For years industrial companies in southern California used the coast as a dumping ground for toxic chemical waste, including DDT. Decades later, scientists have found that the pesticide remains in high concentrations on the ocean floor and has never broken down.
Nearly two years after the discovery of tens of thousands of barrels of waste off the coast of Los Angeles, a scientist working on the issue shared this week that the chemical is still spread across a massive stretch of the seafloor, the Los Angeles Times reported.
\u201cWe still see original DDT on the seafloor from 50, 60, 70 years ago, which tells us that it\u2019s not breaking down the way that [we] once thought it should,\u201d David Valentine, a UC Santa Barbara scientist, said. The LA Times reported that the contamination covered an area of seafloor larger than the city of San Francisco. \u201cAnd what we\u2019re seeing now is that there is DDT that has ended up all over the place, not just within this tight little circle on a map that we referred to as dumpsite two.\u201d
DDT, which was widely used in the US as an agricultural pesticide and sprayed in large quantities at beaches to kill mosquitoes, has been linked to cancer and disease in humans and the mass die-off of animals. In the 1970s, it was banned in the US due to its harmful effects on wildlife and potential risks to humans. Research has shown a link between exposure to the chemical and breast cancer as well as reproductive problems.
Southern California was the center of DDT production in the US. The Montrose Chemical Corporation in Torrance produced massive amounts of the chemical between the end of the second world war through 1982. During that time, before Congress banned such activity, up to 2,000 barrels a month of acid sludge waste containing DDT were dumped off the coast. Workers sometimes poked holes in the barrel so they would sink more quickly.
In late 2020, a report from the LA Times told the story of how LA\u2019s coast became a dumping ground for DDT, revealing that as many as half a million barrels could still be on the sea floor, prompting Senator Dianne Feinstein to ask the EPA to take action.
A two-week survey, conducted in 2021 by a team from the Scripps Institution of Oceanography at University of California, San Diego and the National Oceanic Atmospheric Administration, using seafloor robots, sonar acoustic imagery and data helped reveal the scale of the issue, finding more than 25,000\u2002barrels. Scientists identified more than 100,000 manmade items across the entire survey area.
\u201cTrawls, cable lays, could reintroduce this stuff back up to the surface,\u201d Valentine told the newspaper. \u201cAnd animals feeding \u2013 if a whale goes down and burrows on the seafloor, that could kick stuff up.\u201d
DDT has already been linked to continued harmful affects on wildlife. On the central California coast, which also served also a dumping ground for DDT, a 20-year-long study found a link between exposure to contaminants and high rates of cancer and herpes in sea lions.
Congress has allotted millions of dollars toward researching the issue. \u201cThe federal funding we secured will be significant for advancing research to understand the scope and scale of DDT pollution off the coast of southern California,\u201d Feinstein said on Twitter. \u201cWe must act quickly to clean this up.\u201d<\/p>\n\n\n\n