A Hebei court sentenced a man on Monday who injected pesticide into dumplings, causing 13 people in Japan and China to become ill in January 2008, to life in prison.

Lyu Yueting, a former worker at the Tianyang Food Plant in Hebei province entered the factory’s refrigeration storage in 2007 five times to inject methamidophos, a pesticide, into the dumplings.

After failing to inject the pesticide twice during July and August 2007, the 39-year-old changed the syringe he used from a capacity of 5 ml to 10 ml and entered the refrigeration storage three more times from October to December 2007, according to the court.

Some of the poisoned dumplings were exported to Japan and some were sold in Chengde, Hebei province, China, poisoning 13 people. One of those who ate the dumplings became seriously ill, six experienced minor sickness and six became slightly unwell, according to the court.

Lyu started work at the factory in 1993 and was a temporary worker until 2007.

He poisoned the dumplings to gain attention from management and create an opportunity to request salary increase and welfare benefits, the court said.

"I was paid only 100 yuan for a Spring Festival bonus in 2007, while other contracted workers received thousands of yuan. I thought that I deserved higher pay as I had worked for the company for so long. I was hoping the management could pay attention to people like me," Lyu said at his trial on July 30.

Tianyang was forced to shut down and recall all its products, causing direct losses of at least 5.5 million yuan ($897,000) as of Jan 28, 2010.

Prosecutors said Lyu committed the crime several times with long-term planning and the case endangered food safety, jeopardizing the health of an unspecified number of people.

Lyu was arrested in 2010 after a two-year investigation by police.

More than 50 people, including embassy officials from Japan, attended the court and heard the verdict.

Contact the writer at houliqiang@chinadaily.com.cn