In the 1940s and 1950s, the ocean off the coast of Los Angeles was a dumping ground for the nation's largest manufacturer of the pesticide DDT—a chemical now known to harm humans and wildlife. Due to the stubborn chemistry of DDT and its toxic breakdown products, this pollution continues to plague L.A.'s coastal waters more than half a century later. While legal at the time, details of this industrial-scale pollution of the marine environment at a dump site some 15 miles offshore near Catalina Island have deeply concerned scientists and the public since they gained wider recognition in 2020.

In the 1940s and 1950s, the ocean off the coast of Los Angeles was a dumping ground for the nation’s largest manufacturer of the pesticide DDT—a chemical now known to harm humans and wildlife. Due to the stubborn chemistry of DDT and its toxic breakdown products, this pollution continues to plague L.A.'s coastal waters more than half a century later.

While legal at the time, details of this industrial-scale pollution of the marine environment at a dump site some 15 miles offshore near Catalina Island have deeply concerned scientists and the public since they gained wider recognition in 2020.

“We are still seeing this DDT contamination in deep-sea organisms and ocean sediments more than 50 years after they were dumped there,” said Hoh. “I’m not sure if that company expected the consequences of their pollution to last this long, but they have.”