CNA Explains: Why was the ByteDance mass food poisoning case so severe, and how does it compare to previous incidents?

SINGAPORE: Investigations are underway after a mass food poisoning incident at the Singapore office of TikTok owner ByteDance on Tuesday (Jul 30).

A total of 130 people reported having gastroenteritis symptoms, the Ministry of Health (MOH) and Singapore Food Agency (SFA) said on Wednesday. 

In response, the health authorities have suspended the food business operations of Yun Hai Yao at Northpoint City and Pu Tien Services at Senoko South Road. Both caterers had supplied the food that was consumed by ByteDance employees, they added.

The Singapore Civil Defence Force (SCDF) deployed 17 ambulances to the scene in response to the incident.

ByteDance employees recounted seeing vomit on the floor and colleagues wincing in pain. A 28-year-old employee who declined to be named told CNA that the "whole office smelled like vomit".

Fifty-seven people were taken to the hospital on Tuesday and 17 remain hospitalised but are in stable condition. 

The suspected cause? Food from a canteen on the 26th floor of One Raffles Quay, which the affected employees had consumed. 

What could have caused such severe bouts of food poisoning, and how can it be avoided? 

What causes food poisoning? 

According to Ms Chan Fong Ying, the senior food safety consultant and trainer at consultancy ISRC, severe food poisoning cases are often linked to “high-risk” foods and conditions that facilitate the growth and transmission of harmful pathogens.

“High-risk foods include undercooked meats, raw poultry, seafood, unpasteurized dairy products, and prepared salads like coleslaw and pasta salads,” said Ms Chan. 

She said that these foods can harbour bacteria such as salmonella, E. coli, listeria, and staphylococcus aureus, which produce toxins that can cause intense gastrointestinal symptoms.

In addition, improper food handling practices, such as inadequate cooking, poor refrigeration, and cross-contamination of raw and cooked food, can significantly increase the risk of contamination.

Food prepared by individuals with poor hygiene or those who are unwell can also introduce pathogens into the food supply. 

Likewise, conditions such as warm temperatures and prolonged storage at unsafe temperatures can promote bacterial growth in food, and contribute to the severity of the illness, she added. 

Why was the food poisoning case at ByteDance so severe? 

A ByteDance employee told CNA that his colleagues felt nauseous about an hour after lunch, with many people vomiting and having diarrhoea. Some staff were even lying on the floor, he added. 

Ms Chan said that the acute symptoms observed in the ByteDance food poisoning case, where individuals experienced immediate vomiting, suggest exposure to a “highly potent toxin or pathogen”. 

“Such rapid onset of symptoms is not uncommon in food poisoning cases, especially when the contamination involves toxins produced by bacteria like staphylococcus aureus or bacillus cereus,” she said.

She explained that these bacteria can produce toxins that cause “intense gastrointestinal distress” within a few hours of ingestion.

Other factors that can contribute to the severity of symptoms can include the amount of contaminated food consumed, as well as the type and concentration of the toxin or pathogen, she added. 

CNA also understands that ByteDance engages licensed external vendors to cater food for its offices, and that food is not prepared or cooked at its office premises in Singapore.

Ms Chan said that catered food can present  “unique food safety challenges” since it is often prepared off-site, transported, and then served at a different location.

“These challenges include maintaining proper temperature control during transportation to prevent bacterial growth, ensuring that food is cooked to the right temperature, and preventing cross-contamination between raw and cooked foods,” she said. 

“The risk of foodborne illness can also increase if food is held for extended periods before serving.” 

She said that caterers should mitigate the risk of contamination by ensuring warm food is kept sufficiently warm at above 60 degrees Celsius, cold food is kept in insulated containers to maintain a temperature of between 0 to 4 degrees Celsius, and that all food handlers are trained with proper hygiene and food handling practices, among other measures. 

How to identify spoiled or contaminated food?

Ms Chan said that there are "telltale signs of spoilage" that consumers can identify. 

"Common indicators of spoiled food include changes in colour, texture, odour and with bloated packaging," she said. 

For instance, food that appears discoloured, slimy, has an unusual, sour, rancid smell or visible mould growth should be discarded, she added. 

Have there been similar cases in the past? 

There have been several high-profile cases of food poisoning here over the years, some which have resulted in deaths. 

In the worst case of food poisoning to date, more than 150 people fell ill from food poisoning after eating at an Indian rojak stall in 2009, causing Geylang Serai Market to be temporarily shut down. Thirty-seven people were hospitalised and two died as a result. 

In 2014, hygiene lapses caused the death of a four-year-old boy after he ate food from a nasi padang stall in Northpoint Shopping Centre's Kopitiam food court. An investigation by the National Environment Agency (NEA) found that one of the food handlers at the stall was unregistered, and that the stall's staff also failed to protect food in a covered receptacle.

In 2018, 47 people were hospitalised after dining at Spize restaurant, which resulted in one death. A coroner had found "alarming lapses" in food hygiene at the River Valley Road outlet.

Last week, more than 160 personnel at the SCDF academy fell ill with gastroenteritis, with investigations still ongoing for the mass food poisoning incident.

Other high-profile cases this year include reports of food poisoning for customers at Peach Garden's Thomson Plaza branch, as well as Edge buffet restaurant at Pan Pacific Hotel. 

Could this be serious enough to warrant tighter food safety regulations in Singapore? 

Ms Chan said that food poisoning can become “extraordinarily severe and potentially fatal” due to several factors.

Some pathogens in contaminated food can cause botulism, which produces toxins that can lead to paralysis and respiratory failure if untreated.

“Severe dehydration, resulting from persistent vomiting and diarrhoea, can cause kidney failure, shock, or even death, particularly in vulnerable populations such as infants, the elderly, and those with weakened immune systems,” she added. 

She said that cases of severe food poisoning can lead to stricter enforcement of food safety regulations in Singapore.

One example was the Spize restaurant incident in 2018, which led to the Singapore Food Agency (SFA) implementing hefty penalties for food hygiene offences. 

In the aftermath of the incident, Spize restaurant lost its River Valley Road outlet licence in December 2018. Spize and related company Spize Events were fined S$32,000 (US$23,900) in December 2020 over the incident.