Dry Ice is now the latest weapon against rat infestation problem we have across New England. Killing these pesky rodents through suffocation of gaseous carbon dioxide shows impressive effectiveness than other traditional extermination method. Apart from that, it is safe to use as it pose no risk to other wildlife.
This rat extermination technique is done by filling rat burrows with dry ice pellets. As dry ice evaporates it kills the rats inside their nest. The treatment works within minutes but there are instances when some rats escape. Thus, an area must be treated a couple of times. But this treatment still looks more viable than using poison as far as safety is concern.
Also, the idea of trapping and suffocating rats in their own nest underground is a clever move since there's no need of removing dead rat bodies as it decomposes and eventually become part of the soil.