News Analysis: Engine Oil Contamination Leading to Food Toxic — How to Choose Food-Grade Lubricants to Avoid Accidents?
Food Safety Series Report
2025
News Case Study: 57 Students in China Shandong Poisoned Due to Engine Oil Leak from School Cafeteria Steamed Bun Machine
In 2014, at the elementary section of Shouguang City Jitai Town No. 2 Middle School in China Shandong Province, 57 students suffered poisoning after eating in the school cafeteria, with six students failing to recover and being sent to Beijing for treatment. According to Mr. Zhao, a parent, the six students had similar symptoms—intermittent headaches, abdominal pain, and blurred vision. Five of them were hospitalized at the 307 Hospital for many days without significant improvement. “The doctors said there was no clear cause and therefore no targeted treatment,” Zhao said. On the morning of November 5, five students were discharged, and four of them were transferred to Beijing Tiantan Hospital for further treatment. “During the treatment in Beijing, two students were sent home,” Zhao added.
Yesterday afternoon at Tiantan Hospital, representatives from the Shouguang Food and Drug Administration, the Education Bureau, and the school handed a test report to the parents. The report stated that on September 12 at noon, 1,761 students had lunch at the school cafeteria. The menu included winter melon soup, small salted fish, and steamed buns.
At around 3:30 p.m., four students began to show symptoms such as nausea, vomiting, headache, and abdominal pain, with doctors initially diagnosing acute gastritis. The school then conducted an open inquiry with students, and a total of 57 reported feeling unwell. According to the report, the specific cause of the food poisoning was a sudden mechanical failure of the school’s steamed bun machine, which resulted in an engine oil leak (gearbox leakage, later sealed by the public security bureau). Some students who ate steamed buns contaminated with mineral oil experienced vomiting and gastrointestinal discomfort. The report, dated November 3, bore the official seal of the Shouguang Food and Drug Administration.
Since the test results of the vomit samples and retained food samples did not show virus levels exceeding standards, Mr. Zhao questioned the accuracy of the report. “The doctors said that with current technology, it is difficult to detect exactly which component of the engine oil caused the poisoning. Therefore, the vomit sample tests at that time were an important basis,” Zhao explained. A doctor at Tiantan Hospital’s outpatient department told the parents that one student’s imaging report showed the patient had demyelinating disease, requiring further tests to determine whether treatment was necessary. “Demyelinating disease can damage the central nervous system and is prone to recurrence,” the doctor noted, adding that there are many possible causes, one of which could be food poisoning.
Why Do Food Safety Incidents Keep Happening?
Food safety incidents often stem from more than a single oversight—they are the result of intertwined issues involving systems, culture, cost considerations, and execution. The four key reasons why food safety accidents occur repeatedly are as follows:
1️⃣ Cost-Driven Decisions Overriding Safety Considerations
Under operational pressure, many companies opt for non-food-grade raw materials or industrial-grade equipment lubricants to cut production or maintenance costs. In some cases, they delay equipment cleaning and maintenance, creating potential contamination sources.
2️⃣ Management Systems That Exist Only on Paper
Although food safety standards such as HACCP or ISO 22000 exist, some factories maintain compliant documentation while losing control of on-site operations. SOPs are not truly enforced, especially in non-food areas such as lubricants and cleaning agents, which are often neglected.
3️⃣ Insufficient Training and Awareness
Frontline operators may lack awareness of what “food-grade” means, under what circumstances contamination can occur, or that food-grade lubricants may have different performance characteristics. As a result, they may follow past habits, wrongly using industrial greases, causing cross-contamination, or performing improper repairs.
4️⃣ Weak External Oversight and Accountability Mechanisms
Some food factories lack regular third-party audits, or audits are conducted superficially. When incidents occur, accountability is unclear and corrective measures are incomplete, leading to repeated mistakes of the same kind.
If Food Poisoning Occurs, the Most Severe Consequences Could Be…
In 2017, according to a report from Hong Kong Wen Wei Po (Reporter: He Dehua), since the 12th of that month, multiple elementary schools in Xiamen reported cases of student food poisoning that resulted in class suspensions. According to parents from the affected schools and officials from Xiamen’s health department, at least three elementary schools experienced a suspected Salmonella outbreak, with more than 100 students affected. Preliminary investigations revealed that the poisoning occurred after the students consumed bread supplied by Sheng Fuxing Company during school hours. Sheng Fuxing, a Taiwan-invested company, immediately shut down all 70 of its stores in Xiamen for inspection after the incident. The company stressed that it had stopped supplying the implicated product to schools and recalled all remaining products for testing and investigation.
For food manufacturers, food safety is not just a regulatory requirement—it is an essential foundation for long-term business sustainability.
What Can We Do to Prevent Food Safety Concerns?
- Strictly Use Certified Food-Grade Materials and Lubricants
Ensure that all mechanical components that may come into contact with food (such as mixing, filling, packaging, and sealing parts) use only NSF H1 or 3H certified lubricants, and strictly prohibit the use of industrial-grade oils. All chemicals (including cleaners, disinfectants, and greases) must have Safety Data Sheets (SDS), clear labeling, and designated storage areas. - Establish Clear Internal Management Systems and SOPs
Integrate lubrication management into the HACCP or ISO 22000 framework, set up dedicated lubrication areas and records, and standardize all procedures related to machine maintenance (lubrication, repair, cleaning) so they are traceable and subject to review. - Conduct Regular Training and Cross-Audits
Implement cross-audit systems where QA staff or third parties inspect operations monthly to prevent procedural gaps. Provide regular training for on-site staff and maintenance technicians on food safety and proper lubricant use.
For over 30 years, Hou Cheng Trading has provided lubrication training and awareness programs for numerous leading Taiwanese food manufacturers. If you are interested in organizing such training, feel free to contact us.
Hou Cheng Trading Co., Ltd.
Founded in 1971 and headquartered in Taoyuan, Taiwan, Hou Cheng is dedicated to promoting the concept of specialty lubricants and introducing leading international lubricant brands to Taiwan and the Asia-Pacific region. Our food-grade products comply with NSF food-grade certification and Halal certification, and we provide the “Five Certificates” for food-grade safety assurance. Our solutions help extend the service life of your equipment while reducing operating costs. The full product line covers lubrication points across various applications, including pharmaceuticals, food, baking, beverages, and capsules. If you have lubrication needs not mentioned above, such as specialized lubrication products, feel free to contact our engineers for consultation.
Our Represented Brands:
- Brugarolas Specialty Lubricants (Spain)
- IKV Tribologie Specialty Lubricants (France)
- Anderol Specialty Lubricants (Netherlands)
- 77 Premium Automotive Oils (Netherlands)
- PM Automotive Care Products (Netherlands)
- OK Automotive Oils (Netherlands)
- UIKS Automotive Care Products (Japan)
- Dr. Oil Automatic Lubrication Systems
Fill out the form carefully—company, department, lubrication point(s), operating temperature, lubrication environment, etc.—and provide clear details. Our engineers will contact you promptly upon receipt.
