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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification
Justification for type of information:
The supporting QMRF report has been attached
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Prediction is done using OECD QSAR Toolbox version 3.3 with logKow as the primary descriptor.
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material (IUPAC name): 3,7-bis(diethylamino)phenoxazin-5-ium acetate
- Molecular formula: C22H29N3O3
- Molecular weight: 383.489 g/mol
- Smiles notation: c1c2nc3ccc(cc3[o+]c2cc(N(CC)CC)c1)N(CC)CC.C(C)(=O)[O-]
- InChl: 1S/C20H26N3O.C2H4O2/c1-5-22(6-2)15-9-11-17-19(13-15)24-20-14-16(23(7-3)8-4)10-12-18(20)21-17;1-2(3)4/h9-14H,5-8H2,1-4H3;1H3,(H,3,4)/q+1;/p-1
- Substance type: Organic
- Physical state: Solid
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Tetrahymena pyriformis
Test type:
static
Water media type:
freshwater
Total exposure duration:
48 h
Remarks on exposure duration:
Standard duration : 2 days
Reference substance (positive control):
not specified
Key result
Duration:
48 h
Dose descriptor:
other: IGC50
Effect conc.:
51.967 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
other: Growth

The prediction was based on dataset comprised from the following descriptors: IGC50
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

(((("a" or "b" )  and ("c" and ( not "d") )  )  and "e" )  and ("f" and "g" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as SN1 AND SN1 >> Nitrenium Ion formation AND SN1 >> Nitrenium Ion formation >> Tertiary aromatic amine by DNA binding by OECD

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Peroxy Acids by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OASIS v1.3

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Michael Addition OR Michael Addition >> alpha,beta-Unsaturated carbonyl compounds OR Michael Addition >> alpha,beta-Unsaturated carbonyl compounds >> alpha,beta-Aldehydes  OR Schiff base formation OR Schiff base formation >> Schiff base formation with carbonyl compounds OR Schiff base formation >> Schiff base formation with carbonyl compounds >> Aldehydes by Protein binding by OASIS v1.3

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Class 5 (Not possible to classify according to these rules) by Acute aquatic toxicity classification by Verhaar (Modified) ONLY

Domain logical expression index: "f"

Parametric boundary:The target chemical should have a value of log Kow which is >= 2.17

Domain logical expression index: "g"

Parametric boundary:The target chemical should have a value of log Kow which is <= 5.12

Validity criteria fulfilled:
not specified
Conclusions:
The inhibitory growth concentration (IGC50) value for 3,7-bis(diethylamino)phenoxazin-5-ium acetate on Tetrahymena pyriformis in a 48 hour study was estimated to be 51.96 mg/L on the basis of effects on growth.
Executive summary:

Using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, toxicity to microorganisms was predicted for target substance 3,7-bis(diethylamino)phenoxazin-5-ium acetate (CAS no. 79916 -07 -7). IGC50 value was estimated to be 51.96 mg/l for Tetrahymena pyriformis for 48 h duration.

Description of key information

Using the OECD QSAR toolbox version 3.3 (2017) with log kow as the primary descriptor and considering the five closest read across substances, toxicity to microorganisms was predicted for target substance 3,7-bis(diethylamino)phenoxazin-5-ium acetate (CAS no. 79916 -07 -7). IGC50 value was estimated to be 51.96 mg/l for Tetrahymena pyriformis for 48 h duration.

Key value for chemical safety assessment

EC50 for microorganisms:
51.96 mg/L

Additional information

Predicted data for the target chemical 3,7-bis(diethylamino)phenoxazin-5-ium acetate (CAS No. 79916-07-7) and various supporting weight of evidence studies for its closest read across substances with logKow as the primary descriptorwere reviewed for toxicity to microorganism endpoint to summarize the following information:

 

Toxicityto microorganismof target chemical3,7-bis(diethylamino)phenoxazin-5-ium acetate(CAS No. 79916-07-7) is predicted using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances (2017).On the basis of effects observed, the IGC50 value was estimated to be 51.96 mg/l for Tetrahymena pyriformis for 48 h duration.

 

In a weight of evidencestudy from peer reviewed journal (Dr. D. Brown et. al, 1981) of the read across chemical 3',6'-bis(diethylamino)spiro[isobenzofuran-1(3H),9'-[9H]xanthene ]-3-one (CAS no. 509-34-2),a screening method based on the measurement of the respiration rate of activated sludge for assessing the possible inhibitory effect of dyestuffs on aerobic waste-water bacteria. The test principle involves measuring the respiration rate of an activated sludge and comparing it with the respiration rate of the same activated sludge under identical conditions, but in the presence of the chemical under test. The test was carried out in activated sludge respiration rate apparatus with constant 20 ± 2°C and pH about 7-8. The test concentration used was 100 mg/l. OECD recommended synthetic sewage was used as feed, while activated sludge was obtained from a sewage works treating predominantly domestic sewage or from a sewage works treating predominantly industrial waste water. The respiration rate of an activated sludge and the respiration rate of activated sludge with test chemical were noted down. In order to calculate the inhibitory effect of a particular chemical at 100 mg/l test concentration its respiration rate is expressed as a percentage of the mean of the two control respiration rates. For those chemicals whose respiration rate is at least 80% of the control, the IC50 (concentration for 50% inhibition of respiration rate) is recorded as >100 mg/l. Thus, IC50 value (concentration for 50% inhibition of respiration rate) for the test chemical 3',6'-bis(diethylamino)-3H-spiro[2 -benzofuran-1,9'-xanthen]-3 -one on activated sludge (aerobic bacteria) is determined to be >100 mg/1 after 3 hrs of exposure.

 

For the read across chemical Diethyl aniline (CAS no. 91-66-7), toxicity to micro-organism (bacteria) study was carried out for 3 hrs (HPVIS, 2017). The study was performed according to a Screening Test for the Assessment of the Possible Inhibitory Effect of a Chemical Substance on Aerobic Waste Water Bacteria method. Activated sludge was used as a test organism during the study. Based on the inhibitory effect on the test organism activated sludge, the 3 hr EC50 value was determined to be > 100 mg/l.

 

Thus, based on the overall reported results for target chemical3,7-bis(diethylamino)phenoxazin-5-ium acetate(OECD QSAR toolbox version 3.3, 2017) and for its read across substance (frompeer reviewed journal and secondary source HPVIS),it can be concluded that the IGC50 value for the test chemical3,7-bis(diethylamino)phenoxazin-5-ium acetatewas estimated to be 51.96 mg/l, respectively.