of polyphosphate anions are moderately irritating to skin and mucous membranes because they are mildly alkaline. Environmental effects Because it is very water-soluble, STPP is not significantly removed by waste water treatment. STPP hydrolyses to phosphate, which is assimilated into the natural phosphorus cycle. Detergents containing phosphorus contribute to the eutrophication of many fresh waters. See also Sodium trimetaphosphate, a cyclic triphosphate Acceptable daily intake References Food additives Sodium compounds Phosphates E-number additives