This story was originally published by Inside Climate News and is reproduced here as part of the Climate Desk collaboration.
In January 1966, a South African ship caught fire at sea, initiating a maritime crisis that would span continents and decades. When the vessel docked in Bristol, England, firefighters pried open a smoking container, causing the conflagration to spread violently and burn unchecked for five days. A little over a month later, a Liberian steamship caught fire near Rotterdam, igniting a storage area filled with barrels of petrol before eventually sinking. The month after that, a Danish ship caught fire off Long Beach, California, injuring three firefighters, killing a longshoreman, and causing over a million dollars in estimated damages.
The common culprit behind each of these catastrophic fires was fishmeal, a dark yellow powder made by drying and pulverizing fish. If left untreated, fishmeal is notorious for spontaneously combusting as it decays and oxidizes. Tied to at least 90 ship and plant fires from the 1950s through the 1970s, the extreme combustibility of fishmeal was a constant, terrifying worry for seafarers, marine insurers, and dock workers, according to a comprehensive sweep of historical news coverage compiled by The Outlaw Ocean Project, a Washington, D.C.-based investigative journalism organization.
In 1967, American feed producer Cargill announced a chemical solution to the crisis: ethoxyquin. Originally developed as a fire retardant to keep rubber tires from drying out and later applied as a preservative on fruits and alfalfa, production of the synthetic antioxidant was rapidly ramped up to meet the demands of the maritime and agricultural sectors.
"Antioxidant treatment has made bulk handling an easy matter," the director of the Canadian Department of Fisheries told an industry publication in 1966, arguing that the chemical treatment should be strictly required for all fishmeal shipments moving across international waters.
The chemical proved to be exceptionally effective at quelling the volatile reactions of the powder. By the 1970s, press-reported fires dropped sharply—falling from a typical 16 ship fires a year, according to data from the Liverpool Underwriters Association, down to just five.
By 1976, the U.S. Coast Guard took formal action by imposing mandatory ethoxyquin treatment on all fishmeal shipments. Three years later, the United Nations body that oversees global maritime activity officially recommended that fishmeal be treated with the chemical "to prevent spontaneous combustion" during transit.
However, a serious and alarming problem soon emerged: Ethoxyquin is a known carcinogen.
"Toxic effects had been observed in laboratory animals fed high concentrations of ethoxyquin," warned a 1969 research paper published by United Nations food and agriculture authorities.
As its use expanded rapidly across animal feeds and modern aquaculture, warning signs multiplied. A 1987 study conducted by British researchers found that the chemical "caused severe damage" and exhibited a potentially "carcinogenic effect" in laboratory rats. Decades later, in 2015, the European Food Safety Authority issued a stark assessment stating that an impurity within ethoxyquin, known as p-phenetidine, was capable of causing direct mutations in genetic material.
While a definitive scientific consensus remains elusive on whether it is safe for humans to routinely eat farmed seafood raised on feed treated with ethoxyquin, several nations have considered the potential health risks to be high enough to justify banning or strictly limiting the chemical’s use. In 2017, the European Commission officially suspended authorization for its use in animal feed across the entire European Union.
Today, ethoxyquin has been completely banned in the United Kingdom and by members of the European Economic Area, including Norway, Iceland, and Liechtenstein. Yet, ethoxyquin—within established regulatory limits—is still permitted in animal feed in countries such as Australia, Japan, South Korea, and the United States.
With more than half of the seafood eaten worldwide now coming from fish farms, and with the vast majority of those farmed species fed diets rich in fishmeal and fish oil, studying the chemical additives blended into feed has become critical for understanding potential contamination within the global food supply chain.
Although ethoxyquin is not banned in the United States, it has found itself at the center of at least a half-dozen civil lawsuits, typically involving allegations of false advertising and consumer deception. Some of these lawsuits targeted major seafood companies for marketing their products as "sustainable" even though testing revealed they contained ethoxyquin, while others highlighted the potential environmental risks that the industrial additive poses to vulnerable aquatic ecosystems.
In 2022, a New York resident filed a class-action lawsuit against Aldi Inc., a major German supermarket chain with extensive operations across the United States, alleging that its Atlantic salmon products were falsely labeled as "sustainable" due to reliance on "environmentally destructive" industry practices. The legal complaint cited the European Union’s strict ban on the chemical along with scientific studies linking ethoxyquin to mortality and physical deformations in fish and crustaceans, noting that the chemical "poses a risk for aquatic life." The case was ultimately settled out of court.
That same year, a New York resident and a California resident jointly filed a similar lawsuit against Gorton’s Inc., a prominent seafood company, for labeling its frozen tilapia products as "sustainably sourced" despite the presence of ethoxyquin. This lawsuit also cited the inherent "risk for aquatic life" and the European Union’s regulatory ban, and it too was eventually settled out of court.
Regulatory oversight varies wildly across international borders. In Canada, the national Food Inspection Agency requires animal feeds containing ethoxyquin to carry a clear label declaring that the product meets legal safety limits, but the agency does not specify how or how often it tests commercial feeds for the chemical. Furthermore, federal inspectors do not routinely check whether ethoxyquin residues ultimately end up in the consumable seafood itself, according to the agency’s latest food inspection report from 2022.
Adding to concerns about regulatory enforcement, a 2024 audit of the Canadian food inspection agency conducted by the European Union revealed that the agency completed only about 40 percent of its planned inspections, citing "systematic and significant under-delivery" regarding the testing of imported and domestic seafood products.
Industry players, meanwhile, have sought to distance themselves from the controversial compound. Cargill stated in a public announcement that it has actively assessed alternative antioxidants since 2005 and no longer uses ethoxyquin in its global salmon feed business or in any market where the chemical is not explicitly authorized for use in aquafeed. The company also emphasized that it did not originally develop ethoxyquin. Globally, commercial feed makers and agricultural producers have increasingly shifted toward alternative additives, including natural options such as rosemary extract and various vitamin E compounds.
"More and more destinations are not accepting ethoxyquin, starting with our local Peruvian market," said James Frank, managing director of the Peruvian fishmeal company MSICeres, during a 2022 industry webinar. He noted that 100 percent of Peru’s massive fishmeal exports destined for Europe, Canada, the United States, and Australia are now entirely ethoxyquin-free, mirroring a supply chain shift already adopted by major companies in the United Kingdom and Norway.
However, replacing ethoxyquin has presented its own set of chemical challenges. The most popular commercial alternative to ethoxyquin is currently butylated hydroxyanisole, widely known as BHA, which is favored by manufacturers for its lower production costs and strong antioxidant properties compared to fully natural additives. But much like the chemical it aims to replace, BHA carries its own significant health risks, according to independent toxicological researchers.
The U.S. National Toxicology Program identified BHA as "reasonably anticipated to be a human carcinogen" as early as 1991, and Japanese researchers published findings in 2008 showing that the preservative caused malignant tumors in laboratory rats.
Amid growing health and regulatory scrutiny, the U.S. Food and Drug Administration announced a formal reassessment of the safety of BHA as a common food preservative.
To address the world’s insatiable global appetite for seafood, the commercial aquaculture industry will undoubtedly continue to expand in the coming decades. Industry analysts suggest there may eventually be a structural shift away from carnivorous farmed fish species, or that safer, truly benign replacements for fishmeal will be successfully engineered. But for now, the modern aquaculture and fishmeal industries find themselves locked in a perilous cycle: pivoting desperately away from deadly ship fires, turning to a carcinogenic fire retardant, and subsequently searching for yet another temporary fix.