Reported in EPA TSCA Inventory.

Sodium metaphosphate, its cas register number is 10124-56-8. It also can be called Graham's salt; Sodium phosphate (Na₆P₆O₁₈); Sodium phosphate, tribasic; Sodium polymeta phosphate; Metaphosphoric acid (H₆P₆O₁₈), hexasodium salt; Metaphosphoric acid (H₆P₆O₁₈), sodium salt (1:6); Metaphosphoric acid, hexasodium salt; Sodium metaphosphate; Sodium phosphate, tribasic. It is a white granular solid. It hydrolyzes in aqueous solution, particularly under acidic conditions, to sodium trimetaphosphate and sodium orthophosphate. It can be prepared from Na₂HPO₄ and NaH₂PO₄.

Uses of Sodium metaphosphate:  Sodium metaphosphate is used as a sequestrant and has applications with in a wide variety of industries, including as a food additive in which it is used under the E number E452i. Its products are used for water softening and detergents, when added with sodium carbonate. It is also used as a dispersing agent to break down clay and other soil types.One of the lesser-known uses for Sodium metaphosphate is as a deflocculant in the making of Terra sigillata, a ceramic technique using a fine particled slip. However, it is also a whitening ingredient included in some whitening toothpastes and mouthwashes.

You can still convert the following datas into molecular structure:
(1)InChI=1S/6Na.H6O18P6/c;;;;;;1-19(2)13-20(3,4)15-22(7,8)17-24(11,12)18-23(9,10)16-21(5,6)14-19/h;;;;;;(H,1,2)(H,3,4)(H,5,6)(H,7,8)(H,9,10)(H,11,12)/q6*+1;/p-6;
(2)InChIKey=GCLGEJMYGQKIIW-UHFFFAOYSA-H;
(3)SmilesP1(OP(OP(OP(=O)([O-])OP(OP(O1)(=O)[O-])(=O)[O-])(=O)[O-])(=O)[O-])(=O)[O-].[Na+].[Na+].[Na+].[Na+].[Na+].[Na+];

The toxiciy data is as follows: