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Sodium Tripolyphosphate

  • Chelators
  • CAS 7758-29-4
  • IUPAC: Pentasodium triphosphate

Sodium Tripolyphosphate (CAS 7758-29-4) appears in 2 of the 1,812 car-care products CarCareTruth tracks (as of June 2026). It is readily biodegradable.

GHS-unclassified as used in dilute consumer formulas. May cause mild irritation to eyes and skin with direct contact to concentrate form. HMIS Health rating 0–1 at typical working dilution. Not a respiratory sensitizer; not Prop 65 listed.

Sodium tripolyphosphate (STPP) is an inorganic polyphosphate salt used as a builder and water softener in cleaning formulas. It sequesters calcium and magnesium ions that would otherwise reduce surfactant effectiveness, making it a common co-ingredient with nonionic surfactants in alkaline fabric and carpet cleaners.

Why it matters in fabric cleaners: STPP improves the cleaning efficiency of surfactant systems in hard-water conditions by preventing soap scum formation. It buffers the cleaning solution pH and helps suspend soils for extraction. At the low concentrations typical in RTU spray cleaners, STPP presents minimal health risk.

Environmental note: Phosphates in wastewater can contribute to algal eutrophication in sensitive water bodies. This concern is primarily relevant to high-volume commercial laundering rather than the trace residues left by spot-cleaning a vehicle interior.

Regulatory status

  • Not CA Prop 65 listed
  • Listed on TSCA inventory; no use restrictions for consumer cleaning products in the US
  • EPA has restricted STPP in laundry detergents in some US states due to phosphate eutrophication concerns; restrictions do not apply to automotive fabric cleaners

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
yes
Bioaccumulative
no
Persistent
no
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
5/5
Purpose: Water softener and cleaning builder; sequesters calcium and magnesium ions to prevent scale and improve surfactant efficiency in alkaline cleaners

Common questions about Sodium Tripolyphosphate

What is Sodium Tripolyphosphate used for in car care?
Water softener and cleaning builder; sequesters calcium and magnesium ions to prevent scale and improve surfactant efficiency in alkaline cleaners
Is Sodium Tripolyphosphate a VOC?
No. Sodium Tripolyphosphate is not classified as a volatile organic compound (VOC).
Is Sodium Tripolyphosphate on California's Proposition 65 list?
No. Sodium Tripolyphosphate is not on California's Proposition 65 list.
Is Sodium Tripolyphosphate biodegradable?
Yes. Sodium Tripolyphosphate has a confirmed biodegradable profile.

2 products contain this

Related

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.