Between 1946 and 1958, the US government tested 67 nuclear weapons in the Marshall Islands. It later dumped radioactive waste from the tests into a crater on one of the islands, placing an 18-inch-thick concrete dome over the horrifying sludge.

Because the crater was only supposed to be a temporary storage solution, the bottom of it was unlined. That's led to recent concerns that the "coffin" is leaking radioactive waste into the Pacific Ocean — a potentially devastating blow to both the environment and the people of the region.

While speaking to students in Fiji on Thursday, United Nations Secretary General Antonio Guterres said that Marshall Islands President Hilda Heine was "very worried" about the possibility of radioactive waste leaking from the coffin.

While he didn't offer any specific solutions for dealing with the waste-filled crater, he did say that "a lot needs to be done in relation to the explosions that took place in French Polynesia and the Marshall Islands," according to the AFP, adding that "this is in relation to the health consequences, the impact on communities and other aspects."

This article was originally published by Futurism. Read the original article.