In 2007 New Scientist magazine reported that the cause of an outbreak of American cats and dogs dying of kidney problems had been discovered. ('Pet killer identified', New Scientist, 24 November 2007, p. 4) Two chemicals, melamine and cyuranic acid, had been added to wheat and rice gluten exported from China to the US for use in pet food manufacturing, to raise their nitrogen content.
One year later, in November 2008, Chinese authorities reported that since July that year 6 infants had died of of kidney damage, 54,000 had been hospitalised, and around 300,000 people had been adversely affected by melamine added to milk to raise its protein content. (Read a thorough and very well-referenced account of the scandal here >>) Proteins contain nitrogen, and too much nitrogen is bad for kidneys.
Something that kills cats and dogs will likely kill small children, yet nothing was done in China to improve food safety practices once the dead American pets were shown to be the canaries in the 'food mine', warning of the potential harm to humans ahead. Despite China executing two of those guilty of making melamine-laced 'protein powder' for adding to milk in 2009, in 2010 more melamine contaminated milk was found. ( China dairy products found tainted with melamine, 9 July 2010)
As horrible as it is that food is being deliberately contaminated in China (and elsewhere, as China does not have a monopoly on those putting personal profit before public health and safety) it is doubly sad in China's case. That's because increasing milk and other animal protein consumption to the levels common in the industrial, globally-sourced diet first developed in the UK and its colonies, and then expanded by the USA , has led to the Chinese population starting to suffer from the same levels of chronic non-communicable diet-related diseases, such as cardiovascular disease, and cancer, that lead to slow deaths. (See the China Health and Nutrition Survey.) Even more ironically, it puts them at the same risk of kidney problems. ('High protein diet brings risk of kidney stones' Scott Gottlieb, BMJ, Aug 24, 2002)
So while contaminating food with extra nitrogen is completely unethical given the harm it can cause, one ask to ask questions about how ethical it is to encourage and promote high animal protein diets in the first place, from the public heatlh point of view. (For all the other downsides, see the case made by Philip Lymbery in his recently published book Farmageddon.)