As many as half a million of these barrels could still be underwater right now, according to interviews and a Times review of historical records, manifests and undigitized research. From 1947 to 1982, the nation’s largest manufacturer of DDT — a pesticide so powerful that it poisoned birds and fish — was based in Los Angeles.
Shipping logs show that every month in the years after World War II, thousands of barrels of acid sludge laced with this synthetic chemical were boated out to a site near Catalina and dumped into the deep ocean — so vast that, according to common wisdom at the time, it would dilute even the most dangerous poisons.
Regulators reported in the 1980s that the men in charge of getting rid of the DDT waste sometimes took shortcuts and just dumped it closer to shore. And when the barrels were too buoyant to sink on their own, one report said, the crews simply punctured them.
In 1972, the U.S. finally banned the use of DDT.
Demand was still strong in other countries, however, so the chemical plant in Los Angeles kept churning out more.