And marine biologist Robert Richmond, from the University of Hawaii, told the BBC: "We've seen an inadequate radiological, ecological impact assessment that makes us very concerned that Japan would not only be unable to detect what's getting into the water, sediment and organisms, but if it does, there is no recourse to remove it... there's no way to get the genie back in the bottle."
Traditional female divers in South Korea, known as "haenyeo", tell the BBC they are anxious.
"Now I feel it's unsafe to dive in," says Kim Eun-ah, who has been doing the job off Jeju Island for six years. "We consider ourselves as part of the sea because we immerse ourselves in the water with our own bodies," she explains.