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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
16 May 2012 - 19 June 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP-study, no deviation.
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read across follows Scenario 5 - Qualitatively and quantitatively similar effects are caused by a common compound, which is formed from all category members (as described in the 2017 Read-Across Assessment Framework document).
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
TARGET: Reaction Mass of 4-sulphophthalic acid and 3-sulphophthalic acid (ratio 3:1)
SOURCE: Sulphophthalic acid sodium salts
3. CATEGORY APPROACH JUSTIFICATION
Sulphophthalic acid sodium and ammonium salts are different organic salts of a common acid, sulfophthalic acid. The salts dissociate rapidly in the medium (water) to the common sulphophthalic acid anion and to their different counter ions. The counter ions ammonium and sodium do not influence the solubility and the toxicity of the category members.
4. DATA MATRIX
See Read Across document attached to CSR.
Qualifier:
according to
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Municipal activated sludge from laboratory wastewater treatment plant fed with municipal sewage and synthetic wastewater.
- Concentration of sludge: 30 mg/l
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
DOC
Remarks:
equivalent to 199 mg/L
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
aniline
Key result
Parameter:
% degradation (DOC removal)
Remarks:
Test Temperature: 22± 2°C
Value:
> 90 - < 100
Sampling time:
28 d
Results with reference substance:
- Deviation of degree of biodegradation of the test substance at the end of exposure should be <20%: Yes
- Degree of biodegradation of the reference substance should be >70% DOC after 14 days: Yes (97%)
- Degree of biodegradation in the inhibition control should be >35 % DOC after 14 days: Yes (70%)
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Executive summary:

There are no biodegradation studies on the 4-sulphophthalic acid and 3-sulphophthalic acid reaction mass (read across target substance) and biodegradation information from a dissolved organic carbon (DOC) Die-Away test on the reaction mass of 1,2-Benzenedicarboxylic acid, 4-sulfo-, trisodium salt, 1,2-Benzenedicarboxylic acid, 3-sulfo-, sodium salt (1:3), sodium sulphate (read across source substance) was used for reading across. The DOC values at the respective sampling days were compared to the DOC values determined on day 0 at begin of exposure. At the end of exposure after 28-days the degree of biodegradation was 90-100 % expressed as removal of DOC. The degree of biodegradation was calculated as mean of the values from two test assays at the end of exposure. The sulphophthalic acid sodium salt reaction mass was 90 -100% biodegradable in the DOC Die-Away Test. Based on the determined rate of biodegradation at the end of exposure the read across source substance can be evaluated as readily biodegradable.

Description of key information

There are no biodegradation studies on the 4-sulphophthalic acid and 3-sulphophthalic acid reaction mass (read across target substance) and biodegradation information from a dissolved organic carbon (DOC) Die-Away test on the reaction mass of 1,2-Benzenedicarboxylic acid, 4-sulfo-, trisodium salt, 1,2-Benzenedicarboxylic acid, 3-sulfo-, sodium salt (1:3), sodium sulphate (read across source substance) was used for reading across purposes. The DOC values at the respective sampling days were compared to the DOC values determined on day 0 at begin of exposure. At the end of exposure after 28-days the degree of biodegradation was 90-100 % expressed as removal of DOC. The degree of biodegradation was calculated as mean of the values from two test assays at the end of exposure. The sulphophthalic acid sodium salt reaction mass was 90 -100% biodegradable in the DOC Die-Away Test. Based on the determined rate of biodegradation at the end of exposure the read across source substance can be evaluated as readily biodegradable. Consequently, the read across target substance is consider readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information