Editor’s Note: Sign up for CNN’s Meanwhile in China newsletter, which explores what you need to know about the country’s rise and how it impacts the world. Hong Kong CNN  —  Public outrage is mounting in China over allegations that a major state-owned food company has been cutting costs by using the same tankers to carry fuel and cooking oil – without cleaning them in between. The scandal, which implicates China’s largest grain storage and transport company Sinograin, and private conglomerate Hopefull Grain and Oil Group, has raised concerns of food contamination in a country rocked in recent decades by a string of food and drug safety scares – and evoked harsh criticism from Chinese state media. It was an “open secret” in the transport industry that the tankers were doing double duty, according to a report in the state-linked outlet Beijing News last week, which alleged that trucks carrying certain fuel or chemical liquids were also used to transport edible liquids such as cooking oil, syrup and soybean oil, without proper cleaning procedures. On Tuesday, the food safety office of China’s administrative State Council announced an interdepartmental team would investigate the transportation of edible oil, pledging that those responsible for any malpractice “will be severely punished in accordance with the law,” according to a statement posted on the website of the top market regulator. The two companies named in the media report have also said investigations are underway. Meanwhile, other major edible oil manufacturers not named in the report issued statements saying they did not use fuel trucks to transport their products. Food security and safety have been cornerstone issues for Chinese leader Xi Jinping, who has linked them to national stability and called their successful oversight a test of a government’s ability to govern. A chef prepares a Sashimi platter at FUMI Japanese restaurant in Hong Kong on August 24. Noemi Cassanelli/CNN Related article China says its ban on Japanese seafood is about safety. Is it really? As discussion of the claims exploded across social media in recent days, China’s tightly controlled national-level state media also rushed to criticize alleged malpractice – in a sign the state wanted to be seen driving condemnation of the issue, as opposed to acting to tamp down public anger. State broadcaster CCTV earlier this week called the alleged practice and the potential contamination of food products from left-behind fuel in the tankers “tantamount to poisoning” and showing “extreme disregard for consumers’ lives and health.” Communist Party mouthpiece the People’s Daily said when food safety is at stake there is “no right to silence” and called on regulators to act. Experts quoted in official media also discussed health hazards of the alleged practices. “Using chemical tankers for edible oils will inevitably result in residual contamination,” said Liu Shaowei, a food safety expert cited by CCTV. Long-term consumption of the oils with chemical residues can lead to poisoning with symptoms like nausea, vomiting, and diarrhea. It may even cause irreversible damage to organs including the liver and kidneys, Liu added, according to the broadcaster. Public backlash and investigations On China’s heavily moderated social media platforms, many members of the public called for product recalls and greater industry oversight. Some also appeared to link the situation to broader issues in the country, where an economic downturn is driving social frustration and there are deep-seated concerns about the limits of accountability for powerful and government-linked entities. “Even the cooking oil essential to people’s daily lives has now become problematic… Ordinary people cannot be properly safeguarded… Now I just want to scoff at (phrases like) ‘rule of law’ and ‘serving the people’ whenever I see them,” read one comment on China’s X-like social media platform Weibo, that garnered thousands of likes. As public anger simmered, state-owned Sinograin on Saturday said it had launched inspections across its operations and pledged to stop working with any transport providers found to be in violation of safety regulations. “Sinograin requires all units in the system to strictly fulfill their responsibilities, abide by work standards and prevent contamination risks to grain and oil reserves,” the company, China’s official grain stockpiler, said in a statement posted on its official Weibo account. This photo taken on June 27, 2024 shows employees working on sun protection clothing at a factory in Fuyang, in eastern China's Anhui province. (Photo by AFP) / China OUT Stringer/AFP/Getty Images Related article There is no end in sight for China’s uneven economic recovery A staff member from Hopefull Grain and Oil Group on Monday told state-owned news outlet Economic View that “relevant departments” have investigated the matter and would make an official announcement. The person added that a tanker described in the media report was not owned by the company and said there were no quality issues with their brand’s oil products, according to the Economic View. CNN was not able to reach Hopefull Grain and Oil Group despite repeated calls. When reached by phone by CNN, a representative from Sinograin declined to provide additional comment past its online statement. There has been no official announcement of product recalls. However, CNN found no products were available to buy on the official store of Sinograin’s Jinding cooking oil brand on e-commerce platform Taobao on Wednesday afternoon, though it was unclear why. Experts cited by state media noted that while China has no specific law governing the transport procedures of edible oils, national guidelines say transporters should use “dedicated containers, and non-edible vegetable oil tank trucks and containers are strictly prohibited for this purpose.” Meanwhile, China’s Food Safety Law requires that food “must not be stored or transported together with toxic or harmful items” and mixing toxic and harmful non-edible raw materials is a criminal offense punishable by a potentially lengthy prison sentence. Those found guilty of food poisoning resulting in a fatality can face the death penalty. Food safety ‘a major test’ Despite rising living standards in recent decades, food safety has been an ongoing issue in China, where dozens of high-profile scandals have been reported by local media since the early 2000s, sparking tighter government regulation. In one of the most egregious examples, six infants died and some 300,000 others were sickened by milk powder formula containing the toxic industrial chemical melamine. Several executives found to be responsible for the 2008 case were ultimately handed death sentences, and the tragedy drove deep mistrust of domestic products and food safety in China. The widespread sale and use of “gutter oil” – or cooking oil recycled from the gutter, household drains and grease traps – emerged as a major issue in the early 2010s. Another case in 2022, also exposed by state media, showed how “dirty” pickled cabbage was supplied to popular instant noodle brands. A cat on an ancient street in China. Zhang Peng/LightRocket/Getty Images/File Related article 1,000 cats rescued in China from being slaughtered and sold as pork, mutton Xi has repeatedly stressed the importance of food safety and the security of grain and food staple supplies. In a 2013 speech cited in a People’s Daily report last year, Xi said the ruling Communist Party’s ability to “provide satisfactory assurances on food safety” is a “major test of our governance capabilities.” “As the ruling party in China, if we cannot manage something as fundamental as food safety, and if we cannot address the issue and even allow it to persist without proper resolution over a long period, the party’s ability to govern will be challenged,” Xi said. Yanzhong Huang, a senior fellow for global health at the Council on Foreign Relations in New York, said the directive to investigate the current scandal likely came “from the very top” – noting that food safety is both a key issue linked to government legitimacy and the allegations are landing at a sensitive time when economic hardship in China is causing a more “volatile society.” The situation, Huang added, had the potential to be the largest food safety scandal since 2008, given the volume of oil regularly transported and the implication that this may have been a longstanding issue that could have affected swaths of the population. “This problem is even worse (than some past scandals) because you can avoid eating gutter oil, for example, by not dining out, but you cannot avoid the contaminated cooking oil, because it’s difficult to identify and to avoid in everyday meals,” he said. “That’s why people have become so upset.” CNN’s Laura He contributed to this report.