Sodium citrate and citric acid are close relatives with different jobs. Citric acid is the acid that dissolves limescale. Sodium citrate is its sodium salt, and what citric acid turns into in alkaline wash water: a phosphate-free builder that holds hard-water minerals so the cleaning ingredients can work. We add it directly to our dishwasher and laundry powders.
Quick facts
- What it is: the sodium salt of citric acid
- Its job in our products: builder and chelating agent
- Where it comes from: made from fermentation-derived citric acid
- EPA Safer Choice: green circle
- Independent safety reviews: HERA (household cleaning) and the Cosmetic Ingredient Review (cosmetics), both below
- CAS number: 994-36-5
The acid descales, the salt keeps minerals busy
Hard water carries calcium and magnesium. Citrate holds those minerals in solution so they cannot tie up surfactants (the ingredients that lift grease and soil) or settle out as scale. That is what a builder does: it takes hard-water minerals out of play so the surfactants work at full strength. The result is better cleaning in hard water, with fewer spots and less film.
It works alongside other builders, such as sodium carbonate, and in Max Strength Laundry Powder with sodium gluconate and sodium polyaspartate. How much of an effect you see depends on the formula and your water hardness.
Where it comes from
Sodium citrate is made by neutralizing citric acid with a sodium base such as sodium hydroxide or sodium carbonate. The citric acid is fermented from sugars by the mold Aspergillus niger; the citric acid page has the details.
Two independent reviews
EPA lists sodium citrate with a green circle under more than one registry number, including 994-36-5 and the anhydrous trisodium form, 68-04-2 (here is how we vet ingredients). EWG's cleaning guide has no exact entry for it, so instead of a grade, here are two independent assessments.
The detergent industry's HERA risk assessment of citric acid and its salts, which covers trisodium citrate, found citrate readily biodegradable and rapidly broken down in sewage treatment and rivers, with low acute toxicity to aquatic life. It concluded household laundry and cleaning use raises no safety concerns for consumers or the environment. Separately, the Cosmetic Ingredient Review expert panel assessed sodium citrate with other citrate salts and concluded they are safe as used in cosmetics at current concentrations.
Handling and safety
As a dry powder, sodium citrate can irritate the eyes. In the wash it dissolves readily and leaves with the rinse water. Use as directed and avoid contact with eyes. If any gets in eyes, rinse cautiously with water for several minutes. If any is swallowed, call Poison Control at 1-800-222-1222. Store powders and tablets dry and sealed in their pouch, up high or in a latched cabinet, out of reach of children and pets.
Where you'll find it
- EWG Verified Dishwasher Tabs
- EWG Verified Dishwasher Powder
- EWG Verified Max Strength Laundry Powder
All three are fragrance-free. Each product page has the full ingredient list.
Sources
- America's Poison Centers. (n.d.). Poison Help. https://poisoncenters.org/
- Fiume, M. M., Heldreth, B. A., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., Liebler, D. C., Marks, J. G., Jr., Shank, R. C., Slaga, T. J., Snyder, P. W., & Andersen, F. A. (2014). Safety assessment of citric acid, inorganic citrate salts, and alkyl citrate esters as used in cosmetics. International Journal of Toxicology, 33(2 Suppl.), 16S-46S. https://doi.org/10.1177/1091581814526891
- HERA Project. (2005). Citric acid and salts (CAS 77-92-9, 5949-29-1, 6132-04-3) (Edition 1.0). Human and Environmental Risk Assessment on Ingredients of Household Cleaning Products. https://www.heraproject.com/substance/citric-acid/
- Max, B., Salgado, J. M., Rodríguez, N., Cortés, S., Converti, A., & Domínguez, J. M. (2010). Biotechnological production of citric acid. Brazilian Journal of Microbiology, 41(4), 862-875. https://doi.org/10.1590/S1517-83822010000400005
- National Center for Biotechnology Information. (n.d.). PubChem compound summary: Trisodium citrate. https://pubchem.ncbi.nlm.nih.gov/compound/Trisodium-citrate
- U.S. Environmental Protection Agency. (n.d.). Safer Choice: Safer Chemical Ingredients List. https://www.epa.gov/saferchoice/safer-ingredients
