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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
Qualifier:
according to guideline
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Prediction is done using OECD QSAR Toolbox version 3.4 with logKow as the primary descriptor.
GLP compliance:
not specified
Specific details on test material used for the study:
- IUPAC name: 3-phenylpropanoic acid
- Molecular formula: C9H10O2
- Molecular weight: 150.176 g/mol
- Smiles: c1(CCC(O)=O)ccccc1
- InChI: 1S/C9H10O2/c10-9(11)7-6-8-4-2-1-3-5-8/h1-5H,6-7H2,(H,10,11)
- 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
Test temperature:
22.4 - 23.1°C
pH:
7.92 - 8.10
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
122.962 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" )  and "e" )  and ("f" and ( not "g") )  )  and ("h" and ( not "i") )  )  and "j" )  and "k" )  and "l" )  and ("m" and ( not "n") )  )  and ("o" and ( not "p") )  )  and ("q" and ( not "r") )  )  and ("s" and "t" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Aryl AND Carboxylic acid by Organic Functional groups

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Aryl AND Carboxylic acid by Organic Functional groups (nested)

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Acid, aliphatic attach [-COOH] AND Alcohol, olefinic attach [-OH] AND Aliphatic Carbon [CH] AND Aliphatic Carbon [-CH2-] AND Aromatic Carbon [C] AND Carbonyl, aliphatic attach [-C(=O)-] AND Miscellaneous sulfide (=S) or oxide (=O) AND Olefinic carbon [=CH- or =C<] by Organic functional groups (US EPA)

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Acid, aliphatic attach [-COOH] AND Alcohol, olefinic attach [-OH] AND Aliphatic Carbon [CH] AND Aliphatic Carbon [-CH2-] AND Aromatic Carbon [C] AND Carbonyl, aliphatic attach [-C(=O)-] AND Miscellaneous sulfide (=S) or oxide (=O) AND Olefinic carbon [=CH- or =C<] by Organic functional groups (US EPA)

Domain logical expression index: "e"

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: "f"

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

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Aromatic diazo (Genotox) OR Aromatic mono-and dialkylamine (Genotox) OR Halogenated benzene (Nongenotox) OR o-phenylphenol (Nongenotox) OR Structural alert for genotoxic carcinogenicity OR Structural alert for nongenotoxic carcinogenicity OR Structural alerts for both genotoxic and nongenotoxic carcinogenicity by Carcinogenicity (genotox and nongenotox) alerts by ISS

Domain logical expression index: "h"

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

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Alkali Earth OR Alkaline Earth OR Halogens OR Transition Metals by Groups of elements

Domain logical expression index: "j"

Similarity boundary:Target: OC(=O)CCc1ccccc1
Threshold=30%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "k"

Similarity boundary:Target: OC(=O)CCc1ccccc1
Threshold=60%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "l"

Similarity boundary:Target: OC(=O)CCc1ccccc1
Threshold=40%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "m"

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

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Ring opening acylation OR Acylation >> Ring opening acylation >> beta-Lactams  by Protein binding alerts for skin sensitization by OASIS v1.4

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Inclusion rules not met by Eye irritation/corrosion Inclusion rules by BfR

Domain logical expression index: "p"

Referential boundary: The target chemical should be classified as Derivatives of alpha amino benzene OR Organic phosphonic acids and their derivatives OR Substituted indoles by Eye irritation/corrosion Inclusion rules by BfR

Domain logical expression index: "q"

Referential boundary: The target chemical should be classified as No Data by Ultimate biodeg

Domain logical expression index: "r"

Referential boundary: The target chemical should be classified as 1 to 10 days by Ultimate biodeg

Domain logical expression index: "s"

Parametric boundary:The target chemical should have a value of log Kow which is >= 0.166

Domain logical expression index: "t"

Parametric boundary:The target chemical should have a value of log Kow which is <= 4.33

