Wan said Shuanghui has adopted six measures to prevent such contamination from recurring and said the company has been made into a "scapegoat". He also said the incident has cost Shuanghui more than 12.1 billion yuan ($1.85 billion), according to the latest calculations.

The tainted pork, whose harmful effects have been described as "isolated" by the Ministry of Agriculture, has added to the country's long list of food scandals.

Following the scandal, the Ministry of Agriculture announced the results of a spot-check that tested more than 310,000 pigs in Henan province, saying that only 134 of the animals were found to have been fed with the illegal additive.

Even so, pigs in Jiangsu and Guangdong provinces and Shanghai yielded positive test results, suggesting the tainted pigs have been sold outside of Henan province.

Yang Guizhi, a 53-year-old Henan resident, said she is very worried and that she stopped buying meat when she heard of the scandal.

"I feel scared when I look back and realize I always bought lean pork," she said. "I may eat beef or lamb in the future, but no more pork."

Yang said she has told her daughter - who works in Beijing - to eat less meat.

Sang Liwei, a food safety lawyer in Beijing and a representative of the Global Food Safety Forum, a non-government organization, told China Daily that "third-party tests", conducted by an agency independent of both food producers and the government, may be the best way to respond to the concerns that have arisen over food safety during a series of recent scandals, starting with an infamous discovery of tainted milk in 2008.

"The results will be disappointing if we let companies check the quality of their own food products," he said. "So our organization has been promoting the idea of third-party tests for a long time, and I hope this tainted-pork case will make food processors aware of the importance of this idea."

The country's quality watchdog, the General Administration of Quality Supervision, Inspection and Quarantine and the China Association for Quality, said it is adopting a system to assess the efficiency of the quality supervision measures undertaken by local governments.