Elephant Elephant at Columbus Zoo Photo: Shell Kinney[CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

The Association of Zoos and Aquariums will require all zoos to use barriers between humans and elephants by 2017, following the killing of an elephant caretaker by one of the two elephants in his care. The decision came after the Occupational Safety and Health Administration (OSHA) sent a team to investigate the man’s death. The death was ruled an accident, but it shed light on the dangers of close-quarter interactions between elephants and humans.

"There were simply too many accidents. The Association of Zoos and Aquariums board wanted to take steps to prevent this from happening again," spokesman Rob Vernon told the New York Times.

An estimated 500 people a year are killed by elephants, according to National Geographic. Most deaths are accidents and a result of elephants being squeezed into smaller spaces. The constriction of elephant habitats happens in zoos frequently; it also happens in the wild. As farmers expand their lands to make ends meet, the territory where elephants can safely roam has shrunk drastically. In Kenya, between 50 to 120 elephants are shot a year, according to World Wildlife Foundation estimates.

Neither a zookeeper nor a farmer, retired veterinarian James Laurita, 56, was killed earlier this month when he entered the elephant enclosure at Hope Elephants, the Maine-based organization he co-founded to care for retired circus elephants. Tending to the elephants in their enclosure was part of his daily routine, according to USA Today.

"The elephant was not aggressive in any way. It was clearly an accident," said Mark Belserene, administrator for the state medical examiner's office, immediately after Laurita’s death.

Last year a zookeeper was killed by one of his animals at Dickerson Park Zoo in Missouri. He too was crushed to death by the elephant in its enclosure. He had worked at the zoo for 30 years.