The food poisoning at two south China restaurants, which left two people dead and 63 others ill on Saturday, may have been deliberate, said a health official on Wednesday.
Police found no evidence of sodium nitrite, the substance that caused the poisoning, being stored in the two restaurants, nor did they find any in the seasonings, enabling them to rule out the possibility that kitchen staff mistook the chemical for salt or sugar, said Wei Houming, a spokesman of the public health bureau of Longgang District, in Shenzhen.
However, sodium nitrite was detected in the water collected from the restaurant drains and cloths used to cover food. The chemical was also found on top of the kitchen ranges.
Based on the evidence, police suspected some of the food served in the restaurants could have been contaminated by sodium nitrite in an "abnormal" way, Wei said.
The owners of the two restaurants have been under police investigation. Currently, officials from Shenzhen health authorities and disease control center were investigating the patients and the employees of the company as well as collecting evidence.
A 21-year-old man who came to work at Shenzhen-based BYD Company Ltd. from neighboring Guangxi Zhuang Autonomous Region in June 2006, and a woman of 18 who came from Guizhou Province last October had died from the poison, Wei said.
Representatives from the company had talked with the victims' families and promised compensation according to the law.
Sixty-three BYD workers suffered stomachaches, vomiting and other symptoms around 11:00 a.m. Saturday after having lunch at two small restaurants near their workplace in the Baolong Industrial Zone of Longgang District.
The two people died after treatment and 42 others left hospital on Sunday afternoon. Another 10 were released from hospital on Monday, according to the district health bureau.
The small restaurants and snack bars not up the hygiene standard in the neighborhood were once inspected and required to shut but the some were still in business since the local health department was understaffed, said Zhong Yongsheng, publicity head of the Longgang neighborhood committee.
"All the snack bars that were not fully registered in the neighborhood have been suspended so far," Zhong said. "Police carry out round-clock patrol in that area in case some owners resume operation."
"After the cause of the accident is made clear, we will clear up the unregistered restaurants thoroughly."
The BYD company has more than 10,000 workers but only two canteens which serve breakfast, lunch and supper within a limited time. For that reason, many people choose to dine out in small and cheat restaurants or snack bars and most of the restaurants were not registered and the hygiene conditions were not up to standard.
Zhong said they would set up a temporary canteen in the Baolong Industrial Zone to cater for the employees for the BYD company.
Sodium nitrite, similar in appearance to salt, is used as an industrial color fixative, but is also used in small amounts as a meat preservative.
Health experts warned that 0.2 grams of sodium nitrite could poison an adult and three grams were enough to kill.
Founded in 1995, BYD, listed in Hong Kong in 2002, is a private high-tech company. It announced itself at its website (www.byd.com.cn) the world's second largest rechargeable batteries and also a major domestic IT components and auto producers with more than 120,000 employees in China.