Pentasodium triphosphate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Dose descriptor:

NOAEL

141 mg/kg bw/day

Additional information

In the prenatal developmental toxicity studies, pregnant females received STPP (anhydrous) during gestation period by oral intubation. Control groups received the vehicle only (water). At the end of gestation period, all dams were subjected to caesarean section and the number of implantation sites, resorption sites, as well as live and dead foetuses were recorded. The body weights of the live pups were taken. The urogenital tract level of dams was examined for abdominal abnormalities. All foetuses were examined for the presence of external congenital abnormalities. One-third of the foetuses were examined for visceral abnormalities and the remaining two-third were examined for skeletal abnormalities. No maternal toxicity or teratogenic effects were observed at up to the maximum dose levels tested in each species. The NOEL for maternal and foetal toxicity corresponded to the maximum dose tested.

Summary of teratogenicity studies with sodium tripolyphosphate

-	animal / group	Dose (mg/kg bw)	Treatment period (gestation day)	End of gestation	Result (NOEL)
Mouse	24	2.4, 11, 52, 238	6-16	Day 17	238 mg/kg
Rat	24	1.7, 8, 37, 170	6-15	Day 20	170 mg/kg
Hamster	22-25	1.41, 6.5, 30, 141	6-10	Day 14	141 mg/kg
rabbit	20-22	2.5, 11.6, 54, 250	6-18	Day 29	250 mg/kg

Short description of key information:
A series of four prenatal developmental toxicity studies were performed by the US food and drug administration (rabbit, mouse, rat and hamster). Sodium tripolyphosphate was not found to be a teratogen at any of the dose levels tested.
A 3-generation study in rats is available (Hodge et al., 1959). At a dose of 0.5% in the food, STPP showed no evidence of significant alteration of fertility, nor on the litter size, nor on growth and survival of offspring. A slight increase in kidney weights was observed, but was not statistically significant. The macroscopic and microscopic appearances of major organs in the 3rd generation were reported to be comparable in control and treated groups. These results were presented as a summary of unpublished reports from a detergent company, and limited documentation was available. However, any significant effects seem to have been reported by the author. The results provided support the assumption that there is no concern with regard to effects of STPP on reproduction.

Effects on developmental toxicity

Description of key information

Based on the three-generation reproduction study on STPP (Hodge, 1959), no effects on reproductive performance or fertility were found when STPP was administered to rats for three generations at a dose of 0.5% in the diet with at least two litters per generation

Additional information

The Hodge reproduction study (1959) was conducted prior to the institution of good laboratory practice guidelines and to the current OECD Guideline 416. Therefore, the study has deficiencies when examined according to today’s standards. The study is considered a Klimisch Code 2, reliable with restrictions. The conclusions regarding the hazard identification of STPP are supported by data on sodium hexametaphosphate (SHMP) and sodium trimetaphosphate (STMP), both of which are structurally similar to STPP. All three inorganic phosphate salts had no adverse effects on reproductive toxicity and fertility when tested in rats over three generations (Hodge 1959, 1960). 

In theManual for Investigation of HPV Chemicals, Chapter 3: Data Evaluation (2005), Section 3.1.6 Weight-of-the-Evidence Analysis, requires the use of a weight-of-the-evidence analysis during the assessment of data quality and adequacy.  The guidance permits the pooling of several studies, one or more of which may be inadequate, to satisfy a specific SIDS element. In the current case, available data exist on two other sodium inorganic phosphate salts which are similar in structure to STPP.  Three generation reproduction studies have been conducted on SHMP and STMP which are similar to the one on STPP in that they were conducted prior to good laboratory practice guidelines and the existence of OECD Guideline 416; nevertheless, they provide additional supplemental support for the hazard assessment of STPP (IUCLID Robust Study Summary included as supplemental information). Because all three sodium phosphates showed no effects on reproductive performance, these data show similar responses which allows a more robust conclusion for the individual salts. STPP and SHMP were both tested at a dose level of 0.5% in the diet. STMP was tested at a dose of 0.05% in the diet. These dose levels were viewed as appropriate levels based on the results of the chronic toxicity/carcinogenicity studies for each salt.