Trisodium Phosphate in Food: How I Learned to Stop Worrying and Love Paint Thinner

A recent internet freak-out that may have passed under the radar for many out there concerns the presence of a potentially toxic food additive in cereal that is also found in paint thinner and cleaning agents.

The ingredient in question is Trisodium Phosphate (TSP), a salt compound with many diverse uses including paint thinning, cleaning, other degreasing, and removing oxidized metal for soldering. Interestingly, and the source of controversy, TSP is also used as a food additive and a nutritional supplement for exercise.

While this conspiracy theory originally dates back to at least 2014, it has recently made the rounds on social media within the past month. Despite being thoroughly debunked by Snopes the meme continues. This serves as just a single example of an ongoing chemophobia – distrust of anything seen as an unnatural “chemical” – among esteemed internet dietary experts.

Much of TSP’s functionality comes from its strong basicity, as it has a pH=12 as a 1% solution. Its basic properties will promote reaction with fatty acids through saponification, breaking down grease and oil and thus serving as a cleaner and degreaser (or paint thinner). These functionalities also make it useful as a food additive, as its saponification ability is useful in cheese sauces and it can prevent acidification of food. It also prevents moisture buildup and has some antimicrobial properties. Interestingly, it is also used as an exercise enhancer, presumably due to the need for phosphates in aerobic metabolism.

While TSP use has dwindled due to phosphates being recognized as a major contributor to eutrophication (promoting algae growth in water bodies), it is “Generally Recognized As Safe” for human consumption by the US Food and Drug Administration. It can be very corrosive at high concentrations due to its basic properties, however there is no substantial evidence of long-term effects at low doses for TSP or other phosphates.

It is only natural (get it) to be concerned when a chemical involved in industrial processes appears in our food. However while in this case the food additive is in fact the active ingredient in cleaners/degreasers and not merely an unrelated component, it is the concentration and context that matter. The basicity and phosphate chemistry of TSP make it a useful compound for a diverse set of functions, however the chemical reactions necessary for those functions are restricted by the specifics of the chemical concentration, media, and form. It is often the important nuances and details that are left out of a tweet or meme.