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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:
QMRF report has been attached
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
Prediction was done using the OECD QSAR toolbox version 3.4
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material (IUPAC name): 3,3-Dimethyl-8,9-dinorbornan-2-one
- Common name: 1,3,3-trimethylbicyclo[2.2.1]heptan-2-one
- Molecular formula: C10H16O
- Molecular weight: 152.2354 g/mol
- Smiles notation: C[C@@]12CC[C@@H](C1)C(C)(C)C2=O
- InChl: 1S/C10H16O/c1-9(2)7-4-5-10(3,6-7)8(9)11/h7H,4-6H2,1-3H3/t7-,10+/m0/s1
- Substance type: Organic
- Physical state: Liquid
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
Total exposure duration:
72 h
Hardness:
24 mg/L as CaCO3
Test temperature:
23 to 24°C
pH:
7.9 to 8.3
Reference substance (positive control):
not specified
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
132.694 mg/L
Nominal / measured:
estimated
Conc. based on:
not specified
Basis for effect:
growth rate
Remarks on result:
other: Other details not known

The prediction was based on dataset comprised from the following descriptors: EC50
Estimation method: Takes average value from the 8 nearest neighbours
Domain  logical expression:Result: In Domain

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

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Carbonyl compound OR Ketone by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Aliphatic Carbon [CH] OR Aliphatic Carbon [-CH2-] OR Aliphatic Carbon [-CH3] OR Carbonyl, aliphatic attach [-C(=O)-] OR Miscellaneous sulfide (=S) or oxide (=O) OR Olefinic carbon [=CH- or =C<] OR Tertiary Carbon by Organic functional groups (US EPA) ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Cycloketone OR Overlapping groups OR Terpenes by Organic Functional groups (nested) ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Alkane, branched with tertiary carbon OR Bicycloheptane  OR Bridged-ring carbocycles OR Cycloalkane OR Cycloketone OR Terpenes by Organic Functional groups ONLY

Domain logical expression index: "e"

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

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Michael addition OR Michael addition >> Polarised Alkenes-Michael addition OR Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated ketones by DNA binding by OECD

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OASIS v1.4

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >> Michael addition to activated double bonds OR AN2 >> Michael addition to activated double bonds >> alpha,beta-Unsaturated Carbonyls and Related Compounds OR Nucleophilic addition OR Nucleophilic addition >> Addition to carbon-hetero double bonds OR Nucleophilic addition >> Addition to carbon-hetero double bonds >> Ketones OR Schiff base formation OR Schiff base formation >> Direct acting Schiff base formers OR Schiff base formation >> Direct acting Schiff base formers >> 1,2-Dicarbonyls and 1,3-Dicarbonyls  by Protein binding by OASIS v1.4

Domain logical expression index: "i"

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

Domain logical expression index: "j"

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

Domain logical expression index: "k"

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

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Thiols and Mercaptans OR Vinyl/Allyl Ethers by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Carbon with 4 single bonds & no hydrogens AND -CH -  [cyclic] AND -CH2-  [cyclic] AND Ketone   [-C-C(=O)-C-] AND Methyl  [-CH3] AND Number of fused acyclic rings by Bioaccumulation - metabolism alerts

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as -C=CH  [alkenyl hydrogen] by Bioaccumulation - metabolism alerts

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Moderate by Bioaccumulation - metabolism half-lives ONLY

Domain logical expression index: "p"

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

Domain logical expression index: "q"

Referential boundary: The target chemical should be classified as Metals, oxidative stress (Nongenotox) OR Structural alert for nongenotoxic carcinogenicity OR Substituted n-alkylcarboxylic acids (Nongenotox) by Carcinogenicity (genotox and nongenotox) alerts by ISS

Domain logical expression index: "r"

Referential boundary: The target chemical should be classified as Alkane, branched with tertiary carbon AND Bicycloheptane  AND Bridged-ring carbocycles AND Cycloalkane AND Cycloketone AND Terpenes by Organic Functional groups ONLY

Domain logical expression index: "s"

Referential boundary: The target chemical should be classified as Carbonyl compound AND Ketone by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "t"

Referential boundary: The target chemical should be classified as Carbonyl compound AND Ketone by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "u"

Parametric boundary:The target chemical should have a value of log Kow which is >= 1.93

Domain logical expression index: "v"

Parametric boundary:The target chemical should have a value of log Kow which is <= 3.66

Validity criteria fulfilled:
not specified
Conclusions:
Based on the growth rate inhibition of algae, the EC50 value was estimated to be132.69 mg/l when 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) exposed to Pseudokirchneriella subcapitatafor 72hrs.
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 eight closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5). Based on the growth rate inhibition of algae, the EC50 value was estimated to be132.69 mg/l when 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) exposed to Pseudokirchneriella subcapitatafor 72hrs. Based on this value it can be concluded that the substance 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) is considered be nontoxic to aquatic environment and cannot be classified as per the criteria mentioned in CLP regulation.    

