Pentapotassium triphosphate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

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. Both substances will ultimately dissociate into the common breakdown products of the Na+ or K+ cations and the P3O105- anion, resulting in further breakdown products of pyrophosphate and orthophosphate anions.
3. Sodium and potassium cations are ubiquitous in natural waters and are considered to possess similar toxicological and ecotoxicological profiles due in part to their similar behaviour and their existence as essential micronutrients. The triphosphate anion in both substances will breakdown in the environment via the processes of hydrolysis, biotic degradation and assimilation by organisms in the environment, resulting in the breakdown products of pyrophosphate and orthophosphate anions. Ultimately, pyrophosphate anions will also breakdown to orthophosphate. It is therefore considered to be scientifically unjustified to conduct further testing on pentapotassium triphosphate as the read across can be adequately justified.


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:

other: French standard NF T90-303 (AFNOR 1985a)

Deviations:

no

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

A stock solution of the substance at a concentration of 100 g/L was initially prepared in bi-distilled water.
Dilutions of this initial solution were then performed with reconstitued river water, normalised at pH 8.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Test type:

other: According to guideline AFNOR T 90 303

Water media type:

freshwater

Limit test:

no

Total exposure duration:

24 h

Post exposure observation period:

No data.

Hardness:

No data.

Test temperature:

No data.

pH:

pH 8.00

Dissolved oxygen:

No data.

Salinity:

No data.

Nominal and measured concentrations:

No data.

Details on test conditions:

No data.

Reference substance (positive control):

yes

Remarks:

sodium nitrilotriacetate

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

1 850 mg/L

Nominal / measured:

nominal

Basis for effect:

mortality (fish)

Details on results:

The LC50 (to danio rerio (zebra fish)) after 24h was >1800 mg/L.

Results with reference substance (positive control):

Toxicity of sodium nitrilotriacetate: CL(I) 40.24H = ca. 900 mg/l
Sodium nitriloacetate was approximately twice as toxic than the test material.

Reported statistics and error estimates:

No data.

Sublethal observations / clinical signs:

Table 1 - Results

Test Material Concentration (mg/l)	pH Solution	Percentage of Mortality (at 24h)
2000	10.0	100
1800	9.8	40
1600	9.7	0
1400	9.5	0
1200	9.3	0
0	7.4	0

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test item to the freshwater zebrafish (Danio rerio) has been investigated and gave a 24-Hour LC50 of greater than 1800 mg/L.

Description of key information

Four studies are available for the short-term toxicity to fish. The tests were performed using analogous substance pentasodium triphosphate which is considered suitable in the assessment of pentapotassium triphosphate for the reasons stipulated in the discussion below.
- The study conducted by Dion M (1985) is considered the key study as, although it has not been conducted to OECD guidelines, it is well documented and in accordance with national standard methods (AFNOR T 90 303). Results from this study must be treated with some caution as testing was only performed for 24h. The acute fish toxicity of the test material was 1850 mg/L.
- The second study (Kastner W, 1983) only provided a value of CL0 (highest tested concentration without effects).
- The remaining studies provide additional support for the conclusion that the test material is not considered to be classified according to Regulation (EC) No 1272/2008. 
In section 6.1.2 of this dossier a study performed following similar methods to OECD guideline 212 (short term toxicity test on embryo and sac-fry) has also been submitted (LOEC = 5 mg/L).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 850 mg/L

Additional information

Read across from pentasodium triphosphate to pentapotassium triphosphate is justified on the following basis:

Both substances are inorganic compounds containing a triphosphate anion and a group 1 alkali metal cation. Both sodium and potassium cations are ubiquitous in natural waters and are considered to possess similar toxicological and ecotoxicological profiles due in part to their similar behaviour and their existence as essential micronutrients. The triphosphate anion in both substances will breakdown in the environment via the processes of hydrolysis, biotic degradation and assimilation by organisms in the environment, resulting in the breakdown products of pyrophosphate and orthophosphate anions. Ultimately, pyrophosphate anions will also breakdown to orthophosphate.

It is therefore considered to be scientifically unjustified to conduct further testing on pentapotassium triphosphate as the read across can be adequately justified.