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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 the QMRF report has been attached.
Qualifier:
according to guideline
Guideline:
other: Estimated data
Version / remarks:
No data available
Deviations:
not specified
Principles of method if other than guideline:
Prediction was done using the OECD QSAR toolbox version 3.3.
GLP compliance:
not specified
Specific details on test material used for the study:
Name of test material : 2-hydroxy-p-toluic acid (m cresotic acid)
Molecular formula :C8H8O3
Molecular weight :152.148 g/mol
Smiles notation :Cc1ccc(c(c1)O)C(=O)O
InChl :1S/C8H8O3/c1-5-2-3-6(8(10)11)7(9)4-5/h2-4,9H,1H3,(H,10,11)
Substance Type: Organic
Physical State: Solid
Analytical monitoring:
not specified
Details on sampling:
No data available
Vehicle:
not specified
Details on test solutions:
No data available
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
No data available
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Remarks on exposure duration:
No data available
Post exposure observation period:
No data available
Hardness:
No data available
Test temperature:
No data available
pH:
8.2
Dissolved oxygen:
No data available
Salinity:
No data available
Conductivity:
No data available
Nominal and measured concentrations:
nominal
Details on test conditions:
No data available
Reference substance (positive control):
not specified
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
112.815 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: from QSAR
Details on results:
No data available
Results with reference substance (positive control):
No data available
Reported statistics and error estimates:
No data available

The prediction was based on dataset comprised from the following descriptors: EC50
Estimation method: Takes average value from the 6 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 ( not "i") )  )  and "j" )  and ("k" and ( not "l") )  )  and ("m" and ( not "n") )  )  and ("o" and ( not "p") )  )  and ("q" and "r" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as m,p - Cresols by OECD HPV Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Phenols (Acute toxicity) by US-EPA New Chemical Categories

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Weak binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Class 2 (less inert compounds) by Acute aquatic toxicity classification by Verhaar (Modified)

Domain logical expression index: "e"

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

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OECD

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Michael addition OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Alkyl phenols OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Arenes OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Hydroquinones OR SN1 OR SN1 >> Iminium Ion Formation OR SN1 >> Iminium Ion Formation >> Aliphatic tertiary amines OR SN1 >> Nitrenium Ion formation OR SN1 >> Nitrenium Ion formation >> Aromatic azo OR SN1 >> Nitrenium Ion formation >> Aromatic nitro OR SN1 >> Nitrenium Ion formation >> Primary aromatic amine OR SN1 >> Nitrenium Ion formation >> Tertiary aromatic amine by DNA binding by OECD

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OECD

Domain logical expression index: "i"

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 SNAr OR SNAr >> Nucleophilic aromatic substitution OR SNAr >> Nucleophilic aromatic substitution >> Halo-triazines by Protein binding by OECD

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Bioavailable by Lipinski Rule Oasis ONLY

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as No alert found by Carcinogenicity (genotox and nongenotox) alerts by ISS

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as o-phenylphenol (Nongenotox) OR Phtalate (or buthyl) diesters and monoesters (Nongenotox) OR Structural alert for nongenotoxic carcinogenicity by Carcinogenicity (genotox and nongenotox) alerts by ISS

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Known precedent reproductive and developmental toxic potential AND Toluene and small alkyl toluene derivatives (8a) by DART scheme v.1.0

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Not known precedent reproductive and developmental toxic potential by DART scheme v.1.0

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Group 14 - Carbon C AND Group 16 - Oxygen O by Chemical elements

Domain logical expression index: "p"

Referential boundary: The target chemical should be classified as Group 16 - Sulfur S by Chemical elements

Domain logical expression index: "q"

Parametric boundary:The target chemical should have a value of log Kow which is >= 1.64

Domain logical expression index: "r"

Parametric boundary:The target chemical should have a value of log Kow which is <= 3.42

Validity criteria fulfilled:
not specified
Conclusions:
The EC50 value was estimated to be 112.814 mg/l when 2-hydroxy-p-toluic acid (m cresotic acid) exposed to Desmodesmus subspicatus for 72 hrs
Executive summary:

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, toxicity on Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)was predicted for2-hydroxy-p-toluic acid (m cresotic acid) (50-85-1).The EC50 value was estimated to be 112.814 mg/l when 2-hydroxy-p-toluic acid (m cresotic acid) exposed to Desmodesmus subspicatus for 72 hrs.

