TAIPEI (Taiwan News) — Traces of a deadly toxin have been detected on the hands of the cook at a Taipei restaurant where at least 31 people have fallen ill. 

The Taipei government on Tuesday (April 2) announced that traces of bongkrek acid were found on the hands of a substitute Vietnamese cook surnamed Ho (胡), reported TVBS. Toxicology expert Yang Chen-chang (楊振昌) said it is likely that the food ingredients were contaminated, leading to contamination of the hands of the staff, knives, and cutting boards. 

Taipei Mayor Chiang Wan-an (蔣萬安) said that samples collected from the Malaysian restaurant chain Polam Kopitiam included environmental evidence, biomarkers, two knives, one cutting board, and biological traces from Ho's hands. Chiang said that on Monday evening (April 1), National Taiwan University Department of Forensic Medicine confirmed the presence of bongkrek acid, including on the cook's hands. 

The Ministry of Health and Welfare examined 35 food samples from the restaurant, including rice noodles, pandan leaves, rice flour, and soy sauce. Currently, none have tested positive for bongkrek acid. 

Yang said this is because the samples that tested positive were from March 24, while the food samples were collected on March 26. Therefore, it is likely the ingredients had already been disposed of or consumed, Yang said. 

This confirms “Polam Kopitiam indeed has a contamination source,” said Yang. He said people are currently concerned that the food samples that tested negative may not be from the same batch consumed by the patients. 

If samples taken from the chef or the hands of other staff test positive for bongkrek acid, it can probably confirm the presence of a contamination source, Yang said.