More than 30 students of Qicheng Middle School in Fengqiu county, Henan province, showed symptoms of vomiting and diarrhea after eating the school lunch supplied by a catering company on Tuesday last week.

The students complained that the food had already deteriorated before it was served.

After the students were rushed to hospital, the headmaster of the school told the media in a tearful voice that he was unable to change the catering company, although the parents and students had complained about the food before, because the company was supplying the lunches as the winner of a department of education tender.

Food safety is a big deal, and school lunches directly concern the health of students.

Preliminary test results of the food showed that some samples contained high levels of Escherichia coli (E. coli) bacteria which can cause diarrhea and vomiting, and other symptoms of food poisoning.

As of Saturday, at least four officials in the education bureau, market regulation bureau and food safety department of the county had been put under investigation, according to the county authorities.

Meanwhile, a probe is being carried out targeting the catering company and the bidding process.

The catering company is part of a commerce and trade group registered in Beijing that runs a variety of businesses.

The company started providing food for the middle school on Nov 15, eight days before the incident happened. Students and their parents had repeatedly complained to the school about the quality of the food since then.

Although the tender process was in accordance with the regulations and the bid was compliant, the higher-level authorities should look into the incident rather than the county itself.

Open bidding was introduced years ago to regulate government departments' procurement of services and materials. But slack supervision over the procurement process can easily make it a cover for underhand dealings.

- PEOPLE'S DAILY