Description of key information

Toxicity to aquatic algae and cynobacteria:

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, toxicity on Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)was predicted for2-hydroxy-p-toluic acid (m cresotic acid) (50-85-1).The EC50 value was estimated to be 112.814 mg/l when 2-hydroxy-p-toluic acid (m cresotic acid)exposed toDesmodesmus subspicatus for 72 hrs.

Key value for chemical safety assessment

EC50 for freshwater algae:
112.814 mg/L

Additional information

Toxicity to aquatic algae and cynobacteria:

Based on the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, toxicity on Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)was predicted for 2-hydroxy-p-toluic acid (m cresotic acid) (50-85-1).The EC50 value was estimated to be 112.814 mg/l when 2-hydroxy-p-toluic acid (m cresotic acid)exposed toDesmodesmus subspicatus for 72 hrs.

The above prediction was supported another prediction for the target .Based on the prediction done using thethree different models i.e, Battery, Leadscope and SciQSAR used within Danish QSAR database, the short term toxicity on green algae was predicted for test substance m cresotic acid (2 -hydroxy-p-toluic acid) for cas 50 -85 -1. The average EC50 value was given by the third model i.e, Battery model. On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance m cresotic acid is estimated to be 159.23 mg/l for Pseudokirchneriella subcapitata during 72 hr exposure duration. Thus, on the basis of EC50 value,it can be concluded that the test chemical m cresotic acid can be considered as non toxic to green algae at environmentally relevant concentrations and can be considered not classified as per the CLP classification criteria.

The above predictions were further supported by summarized in Japan chemicals collaborative knowledge database (J-check), 2016 for structurally similar read across substance 4-Hydroxybenzoic acid (CAS: 99 -96 -7).

Short term toxicity toalgaestudy was carried out for 72 hrs. The study was performed according toOECD guideline 201 (Algal, Growth Inhibition Test).The study was based on the effects of the test compound onalgaein a static fresh water system.Based on effect on growth rate ofalgae,the 72 hr EC50 and NOEC value was determined to be 110 and 51 mg/l, respectively, and on the basis of AUG, the 72 hr EC50 and NOEC value was determined to be 69 and 32 mg/l, respectively.Thus, based onEC50value (110 mg/l), it can be concluded that the substance4-Hydroxybenzoic acidcan be considered as non-toxic to aquatic organisms and thus cannot be classifiedas hazardous, as per the CLP criteria.

The above experimental data was further supported by Ecotox database, U.S Environmental Protection Agency,2017 for structurally similar read across substance Salicylic acid (CAS: 69 -72 -7).

Short term toxicity study to Haematococcus pluvialis by using chemical salicylic acid was carried out, by using static method. Based on the growth inhibition of population of Haematococcus pluvialis, EC10 was 165 mg/l.Hence chemical salicylic acid was consider non toxic and can be concluded as not classified as per the CLP classification criteria.

Another experimental study for the structurally similar read across substance Benzoic acid (CAS: 65 -85 -0) was sumarized inECOTOX database, U. S. Environmental Protection Agency, 2016

Short term toxicity toPseudokirchneriella subcapitata(green algae) study was carried out for 48 hrs.The study was based on the effects of the test compound Benzoic acid (CAS: 65 -85 -0) onPseudokirchneriella subcapitatain a static fresh water system. On the basis of population of the test organismPseudokirchneriella subcapitata(green algae), the 48 hr EC50 value was determined to be 207.5 mg/l.

Thus, based on this values of target as well as structurally similar read across substance , it can be concluded that the substance 2-hydroxy-p-toluic acid (m cresotic acid) (50-85 -1) can be considered as non-toxic to aquatic organisms and thus cannot be classified as hazardous as per the CLP criteria.