Pentapotassium triphosphate

Endpoint summary

Description of key information

One key study is available (Bradshaw J - 2008) for the skin sensitisation endpoint. This study is performed on an analogous substance; pentasodium triphosphate / STPP and conducted to the appropriate guideline (OECD 249, Local Lymph Node Assay) and under the conditions of GLP. The study is therefore considered to be a reliability 1 study (according to the Klimisch scale).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
See read-across justification report under Section 13 ‘Assessment Reports’.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
In accordance with REACH Annex XI, Section 1.5, of Regulation (EC) No. 1907/2006 (REACH) the standard testing regime may be adapted in cases where a grouping or read-across approach has been applied.

The similarities may be based on:
(1) a common functional group
(2) the common precursors and/or the likelihood of common breakdown products via physical or biological processes, which result in structurally similar chemicals; or
(3) a constant pattern in the changing of the potency of the properties across the category

1. Both substances are inorganic salts of a monovalent cation from Group 1A of the periodic table, and triphosphoric acid. Thus, they share the Na+ or K+ cation and P3O105- anion.
2. As both substances contain the same anion, any sensitisation potential from the anion will be the same for both compounds.
3. Sodium and potassium are both group 1 alkali metals, the ionic charges are the same and the chemical behaviour will be similar. Potassium has a larger ionic radius and as penetration of the skin is largely governed by molecular size, the ability of potassium to penetrate the skin is likely to be less than sodium. As the chemical behaviour of both the anion and the cation will be similar and the dermal absorption of the cation is likely to be reduced, the negative results from pentasodium triphosphate can reliably be read across to pentapotassium triphosphate.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See read-across justification report under Section 13 ‘Assessment Reports’.

3. ANALOGUE APPROACH JUSTIFICATION
See read-across justification report under Section 13 ‘Assessment Reports’.

4. DATA MATRIX
See read-across justification report under Section 13 ‘Assessment Reports’.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan UK limit
- Age at study initiation:
- Weight at study initiation: 15-23g
- Housing: individually in suspended solid floor polypropylene cages
- Diet (e.g. ad libitum): certified rat and mouse diet ad libitum
- Water (e.g. ad libitum):mains tap water ad libitum
- Acclimation period: 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 25-30
- Humidity (%): 19-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light):12/12


IN-LIFE DATES: From: 04/03/2008 To: 26/04/2008

Vehicle:

other: 1% pluronic L92 in distilled water

Concentration:

1, 2.5 and 5%

No. of animals per dose:

4

Details on study design:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method:LLNA
- Criteria used to consider a positive response:Test material regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in HTdR incorporation compared to control values


TREATMENT PREPARATION AND ADMINISTRATION: Freshly prepared in 1% pluronic L92 in distilled water
daily application of 25µl of 1, 2.5 or 5% w/w test material

Positive control substance(s):

other: 2,4-Dinitrobenzenesulfonic acid, sodium salt

Positive control results:

2,4-dinitrobenzenesulfonic acid, sodium salt in 1% pluronic L92 in distilled water
Concentration, Stimulation index, Result
1%, 1.80, Negative
5%, 4.32, Positive
10% , 11.98, Positive

Key result

Parameter:

SI

Value:

1.27

Test group / Remarks:

1% w/w in vehicle

Key result

Parameter:

SI

Value:

1.17

Test group / Remarks:

2.5% w/w in vehicle

Key result

Parameter:

SI

Value:

1.31

Test group / Remarks:

5% w/w in vehicle

Table 1. Results of the Local Lymph Node Assay.

Concentration (% w/w) in 1% pluronic L92 in distilled water	DPM	DPM/node	Stimulation index	Results
Vehicle	2501.00	312.63	n.a.	n.a.
1	3176.25	397.27	1.27	Negative
2.5	2938.16	367.27	1.17	Negative
5	3279.54	409.94	1.31	Negative

Interpretation of results:

GHS criteria not met

Conclusions:

The test material was considered to be a non-sensitiser under the conditions of the test. The study is considered to be reliable and acceptable for use as a key study for read across to pentapotassium triphosphate (potassium tripolyphosphate).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

A negative LLNA test is available for pentasodium triphosphate (sodium tripolyphosphate), read across is proposed from this to pentapotassium triphosphate.

Both are ionic inorganic compounds containing the same phosphate group, any sensitisation potential from the anion will be the same for both compounds.

Sodium and potassium are both group 1 alkali metals, the ionic charges are the same and the chemical behaviour will be similar. Potassium has a larger ionic radius and as penetration of the skin is largely governed by molecular size, the ability of potassium to penetrate the skin is likely to be less than sodium.

As the chemical behaviour of both the anion and the cation will be similar and the dermal absorption of the cation is likely to be reduced, the negative results from pentasodium triphosphate can reliably be read across to pentapotassium triphosphate.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The data available for the skin sensitisation can be used to infer that no classification is necessary for pentapotassium triphosphate according to regulation (EC) No. 1272/2008 (EU CLP).

There are no data (study or workplace observations) to suggest that pentapotassium triphosphate is a respiratory sensitiser.