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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:
The supporting QMRF report has been attached
Reference:
Composition 1
Qualifier:
according to
Guideline:
other: refer below principle
Principles of method if other than guideline:
The data is predicted using the OECD QSAR toolbox version 3.3 with logKow as the primary descriptor.
GLP compliance:
not specified
Test material information:
Composition 1
Specific details on test material used for the study:
- Name of test material: 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride
- Molecular formula: C8H9Cl3O
- Molecular weight: 227.517
- Smiles notation: O=C([C@@H]1C(C)(C)[C@@H]1\C=C(/Cl)Cl)Cl
- InChl: 1S/C8H9Cl3O/c1-8(2)4(3-5(9)10)6(8)7(11)12/h3-4,6H,1-2H3
- Substance type: Organic
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.:
0.7 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate

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 ( not "g") )  )  and "h" )  and "i" )  and ("j" and "k" )  )

Domain logical expression index: "a"

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

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Acyl halide OR Alkenyl halide OR Cycloalkane by Organic Functional groups ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Acyl halide OR Alkenyl halide OR Cycloalkane OR Overlapping groups by Organic Functional groups (nested) ONLY

Domain logical expression index: "d"

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 Chlorine, olefinic attach [-Cl] 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: "e"

Referential boundary: The target chemical should be classified as Acyl chloride OR Acyl halide OR Carbonic acid derivative OR Carboxylic acid derivative OR CO2 derivative (general) OR Halogen derivative by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Not possible to classify according to these rules by DPRA Cysteine peptide depletion

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as High reactive OR High reactive >> alpha,beta-carbonyl compounds with polarized multiple bonds OR High reactive >> Unsaturated acid anhydrides OR Low reactive OR Low reactive >> Acyl halides OR Moderate reactive OR Moderate reactive >> Glycidyl ether epoxides OR Moderate reactive >> Mono-methacrylic acid esters by DPRA Cysteine peptide depletion

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as High (Class III) by Toxic hazard classification by Cramer (original) ONLY

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Acid Halides AND Vinyl/Allyl Halides by Aquatic toxicity classification by ECOSAR ONLY

Domain logical expression index: "j"

Parametric boundary:The target chemical should have a value of log Kow which is >= -1.74

Domain logical expression index: "k"

Parametric boundary:The target chemical should have a value of log Kow which is <= 5.95

Validity criteria fulfilled:
not specified
Conclusions:
Using OECD QSAR toolbox version 3.3 the median Effective concentration (EC50) value for test chemical 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride on Desmodesmus subspicatus in a 72 hour study was estimated to be 0.7 mg/L on the basis of effects on growth rate.
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, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride. EC50 value was estimated to be 0.7 mg/l for Desmodesmus subspicatus for 72 h duration. This effect value indicating that the substance 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride (CAS no. 52314-67-7) pose a significant hazard to algae and thus consider to be classified in aquatic acute 1 as per the CLP classification criteria.

Description of key information

Using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride. EC50 value was estimated to be 0.7 mg/l for Desmodesmus subspicatus for 72 h duration. This effect value indicating that the substance 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride (CAS no. 52314-67-7) pose a significant hazard to algae and thus consider to be classified in aquatic acute 1 as per the CLP classification criteria.

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
0.7 mg/L

Additional information

Two studies including predicted data from validated tool and experimental data from authorative data source for toxicity to aquatic algae endpoint of test chemical 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride (Cas no. 52314-67-7) with relevant read across which is close to target using log Kow as primary descriptor were summarised as follows:

Using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the six closest read across substances, which indicate the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance chemical 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride (Cas no. 52314-67-7). The EC50 value was estimated to be 0.7 mg/l for Desmodesmus subspicatus for 72 h duration. 

And read across 2-Chloro-ethanoic acid (Cas no. 79-11-8) suggest Growth Inhibition Test of test chemical Chloroacetic acid (Cas no. 79-11-8) to Alga (Pseudokirchneriella subcapitata) was observed. In analytical method HPLC used as Separation method and MS used as Detection method. In experiment static condition maintained at 23 +/- 2 degree C test temp. and (nominal values) control, 0.0200, 0.0340, 0.0590, 0.100, 0.170, 0.300 mg/L with geometric ratio: 1.7 was used. Thus based on growth rate and area under the growth curve effect of the test organism Pseudokirchneriella subcapitata, the effect concentration (EC50) was observed to be 0.158 mg/l (95 % CL: 0.152 - 0.164 mg/L) and 0.0663 mg/l (95 % CL: 0.0500 - 0.0880 mg/L) respectively at 72 hrs exposure period. (Japan chemicals collaborative knowledge database (J-check), 2017)

Thus based on the effects from both studies give the conclusion that test substance 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-1-carbonyl chloride (Cas no. 52314-67-7) with effect concentrations in the range 0.158 to 0.7 mg/l was likely to be toxic to aquatic algae and can be classified in aquatic acute 1 category as per the CLP regulation.