Is one of our toxic Superfund sites missing?

An estimated 110 tons of deadly DDT, lying for years on the ocean floor off the coast of Palos Verdes, California, has been recalculated to be around 14 tons, according to a report in Environmental Health News. And no one is quite sure what happened.

The once-ubiquitous pesticide, now banned, has been around that area for awhile. It was dumped in sewers by the Montrose Chemical Corporation DDT manufacturing plant that operated in nearby Torrance from 1947 to 1983. The U.S. Environmental Protection Agency (EPA) estimated that more than 1,700 tons were discharged into the ocean.

DDT (dichlorodiphenyltrichloroethane) is a colorless pesticide that was used during World War II to control malaria and widely afterward in agriculture and homes. The untested chemical was thought to be safe by the general public until Rachel Carson published an essay entitled “Silent Spring” in New Yorker magazine in 1962, igniting a firestorm of debate that launched the modern American environmental movement. The U.S. banned most uses of DDT in 1972.

DDT is toxic to a wide range of marine life, although it is thought to be less toxic to human beings.

The area southwest of Los Angeles was declared a Superfund site in 1997. Three years later, the EPA ran a pilot program to test if the DDT field could be capped and in 2009 made an “interim” decision to go forward with it sometime in the future. The project was expected to cost $60 million and was considered one of the more technically challenging of the nation’s 1,200 or so Superfund sites.

But you can’t cap what you can’t find.

The contamination could have been overestimated before, underestimated now or unexpectedly dechlorinated into something harmless (eaten by microbes?). Or the pesticide could have dissipated into the water where it would be absorbed by all manner of creatures.

The waters off Palos Verdes have been used by sport and commercial fishermen. Other activities include boating, swimming, windsurfing, surfing and scuba diving.

-Ken Broder

To Learn More:

Going, Going, Gone? Vanishing DDT Is Big Surprise at Ocean Deposit off Los Angeles (by Marla Cone, Environmental Health News)

Top 5 Things You Need to Know About the Palos Verdes Shelf Superfund Site (Fish Contamination Education Collaborative)

Palos Verdes Shelf (U.S. Environmental Protection Agency)