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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
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:
Data is from OECD QSAR toolbox version.3.3 and QMRF report has been attached.
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: Predicted data
Principles of method if other than guideline:
Prediction is done using QSAR Toolbox version 3.3 with log kow as the primary discriptors.
GLP compliance:
not specified
Test material information:
Composition 1
Specific details on test material used for the study:
- Name of test material (IUPAC name): trisodium 2-[(E)-2-(3-methyl-5-oxo-1-{4-[2-(sulfonatooxy)ethanesulfonyl]phenyl}-4,5-dihydro-1H-pyrazol-4-yl)diazen-1-yl]naphthalene-1,5-disulfonate
- Molecular formula: C22H17N4Na3O13S4
- Molecular weight: 742.6253 g/mol
-InChl:1S/C22H20N4O13S4.3Na/c1-13-20(22(27)26(25-13)14-5-7-15(8-6-14)40(28,29)12-11-39-43(36,37)38)24-23-18-10-9-16-17(21(18)42(33,34)35)3-2-4-19(16)41(30,31)32;;;/h2-10,20H,11-12H2,1H3,(H,30,31,32)(H,33,34,35)(H,36,37,38);;;/q;3*+1/p-3/b24-23+;;;
- Substance type: Organic
- Physical State: Solid
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
169.602 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: no toxic

The prediction was based on dataset comprised from the following descriptors: EC50
Estimation method: Takes average value from the 7 nearest neighbours
Domain  logical expression:Result: In Domain

(((((((("a" or "b" or "c" or "d" or "e" )  and ("f" and ( not "g") )  )  and "h" )  and ("i" and ( not "j") )  )  and ("k" and ( not "l") )  )  and "m" )  and ("n" and ( not "o") )  )  and ("p" and "q" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Naphthalene sulfonic acids, condensates by OECD HPV Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Vinyl Sulfones by US-EPA New Chemical Categories

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as SN1 OR SN1 >> Nitrenium Ion formation OR SN1 >> Nitrenium Ion formation >> Aromatic azo OR SN1 >> Nitrenium Ion formation >> Unsaturated heterocyclic azo by DNA binding by OECD ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Schiff base formation OR Schiff base formation >> Pyrazolones and Pyrazolidinones derivatives OR Schiff base formation >> Pyrazolones and Pyrazolidinones derivatives >> Pyrazolones and Pyrazolidinones  by Protein binding by OASIS v1.3 ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Direct Acylation Involving a Leaving group OR Acylation >> Direct Acylation Involving a Leaving group >> Acetates OR SN2 OR SN2 >> SN2 reaction at sp3 carbon atom OR SN2 >> SN2 reaction at sp3 carbon atom >> Alkyl diazo by Protein binding by OECD ONLY

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OASIS v.1.3

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >> Michael-type addition on alpha, beta-unsaturated carbonyl compounds OR AN2 >> Michael-type addition on alpha, beta-unsaturated carbonyl compounds >> Four- and Five-Membered Lactones OR AN2 >> Shiff base formation after aldehyde release OR AN2 >> Shiff base formation after aldehyde release >> Specific Acetate Esters OR Non-covalent interaction OR Non-covalent interaction >> DNA intercalation OR Non-covalent interaction >> DNA intercalation >> DNA Intercalators with Carboxamide Side Chain OR SN1 OR SN1 >> Nucleophilic attack after carbenium ion formation OR SN1 >> Nucleophilic attack after carbenium ion formation >> Specific Acetate Esters OR SN2 OR SN2 >> Acylation OR SN2 >> Acylation >> Specific Acetate Esters OR SN2 >> Alkylation, ring opening SN2 reaction OR SN2 >> Alkylation, ring opening SN2 reaction >> Four- and Five-Membered Lactones OR SN2 >> Nucleophilic substitution at sp3 Carbon atom OR SN2 >> Nucleophilic substitution at sp3 Carbon atom >> Specific Acetate Esters by DNA binding by OASIS v.1.3

