Melamine was apparently added to wheat gluten and rice protien by a company in China to make their product appear to be richer in content. It was then imported by an American company who in turn sold it to feed manufacturers for use in their product. It appears that it may have been originally imported in August of last year and the companies started using the product in September or October 2006. Presumably no one who examines imported goods, nor any of the companies involved were aware of the presence of the melamine, until cats started getting sick in December 2006 or January 2007(my assumption is that because they are the smallest of the animals involved they were the first to show signs of the contamination). It then took at least a month for everyone to figure out why so many pets were getting sick. During that time, more and more contaminated food was being manufactured and sold.