Scientists have long worried about the ecological dangers of releasing powerful nano-antibacterials into waste and water streams. Now New Scientist reports that exposure to nano-silver, commonly used in odour-killing socks and clothing, triggers microbes to release four times the normal levels of nitrous oxide.  Nitrous oxide is a potent greenhouse gas. The UNFCC estimates that nitrous oxide has 280 times the global warming potential of carbon dioxide on a 20 year basis.