This toxic adulterant in edible oils can damage your nervous system: Here's how to check if your cooking oil is safe

Most people worry about calories when they reach for their cooking oil. Very few think to worry about paralysis. But there is a chemical adulterant that has caused mass poisoning events across multiple continents, left tens of thousands of people permanently disabled, and has been found in edible oils in India. It's called tri-ortho-cresyl phosphate, or TOCP, and it has no place in food.

So what is it, how does it get into cooking oil, and what can you actually do about it at home? Here's what you need to know.

TOCP is an organophosphorus compound primarily used in industrial settings as a lubricant, plasticiser, and jet engine oil additive.

TOCP is highly toxic and can induce neurotoxicity, reproductive toxicity, and immunotoxicity. Most critically, it causes a delayed neurodegenerative condition known as organophosphate-induced delayed neurotoxicity, which affects both the central and peripheral nerves and can result in permanent damage to the neurological system.

This isn't theoretical. The damage TOCP can do has been documented in outbreak after outbreak over more than a century. In 1930, TOCP was added to an alcoholic beverage in the United States, leaving between 20,000 and 100,000 people permanently affected. Early symptoms included numbness and tingling in the extremities, with partial permanent paralysis at higher doses.
In 1959, Morocco experienced an epidemic of paralysis after poor Arab families unknowingly cooked with olive oil adulterated with TOCP, which had been acquired cheaply as a jet engine flushing fluid. By the end of that outbreak, over 10,000 individuals had been afflicted.
India has not been spared. Outbreaks of TOCP-induced delayed neurotoxicity have been reported in Mumbai, where 58 patients were affected, and four subsequent outbreaks were documented in Bengal. Patients presented with cramping muscle pain, numbness, progressive weakness in the limbs, and in severe cases, spasticity and loss of function in both legs and arms.

FSSAI has developed a rapid testing programme called DART, which stands for Detect Adulteration with Rapid Test, specifically designed so that consumers can check common adulterants without laboratory equipment.
For TOCP specifically, the FSSAI-recommended test involves taking 2ml of the oil sample and adding a small amount of solid yellow butter to it. If red colour forms immediately, it indicates the presence of TOCP in the oil. It's a simple, inexpensive test that takes under a minute and can be done in any kitchen.
Beyond the TOCP-specific test, there are broader checks worth doing with any cooking oil. A refrigerator test is useful: place oil in a glass in the fridge for two to three hours. Pure oils show uniform thickening, while adulterated oils often separate into cloudy layers. A visual clarity check also helps since pure oils are generally transparent and consistent in colour. Anything that looks murky, has an unusual odour, or separates unexpectedly warrants caution.
For oils sold loose or in unlabelled containers, the risk is significantly higher. India has a documented history of oil adulteration, including the 1998 Delhi mustard oil poisoning that killed 60 people and made over 3,000 ill. Buying oil in sealed, branded, FSSAI-licensed packaging with a clearly marked batch number and manufacturing date isn't a guarantee, but it substantially reduces the risk.