Domain logical expression index: "h"

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: "i"

Referential boundary: The target chemical should be classified as Acid moiety AND Amides AND Hydrazines AND Salt by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Acrylamides OR Aliphatic Amines by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Acid moiety AND Amides AND Hydrazines AND Salt by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "l"

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

Domain logical expression index: "m"

Similarity boundary:Target: CC1C(N=Nc2ccc3c(S(=O)(=O)O{-}.[Na]{+})cccc3c2S(=O)(=O)O{-}.[Na]{+})C(=O)N(c2ccc(S(=O)(=O)CCOS(=O)(=O)O{-}.[Na]{+})cc2)N=1
Threshold=20%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Alkali Earth AND Non-Metals by Groups of elements

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Halogens by Groups of elements

Domain logical expression index: "p"

Parametric boundary:The target chemical should have a value of log Kow which is >= -3.32

Domain logical expression index: "q"

Parametric boundary:The target chemical should have a value of log Kow which is <= 3.7

Conclusions:
Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic algae was predicted trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9). EC50 intoxication value was estimated to be 169.602 mg/l for Desmodesmus subspicatus for 72 hrs duration. It was concluded that trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9) was likely to be not toxic to aquatic algae.
Executive summary:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic algae was predicted trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9). EC50 intoxication value was estimated to be 169.602 mg/l for Desmodesmus subspicatus for 72 hrs duration. It was concluded that trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9) was likely to be not toxic to aquatic algae.

Description of key information

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic algae was predicted trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9). EC50 intoxication value was estimated to be 169.602 mg/l for Desmodesmus subspicatus for 72 hrs duration. It was concluded that trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9) was likely to be not toxic to aquatic algae.

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
169.602 mg/L

Additional information

Following three studies of target chemical and structurally similar read across includes predicted data and experimental data to conclude the toxicity extent of trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9) towards aquatic algae is summarized as follows:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic algae was predicted trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9). EC50 intoxication value was estimated to be 169.602 mg/l for Desmodesmus subspicatus for 72 hrs duration. It was concluded that trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9) was likely to be not toxic to aquatic algae.

The above predicted data of target chemical is supported by the experimental study of structurally similar read across

disodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonatE(CAS: 2783 -94 -0) from the ABITEC Lab report 2016, suggests that the

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substancedisodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonateaccording to OECD Guideline 201.

The test substance was dissolved in DMSO and tested at the concentrations 0, 17, 30, 55, 100 and 185 mg/L. Effects on the growth rate of the organism were studied.

The median effective concentration (EC50) for the test substance,disodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate, in Desmodesmus subspicatus was determined to be 113.2 mg/L.

This value indicates that the substance is not likely to be hazardous to aquatic algae as per the CLP criteria.

Another supporting experimental study for the structurally similar read across ε-caprolactam (CAS: 105-60-2) from the publication Chemosphere 1997, also suggests that the Short term toxicity to aquatic invertebrate test was carried for ε-caprolactam to study the effects on aquatic invertebrate. decreasing trend ogf Population (Abundance) was measured during the test.

Effective concentration to 50% of Pseudokirchneriella subcapitata when exposed to ε-caprolactam for 72 h is 4550 mg/L. It can be concluded from the Population (Abundance) value that the  ε-caprolactam is not toxic to the aquatic algae and can be considered as “not classified” as per the classification criteria for aquatic environment.

Thus based on the effect concentrations which is in the range 113.2 mg/l to 4550 mg/l give the conclusion that test substance trisodium 2-{[3-methyl-5-oxo-1-(4-{[2-(sulfonatooxy)ethyl]sulfonyl}phenyl)-4,5-dihydro-1H-pyrazol-4-...(CAS: 20298-05-9) was likely to be not toxic to aquatic algae at environmentally relevant concentrations and can be considered to be “not classified” as per the CLP classification criteria.