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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.
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
Specific details on test material used for the study:
- Name of the test material: α-bromo-m-toluonitrile
- IUPAC name: 3-(bromomethyl)benzonitrile
- Molecular formula: C8H6BrN
- Molecular weight: 196.046 g/mol
- Smiles: N#Cc1cc(CBr)ccc1
- Inchi: 1S/C8H6BrN/c9-5-7-2-1-3-8(4-7)6-10/h1-4H,5H2
- Substance type: Organic
- Physical state : Solid crystalline powder (Off white)
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
217.95 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
other: Growth
Remarks on result:
other: not toxic

The prediction was based on dataset comprised from the following descriptors: EC50
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

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

Domain logical expression index: "a"

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

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as SN2 OR SN2 >> SN2 reaction at sp3 carbon atom OR SN2 >> SN2 reaction at sp3 carbon atom >> Alkyl halides OR SN2 >> SN2 reaction at sp3 carbon atom >> alpha-Halobenzyls (and related cyano, sulfate and sulphonate subs. chem.) by Protein binding by OECD ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as SN2 OR SN2 >> Nucleophilic substitution at sp3 carbon atom OR SN2 >> Nucleophilic substitution at sp3 carbon atom >> Alkyl halides  OR SN2 >> Nucleophilic substitution on benzilyc carbon atom OR SN2 >> Nucleophilic substitution on benzilyc carbon atom >> alpha-Activated benzyls  by Protein binding by OASIS v1.3 ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as SN2 OR SN2 >> SN2 at an sp3 Carbon atom OR SN2 >> SN2 at an sp3 Carbon atom >> Aliphatic halides by DNA binding by OECD ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >> Shiff base formation for aldehydes OR AN2 >> Shiff base formation for aldehydes >> Haloalkane Derivatives with Labile Halogen OR SN2 OR SN2 >> Acylation involving a leaving group  OR SN2 >> Acylation involving a leaving group  >> Haloalkane Derivatives with Labile Halogen OR SN2 >> Alkylation, nucleophilic substitution at sp3-carbon atom OR SN2 >> Alkylation, nucleophilic substitution at sp3-carbon atom >> Haloalkane Derivatives with Labile Halogen by DNA binding by OASIS v.1.3 ONLY

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as SN2 AND SN2 >> SN2 at an sp3 Carbon atom AND SN2 >> SN2 at an sp3 Carbon atom >> Aliphatic halides by DNA binding by OECD ONLY

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Alkyl halide AND Aryl AND Benzyl AND Nitrile by Organic Functional groups

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Aryl halide by Organic Functional groups

Domain logical expression index: "i"

Parametric boundary:The target chemical should have a value of log Kow which is >= 0.778

Domain logical expression index: "j"

Parametric boundary:The target chemical should have a value of log Kow which is <= 2.5

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 algae was predicted 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) EC50 intoxication value was estimated to be 217.95 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) was likely to be not toxic to 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 algae was predicted 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) EC50 intoxication value was estimated to be 217.95 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) was likely to be not toxic to 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 algae was predicted 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) EC50 intoxication value was estimated to be 217.95 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) was likely to be not toxic to algae.

Key value for chemical safety assessment

EC50 for freshwater algae:
217.95 mg/L

Additional information

Following studies include the predicted data and experimental study for the target chemical and structurally similar read across to conclude the toxicity extent of 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) towards 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 algae was predicted 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) EC50 intoxication value was estimated to be 217.95 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that 3-(bromomethyl)benzonitrile (CAS: 28188-41-2) was likely to be not toxic to algae.

The predicted data for the target chemical is supported by the experimental study of structurally similar read aross 1,2-dichloropropane (CAS: 78 -87 -5) from the publication Chemosphere 1994, suggests that the Toxicity to aquatic algae and cyanobacteria test was carried out for 1,2-dichloropropane to study the effects on aquatic algae. The decrease in Population changes was recorded during the test.

The Effective concentration to 50% of Scenedesmus subspicatus in 72 hr is 168 mg/L. It can be concluded from the value that the 1,2-dichloropropane is not toxic to the aquatic algae and can be considered as “not classified” as per the classification criteria for aquatic environment.

Another experimental data of read across chemical 1,1,2-trichloroethane (CAS: 79 -00 -5) from the publication Chemosphere 1994, suggests that the

Toxicity to aquatic algae and cyanobacteria test was carried out for 1,1,2-richloroethane to study the effects on aquatic algae. Decreasing trend of Population changes, were measured during the test.

The Effective concentration EC50 to 50% of Scenedesmus subspicatus in 72 hr for 1,1,2-trichloroethane is 200 mg/L. It can be concluded from the value that the 1,1,2-trichloroethane is not toxic to the aquatic algae and can be considered as “not classified” as per the classification for aquatic environment.

Thus based on the effect concentrations which is in the range 168 mg/L to217.95 mg/lgive the conclusion that test substance3-(bromomethyl)benzonitrile (CAS: 28188-41-2)is likely to be not toxic to aquatic algae at environmentally relevant concentrations and applying weight of evidence approach it can be considered to be “not classified” as per the CLP classification criteria.