A labourer works at a salt production factory in Nangqian county, northwest China's Qinghai province July 24, 2007. A national production standard for food fillings has been formulated and is likely to be published by the end of this year, the China General Chamber of Commerce announced on Monday as public doubts linger over the cardboard bun saga, Xinhua News Agency reported. Picture taken July 24, 2007.