A student of Changchun University receives treatment at the provincial Qianwei Hospital in Changchun, capital of northeast China's Jilin Province May 19, 2004. More than 140 students were poisoned after breakfast Wednesday, and doctors blamed nitrite for the poisoning. The cause of the mass food poisoning is under investigation.

A student of Changchun University receives treatment at the provincial Qianwei Hospital in Changchun, capital of northeast China's Jilin Province May 19, 2004. More than 140 students were poisoned after breakfast Wednesday, and doctors blamed nitrite for the poisoning. The cause of the mass food poisoning is under investigation.

A sickened student of Changchun University receives treatment at the provincial Qianwei Hospital in Changchun, capital of northeast China's Jilin Province May 19, 2004. More than 140 students were poisoned after breakfast Wednesday, and doctors blamed nitrite for the poisoning. The cause of the mass food poisoning is under investigation.

Sickened students of Changchun University receive emergency treatment at the hospital attached to the university in Changchun, capital of northeast China's Jilin Province May 19, 2004. More than 140 students were poisoned after breakfast Wednesday, and doctors blamed nitrite for the poisoning. The cause of the mass food poisoning is under investigation.

Sickened students (background) of Changchun University receive emergency treatment at the hospital attached to the university in Changchun, capital of northeast China's Jilin Province May 19, 2004. More than 140 students were poisoned after breakfast Wednesday, and doctors blamed nitrite for the poisoning. The cause of the mass food poisoning is under investigation.