patented in the us in 2013. these preparations rely on dehydration and electrolyte imbalance to cause death. inert gas killing of burrowing pest animals is another method with no impact on scavenging wildlife. one such method has been commercialized and sold under the brand name rat ice. non-target issues wildlife eating rodenticide from a bait station intended for rats secondary poisoning and risks to wildlife one of the potential problems when using rodenticides is that dead or weakened rodents may be eaten by other wildlife, either predators or scavengers. members of the public deploying rodenticides may not be aware of this or may not follow the product's instructions closely enough. there is evidence of secondary poisoning being caused by exposure to prey. the faster a rodenticide acts, the more critical this problem may be. for the fast-acting rodenticide bromethalin, for example, there is no diagnostic test or antidote. this has led environmental researchers to conclude that low strength, long duration rodenticides (generally first generation anticoagulants) are the best balance between maximum effect and minimum risk. proposed us legislation change secondary poisoning is caused by eating poisoned prey, showing how predators are effected not being the target within the environment. in 2008, after assessing human health and ecological effects, as well as benefits, the us environmental protection agency (epa) announced measures to reduce risks associated with ten rodenticides. new restrictions by sale and distribution restrictions, minimum package size requirements, use site restriction, and tamper resistant products would have taken effect in 2011. the regulations were delayed pending a legal challenge by manufacturer reckitt-benkiser. notable rat eradications the entire rat populations of several islands have been eradicated, most notably new zealand's campbell island, hawadax island, alaska (formerly known as rat island), macquarie island and canna, scotland (declared rat-free in 2008). according to the friends of south georgia island (www.fosgi.org), all of the rats have been eliminated from south georgia island (which is about the size of long island, new york). alberta, canada, through a combination of climate and control, is also believed to be rat-free.