Sea Grant Programs Award $5.2 Million in State Funding to Address Deep Ocean DDT Contamination in Southern California


California (CA) Sea Grant and University of Southern California (USC) Sea Grant have received just over $5.2 million in funding from the State Water Resources Control Board (State Water Board) to fund four new projects to give the state a greater understanding of the human health risk and ecological risk due to deep ocean DDT+ deposits (i.e., ocean disposal sites, other coastal sources, and DDT processes) in the Southern California Bight. 

“The Los Angeles Water Board is encouraged to see the California Deep Ocean DDT+ research proposals selected for funding by the State Water Board and Sea Grant,” says Los Angeles Water Board Chair, Norma Camacho. “The Los Angeles Region and Southern California are blessed with productive and important ecosystems, including the Southern California Bight. However, the more than 20 million people and treasured wildlife who call this place home are burdened with a long legacy of DDT pollution. The completion of these projects will help us understand the human health risk and ecological risks due to deep ocean DDT+ deposits and find the best ways to restore our environment and protect the people who live here.”

DDT is an insecticide banned in 1972 for its harmful impacts on wildlife and potential carcinogenic effects on humans. Recent field surveys have renewed interest in research to understand the extent, impacts, and risks of deep ocean DDT in the Southern California Bight, particularly as new methodologies have revealed a greater diversity of DDT breakdown compounds and related byproducts (hereafter referred to as “DDT+”) of unknown impacts and extent. 

In response, USC and CA Sea Grant Programs conducted a community-driven research needs assessment in 2022, engaging diverse perspectives from across the state, culminating in A Deep Ocean DDT+ Research Needs Assessment for the Southern California Bight in January 2023 and a public-friendly storymap of the results. The State Water Board, in coordination with CA and USC Sea Grants, issued a request for proposals in January 2023. 

“This work is challenging, but timely and necessary,” says Dr. Lian Guo, CA Sea Grant’s Research Coordinator. “Conducting research in deep ocean environments requires cutting-edge laboratory techniques and technology, but the chosen projects have collaborative and multi-institutional designs that enable them to tackle a significant amount of work in just 18 months.” 

These projects join a portfolio of research being conducted to assess the scope and impacts of deep ocean disposal of DDT+ in Southern California. The new research projects, focused on state information and management needs, will complement ongoing federally-funded research at Scripps Institution of Oceanography

“These four awarded projects will provide a critical foundation for future work. The complexity of this challenge necessitates continued researcher and community involvement, as well as sustained research funding, to address the full suite of deep ocean DDT+ research needs outlined in our report,” says Dr. Amalia Almada, USC Sea Grant’s Science, Research & Policy Specialist. 

The four awardees of the 2023-2024 California State Funding for Deep Ocean DDT+ are:

Foundational Research for Deep Ocean Dumping of DDT+ Wastes: How much is out there, where is it, and what is it doing today?

Project Lead: David Valentine, University of California Santa Barbara

Co-PIs: Eunha Hoh (San Diego State University); Nathan Dodder (San Diego State University)

Summary: Recent analysis has confirmed that DDT+ bulk waste was not contained in barrels, and that some was likely “short dumped” between the California mainland and designated legal dumpsites in the San Pedro and Santa Monica Basins. Through field, laboratory, and analytical efforts, Valentine and collaborators will determine the quantity and spatial extent of this pollution, and the potential for degradation, movement, or interaction with living organisms. The research team will quantify the diversity of DDT+ products within sediment core samples and model timescales of DDT+ degradation, as well as mechanisms of transport from sediments. 

Project Administrator: USC Sea Grant

The production and mobility of DDT metabolites within sediments as controlled by the local diagenetic environment

Project Leads: William Berelson, University of Southern California

Co-PIs: Alex Sessions (California Institute of Technology); Hope Alisa Johnson, (CSU Fullerton); Lisa Collins (Santa Monica College)

Summary: Currently, there is no routine analytical method for sensitively measuring concentrations of most of the known DDT+ breakdown products and related byproducts. Berelson and partners will develop an identification and quantification method for at least 23 DDT+ compounds at very low concentrations at various ocean depths. Berelson will also investigate whether “fingerprinting” (‘isotomics’) of DDT sources is possible—in other words, this work will reveal if it will be feasible to trace DDT contamination from marine animals back to exact sources of DDT contamination on the seafloor. Berelson will weave the various threads of this project together into a model depicting DDT+ migration in deep water sediments. The produced model and novel analytical techniques will be critical for accurate and efficient future risk assessments for human and ecological health.

Project Administrator: USC Sea Grant

Assessment of Highly Mobile Coastal Elasmobranchs as Vectors of DDT to Low-Income Communities

Project Lead: Christopher Lowe, California State University Long Beach 

Co-PIs: Varenka Lorenzi (California State University Long Beach), Ryan Freedman (NOAA Channel Islands NMS), Kady Lyons (Georgia Aquarium)

Summary: Scientists have known for decades that DDT accumulates in fatty tissues of organisms, and this accumulation magnifies higher up the food web. However, studies to date have focused on high-market-value fish, while comparatively less information exists about cheaper commercial species or subsistence fishing targets, like smaller sharks and rays, despite the fact many of these species spend significant time near DDT+ contaminated sediments. This project will quantify DDT+ contaminants in the tissues of Angel Sharks, Bat Rays, and Leopard Sharks in southern California; determine the spatial distribution of these species using satellite and acoustic tags to understand habitat use near DDT-contaminated sites; and determine the potential exposure risk from consumption of these species by at-risk or low-income communities. This project will integrate partnerships with anglers and a nonprofit called Heal The Bay that leads a local Angler Outreach Program. 

Project Administrator: California Sea Grant

Hazard assessment of deep ocean DDT disposal: Defining biomagnified DDT+ chemical profiles and investigating the health impacts on sentinel wildlife species and humans

Project Leads: Eunha Hoh, Karilyn Sant, and Nathan Dodder, San Diego State University

Co-PIs: Rebecca Duerr (International Bird Rescue), Pádraig Duignan (The Marine Mammal Center), Alissa Deming (Pacific Marine Mammal Center), Christopher Tubbs (San Diego Zoo Wildlife Alliance); Myra Finkelstein (University of California Santa Cruz), Frances Gulland (UC Davis)

Summary: Relatively high levels of approximately 45 DDT+ compounds recently were identified in southern California marine mammals. However, data on the unique exposure and health risks near the deep ocean DDT+ sites are particularly limited. Hoh and project partners will examine southern California wildlife to assess their current levels of DDT+ and whether these change over time or by geographical distance, and whether there are correlations with health issues. Overall, the team aims to examine the reproductive and developmental toxicity of DDT+ using model systems to help assess the risks to human health. The project team plans to further engage Indigenous high school students in the research project and develop a children’s book about deep ocean DDT+.

Project Administrator: California Sea Grant

CA and USC Sea Grants are part of a national network of 34 university-based programs administered by the National Oceanic and Atmospheric Administration. 

Media Contacts

Lian Guo, CA Sea Grant Research Coordinator, (

Leah Shore, USC Sea Grant Communications Manager (; 213-740-1960)