Sodium Tri Poly Phosphate | STPP
In Bhutan

Uses In Detergents:
The majority of STPP is consumed as a component of commercial detergents. It serves as a "builder," industrial jargon for a water softener. In hard water (water that contains high concentrations of Mg2+ and Ca2+), detergents are deactivated. Being a highly charged chelating agent, TPP5- binds to dications tightly and prevents them from interfering with the sulfonate detergent.

Food Applications:
STPP is a preservative for seafood, meats, poultry, and animal feeds.
It is common in food production as E number E451. In foods, STPP is used as an emulsifier and to retain moisture. Many governments regulate the quantities allowed in foods, as it can substantially increase the sale weight of seafood in particular. The United States Food and Drug Administration lists STPP as "generally recognized as safe.".

Other Uses:
Other uses (hundreds of thousands of tons/year) include "ceramics, leather tanning (as masking agent and synthetic tanning agent - SYNTAN), anticaking, setting retarders, flame retardants, paper, anticorrosion pigments, textiles, rubber manufacture, fermentation,antifreeze."

TPP is used as a polyanion crosslinker in polysaccharide based drug delivery.

Health Effects:
Polyphosphates are hydrolyzed into simpler phosphates, which in moderate amounts are nutritious. For example, ATP, a related derivative of triphosphate, is essential for life. Thus, the toxicity of polyphosphates is low, as the lowest LD50 after oral administration is >1,000 mg/kg body weight. Similarly, no mutagenic or carcinogenic effects nor reproductive effects have been noted. Salts of polyphosphate anions are moderately irritating to skin and mucous membrane because they are mildly alkaline.