Under the waters off the coast of Los Angeles, in the United States, lies a huge health and ecological scandal. In 2020, an LA Times article revealed the presence of dozens of barrels littering the seabed, without anyone knowing what they contained. A few years later, additional research counted 27,000 shapes that could be barrels and more than 100,000 pieces of debris in total, details Live Science.
Between the 1930s and early 1970s, these barrels filled with industrial waste were dumped in 14 deep-water landfills off the coast of Southern California. For forty years, radioactive, chemical, petroleum and explosive waste was deposited there without concern for the consequences on the environment. According to Ouest France, the Montrose Corporation, a Californian chemical manufacturer, dumped more than 2,000 barrels each month.
Until recently, the contents of the majority of these barrels remained a mystery. It was first suggested that the barrels contained dichlorodiphenyltrichloroethane or DDT, a pesticide dangerous for the environment and health, now banned. However, surveys carried out in sediments near five barrels by the team of microbiologist Johanna Gutleben proved that it was not this chemical product.
Waste that makes the sea sterile
This study, the results of which are published in the journal PNAS Nexus, shows that certain substances escaping from this barrel cemetery were strongly alkaline. Indeed, all the samples taken near the barrels displayed an extremely high pH. These caustic alkaline wastes “can damage organic matter and release high concentrations of potentially toxic metals”warn the researchers.
Such substances can come from a multitude of waste linked to the concrete or cement industry, paper mills, the glass industry, ceramics or even the steel industry.
#Decades-old barrels of industrial #Waste off Los Angeles continues to alter the seafloor, creating extreme alkaline environments and reducing microbial and animal diversity for over 50 years. @ucsandiego @PNASNexus https://t.co/XaMOH8xcsU https://t.co/iLwDAYIciC
— Phys.org (@physorg_com) September 9, 2025
The extremely low presence of microbial DNA nearby also indicates that the waste has undoubtedly transformed this area into a hostile environment, devoid of life. Because they persist for more than half a century without dissipating in the ocean, these toxic products must be considered as a sustainable pollutant, likely to have long-term environmental effects, underlines Paul Jensen, co-author of the study.
The specialist said that about a third of the barrels observed so far showed white halos, a sign of the presence of alkaline waste. “We can’t quantify the environmental impact without knowing how many of these barrels with white halos are out there”he concludes. Further research is needed to achieve a full understanding of the consequences of this underwater discharge.
