The use of “cyanide bombs” to kill wild animals has been authorised by the Trump administration.
The US Environmental Protection Agency (EPA) has taken the first step to re-authorise the spring-loaded traps, known as M-44s, which are filled with sodium cyanide.
The devices are embedded in the ground and spray the poison when activated by animals attracted to bait, such as coyotes and foxes.
Idaho decided against using the traps after a 14-year-old boy was injured and his dog died when he came across one on land near his home in 2017.
Environmental groups have criticised the decision to reintroduce the devices, which they deem to be unsafe.
Collette Adkins, carnivore conservation director at the Centre for Biological Diversity, said cyanide traps “can’t be used safely by anyone, anywhere”.
She added: “While the EPA added some restrictions, these deadly devices have caused too much harm to remain in use.
“We need a permanent nationwide ban to protect people, pets and imperilled wildlife from this poison.”
In 2018, the traps 6,579 animals, mostly coyotes and foxes, compared to 13,232 animals in 2017.
The Centre for Biological Diversity said a child was temporarily blinded and three family dogs were killed in two incidents in Idaho and Wyoming in 2017.
A wolf was also accidentally killed by an M-44 set off in Oregon that same year, the organisation claimed.
The traps have so far been banned in Oregon, Colorado and Idaho after safety concerns were raised.