A new report in the Los Angeles Times indicates that pollution in the Pacific Ocean off the California coast could be even more dangerous than originally thought.

What was once thought to be thousands of barrels of DDT may actually be low-level radioactive waste, and the DDT that was detected was not contained in barrels at all, but rather poured directly into the ocean, according to researchers.

Instead, scientists believe that between the 1940s and 1960s, “local hospitals, labs and other industrial operations [disposed of] barrels of tritium, carbon-14 and other similar waste at sea,” the Times reported on Wednesday.

The numbers of such disposals are staggering.

One map from the International Atomic Energy Agency said that over a 25-year period ending in 1970, “more than 56,000 barrels of radioactive waste had been dumped into the Pacific Ocean on the U.S. side” alone.

Scientists have spotted some of those barrels under more than 3,000 feet of water near Catalina Island, a place they’re likely to stay.