A few weeks ago, I was reporting that the Runit Dome had some cracks in the concrete from where the nuclear waste stored in it was most probably leaking into the open ocean.

Now researchers have found high levels of radiation in giant clams near the Central Pacific site where the United States entombed waste from nuclear testing almost four decades ago, raising concerns the contamination is spreading from the dump site's tainted groundwater into the ocean and the food chain.

The findings from the Marshall Islands suggest that radiation is either leaking from the waste site — which U.S. officials reject — or that authorities did not adequately clean up radiation left behind from past weapons testing, as some in the Marshall Islands claim.

The radioactive shellfish were found near Runit Dome — a concrete-capped waste site known by locals as "The Tomb" — according to a presentation made by a U.S. Department of Energy scientist this month in Majuro, the island nation's capital. The clams are a popular delicacy in the Marshall Islands and in other nations, including China, which has aggressively harvested them from vast swaths of the Pacific.