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Additional information

Aquatic toxicity data has been compiled for analogue substances which are expected to behave and exert effects in solution in an identical or very similar way to potassium dosium tartrate. Abundant reliable data, and as key srudies for this assessment, has been derived from aquatic toxicity tests performed by the Japanese Ministry of the environment on disodium succinate, a C4 dibasic carboxyllic acid salt which is structurally very similar to sodium potassium tartrate. Data from aquatic toxicity tests on other closely related C4 dicarboxyllic acids such as fumaric and malic acid has also been provided, in the absence of reliable data with similar tartaric acid salts. In addition microbial toxicity data has been derived from 14d biodegradation studies performed on a solution of disodium tartrate.

Predictions obtained using a QSAR model (MultiCASE) for estimating the acute toxicity of Potassium Sodium Tartrate in Fat-head minnow (fish), Selenastrum capricornutum (algae) and Daphnia magna, yield results which are comparable to those obtained experimentally with the analogue substances indicated below, improving confidence in the values employed in the derivation of the PNEC values proposed.

A summary of read across data considered in this dataset follows (same table with structural images included as attachment):

 

 

Fish

Invertebrates

Algae

Sodium Potassium Tartrate

C4H4O6NaK

 

No data available

 

No data available

 

No data available

 

 

Disodium succinate

C4H4O4Na2

 

Oryzias latipes

 

96h LC50> 95.4 mg/L

96h LC047.0 mg/L

 

Daphnia magna

 

48 h LC50= > 997 mg/L

48h NOEC = 997 mg/L

 

21 d – LC0= >95.2 mg/L

21 d EC50repro = >95.2 mg/L

21d NOEC = 95.2 mg/L

 

Selenastrum capricornutum

 

72h ErC50= > 998 mg/L

72h NOEC = 998 mg/L

 

 

 

 

Tartaric acidC4H6O6

 

 

 

Chlorococcum littorale

 

EC50 > 600 mg/L

EC10 = 600 mg/L (approx)

 

 

 

 

 

Malic acid – C4H6O5

 

 

Daphnia magna

 

48 h LC50= 240 mg/L

48h NOEC = 100 mg/L

 

 

 

 

Fumaric acid - C4H4O4

 

Danio rerio (Zebra fish)

 

LC50 48 h = 245 mg/L

 

 

 

Scenedesmus subspicatus

 

ErC50 = 41 mg/L

EC10 = 31 mg/L

 

 

 

 

  

 

Microorganisms

Disodium tartrate

C4H4O6Na2

 

OECD14d biodegradation test indicated no toxicity ti innoculum at concentrations tested.

 

NOEC sludge > 100 mg/L (anhydrate)

 

 

 

 

The relevance of other C4 and related dicarboxylic acids for read-across to the PNaTartrate is also supported by the comparison of available physical-chemical data:

Properties of related aliphatic carboxyllic acids and its salts
Name Formula CAS Mol.wt Boil. P (°C) Melt. P (°C) Water. Sol (g/L) ca. 25 Vap. Press. (hPa) Log Kow     (25 °) pKa 
Tartaric acid C4H6O6 526-83-0 150,1 171   very sol     3,03; 4,37
Succinic acid C4H6O4 110-15-6 118,1 189 235 (dec) slightly sol     4,21; 5,64
Disodium succinate C4H4O4Na2 150-90-3 162 > 400 > 400 very sol > 100  < 0,00015 at 100 °C < -0,59 est  
Malic acid C4H6O5 6915-15-7 134,1 131 140 592 g/L v. Soluble 0,0000039 at 25 ° -1,26 3,40; 5,05
Fumaric acid (insat) C4H4O4 110-17-8 116,07 287 290 7 g / L soluble 0,0002 at 25° 0,33 3,02 ; 4,46
Glutaric acid C5H8O4 110-94-1 132,12 98 302 160 g/L 0.0000038 at 25° -0,29 est 4,32; 5,42
Adipic acid C6H10O4 124-04-9 146,14 153 338 23 g/L soluble 0,097 at 18,5°C 0,093 4,34; 5,44

According to the available data the following PNEC values can be calculated:

PNEC freshwater = 1.85 mg/L

Rationale: An AF of 50 is applied to the lowest NOEC value (92.5 mg/L) obtained in two taxonomic groups. In this case this corresponds to a GLP compliant 21d daphnid reproduction test. Although there is no long-term test available in fish and the available long-term values are not obtained in fish, the available data on LC50 in medaka do not support that this is the most sensitive taxonomic group, it only reflects that no effect was seen at the highest concentration tested. The LC50 for fumaric acid supports the low toxicity of the group, but is not used in the calculation as its acidity at high concentrations in contrast with Na or K salts is likely to overestimate toxicity.

PNEC freshwater (intermittent release) = 10 mg/L

Rationale: An AF of 100 is applied to the lowest reliable LC50 value available for a C4 carboxyllic acid salt (>997 mg/L).

LC50 of malic and fumaric acid indicate low toxicity of the group as a whole but have not been used as they are likely to overestimate toxicity due to the higher acidity of the test solutions.

PNEC marine = 0.185 mg/L

Rationale: Given the limited availability of reliable marine data, the PNEC would have to be derived from the lowest of 2 freshwater NOEC values, as in the previous case. An additional safety factor of 10 is introduced to take account of greater diversity in marine taxons, thereby leadin to applying an AF of 500 upon the Daphnid NOEC of 92.5 mg/L. The suitability and usefulness of this PNEC is questionable given the very rapid degradability of the carboxyllic acid and the low likelihood of its entry into the marine environment after passing a sewage treatment plant.

PNEC STP = 10 mg/L

Rationale:An AF of 10 is applied to the lowest concentration which is known to have no effect on the innoculum in a rapid biodegradability test (92.5 mg/L). In this case this is 100 mg/L of analogue disodium tartrate in an OECD 301C 14d biodegradation test performed under GLP by the Japanese MoE (2001).