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 eight closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5). Based on the growth rate inhibition of algae, the EC50 value was estimated to be132.69 mg/l when 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) exposed to Pseudokirchneriella subcapitatafor 72hrs. Based on this value it can be concluded that the substance 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) is considered be nontoxic to aquatic environment and cannot be classified as per the criteria mentioned in CLP regulation.    

Key value for chemical safety assessment

EC50 for freshwater algae:
132.6 mg/L

Additional information

Based on the various predicted data for the target chemical and experimental data for structurally and functionally similar read across chemicals study have been reviewed to determine the toxic nature of target chemical 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) on the growth of aquatic algae. The studies are as mentioned below:   

 

In the first prediction for the target chemical 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the eight closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5). Based on the growth rate inhibition of algae, the EC50 value was estimated to be132.69 mg/l when 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) exposed to Pseudokirchneriella subcapitata for 72hrs. Based on this value it can be concluded that the substance 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) is considered be nontoxic to aquatic environment and cannot be classified as per the criteria mentioned in CLP regulation.    

 

First predicted study was supported by the second experimental weight of evidence study for the read across chemical (1074-95-9) from lab report 2017. Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance (±)-menthone according to OECD Guideline 201. The stock solution (150 mg/L) was prepared by dissolving colourless liquid in OECD growth medium. The solution was kept in ultrasonic bath for 20 min. It was not possible to prepare homogenous solution of higher concentration. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the concentrations 0, 30, 45, 67, 100 and 150 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (EC50) for the test substance, (±)-menthone, in Desmodesmus subspicatus was determined to be 172.9 mg/L. This value indicates that the substance is likely to be non-hazardous to aquatic algae and can be considered as not classified as per the CLP criteria.

 

Similarly in the third study for the read across chemical (470-82-6) from authoritative database j-check 2017 having aim to determine the Growth Inhibition Test of (Cineole) 2-Oxabicyclo 2,2,2 octane, 1,3,3-trimethyl- to Alga (Pseudokirchneriella subcapitata) for the exposure period of 3 days. Test conducted according to OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test). Analytical monitoring was also done using the GC were the Frequency of analysis was at the start of exposure, after 4 hours from start of exposure, and at the end of exposure. Test solutions were prepared by mixing a stock solution of the test substance, which was prepared by adding and stirring the substance under the water surface of the Erlenmeyer flask filled with medium. Test performed on green algae Pseudokirchneriella subcapitata. Test was conducted at the different concentrations 500, 160, 50, 16, 5.0 mg/L (geometric ratio; square root of 10), control. Based on the growth rate inhibition of test organism Pseudokirchneriella subcapitata due to the direct contact with the chemical (Cineole) 2-Oxabicyclo 2,2,2 octane, 1,3,3-trimethyl- for 3 days, the effect concentration EC50 was 250 mg/l with the 95 % CL was 220 - 270 mg/L. and the NOEC was observed at the 16 mg/l. Thus on the basis of EC50, chemical was consider as nontoxic and not classified as toxic as per the CLP classification criteria.

 

Similarly in the fourth weight of evidence study for another read across chemical (540-88-5) from authoritative databases (HSDB and ECOTOX database) supports the nature of chemical. Toxicity study was carried out for determination of the nature of chemical tert-butyl acetate on the growth of aquatic algae and cyanobacteria. Test conducted under the static system for the total exposure period of 24 hrs. Based on the effect on Physiology and Assimilation efficiency of Chlorococcales (Green Algae Order), by the chemical tert-butyl acetate, the EC50 was determine at 1300 mg/l. Thus on the EC50 chemical tert-butyl acetate was concluded as nontoxic and not classified as per the CLP classification criteria. 

 

Based on the predicted data for the target chemical (from OECD QSAR 2018) and for the read across chemical from Lab report 2017 and authoritative databases (j-check, HSDB and ECOTOX database), it can be and concluded that the substance 3,3-Dimethyl-8,9-dinorbornan-2-one (1195-79-5) is considered to be not toxic to aquatic environment (aquatic algae and cyanobacteria) and cannot be classified as toxic as per the criteria mentioned in CLP regulation.