Police in north China have arrested seven people suspected of producing powdered milk tainted with the same industrial chemical that killed at least six babies in 2008.State press today said Wang Zhigang, an official at the Jinfulai dairy company in Shanxi province, was among those arrested for allegedly putting excessive amounts of melamine in the milk powder. At least six babies died and 300,000 others were taken ill by contaminated milk products in a scandal that rocked the country's dairy industry in 2008 and led to worldwide recalls of Chinese dairy products.Two people were executed for their role. Last week, China again pledged to punish people guilty of food safety crimes, calling for the death penalty to be applied in cases where culprits deserve it.