eating poon choi dishes supplied by an eatery in Yuen Long. Dr Mok said the safety risk for poon choi was higher than other dishes as it was complicated to prepare. She reminded poon choi providers to plan preparation schedules carefully and stick to guidance on food storage to ensure the quality of the dishes.