1 Causes 1.1 Coal ash 1.2 Sewage 1.3 Pesticides and herbicides 1.4 Agents of war 2 Health effects 3 Ecosystem effects 4 Cleanup options 5 By country 5.1 People's Republic of China 5.2 United Kingdom 5.3 Canada 5.4 India 6 See also 7 References 8 External links