Radioactive waste historically dumped off L.A. coast [Video]

For decades, a graveyard of corroding barrels has littered the seafloor just off the coast of Los Angeles. It was out of sight, out of mind — a not-so-secret secret that haunted the marine environment until a team of researchers came across them with an advanced underwater camera.

Speculation abounded as to what these mysterious barrels might contain. Startling amounts of DDT near the barrels pointed to a little-known history of toxic pollution from what was once the largest DDT manufacturer in the nation, but federal regulators recently determined that the manufacturer had not bothered with barrels. (Its acid waste was poured straight into the ocean instead.)

Now, as part of an unprecedented reckoning with the legacy of ocean dumping in Southern California, scientists have concluded the barrels may actually contain low-level radioactive waste. Records show that from the 1940s through the 1960s, it was not uncommon for local hospitals, labs and other industrial operations to dispose barrels of tritium, …