Validity criteria fulfilled:
not specified
Conclusions:
The median Effective concentration (EC50) value for 3-phenylpropanoic acid on Desmodesmus subspicatus in a 72 hour study was estimated to be 122.96 mg/L on the basis of effects on growth rate.
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, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 3-phenylpropanoic acid (CAS no. 501 -52 -0). EC50 value was estimated to be 122.96 mg/l for Desmodesmus subspicatus for 72 h duration. Based on this value it can be concluded that the substance 3-phenylpropanoic acid is considered to be non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

Description of key information

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, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 3-phenylpropanoic acid (CAS no. 501 -52 -0) (2017). EC50 value was estimated to be 122.96 mg/l for Desmodesmus subspicatus for 72 h duration. Based on this value it can be concluded that the substance 3-phenylpropanoic acid is considered to be non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
122.96 mg/L

Additional information

2 predicted data for the target chemical 3 -phenylpropanoic acid (CAS No. 501 -52 -0) and total 3 weight of evidence studies for its read across substance were reviewed to summarize the following information:

 

Short term toxicity on aquatic algae and cyanobacteria of target chemical 3-phenylpropanoic acid (CAS No. 501-52-0) is predicted using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances (2017).EC50 value was estimated to be 122.96 mg/l for Desmodesmus subspicatus for 72 h duration. Based on this value it can be concluded that the substance 3-phenylpropanoic acid is considered to be non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

 

In another prediction done using the EPI Suite ECOSAR version 1.10, the short term toxicity on green algae was predicted for test substance 3 -phenylpropanoic acid (CAS No. 501 -52 -0).On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance is estimated to be 330.938 mg/l for green algae for 96 h duration. Based on this value, it can be concluded that the test chemical 3 -phenylpropanoic 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.

 

In a supporting study of the read across chemical Benzyl butyrate(CAS no. 103-37-7), the effect of the substance was studied on the growth of fresh water green alga Chlorella vulgaris [UERL study report, Sustainability Support Services (Europe) AB, Report no. 103-37-7/01/2015/AT, 2015]. The study was conducted following OECD guideline 201- Alga growth inhibition test. The test concentration chosen for the study were 6.25mg/L, 12.5mg/L, 25mg/L, 50 mg/L, 100mg/L and 200mg/L. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be >200mg/L.Based on this value it can be concluded that the substanceBenzyl butyrateis considered to be non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

For another read across chemical Benzoic acid (CAS no. 65-85-0), short term toxicity study was carried out using cyanobacteria (blue-green algae) Anabaena inaequalis, A. cylindrica, and A.variabilis, and the green algae Chlorella pyrenoidosa and Scenedesmus quadricauda as a test organism (GLENN W. STRATTON & CHARLES T. CORKE, 1982). The study was based on the effects of the read across compound Benzoic acid (CAS no. 65-85-0) on algae in a static fresh water system. Read across chemical was obtained from Aldrich Chemical Co., Milwaukee, Wisconsin, USA. Stock solutions of test chemical were prepared in pesticide grade acetone. The proper level of acetone (0.1 %v/v) to use in each bioassay system was determined using the solvent-pesticide interaction analysis technique. Chemical was tested at a minimum of five concentrations ranging from 0 to 100 mg/l (nominal concentration). Test organisms used for the study include (blue-green algae) Anabaena inaequalis, A. cylindrica, and A.variabilis, and the green algae Chlorella pyrenoidosa and Scenedesmus quadricauda, respectively.

Cultures of Anabaena inaequalis and A. cylindrica were maintained in a liquid nitrogen-free medium at a temperature of 20°C and a light intensity of 7000 lux on a 12 h light-dark cycle whereas the other cultures such as A.variabilis, Chlorella pyrenoidosa and Scenedesmus quadricauda were maintained under the same conditions except the growth medium was supplemented with 1.5 g NaNO3/l. Photosynthesis was assayed by following the uptake of 14CO2 from NaH14CO3 (Amersham/Searle, Oakville, Ontario, Canada). Plastic tissue culture flasks with a total internal volume of 74 ml were employed as assay chambers. Each contained 9.9ml of cell suspension (containing 6-5 × 10(4)cyanobacterial or 1.0 × 10(5)green algal cells/ml), 0.1 ml of radioisotope (to give a final activity of 0.1µCi/ml) and 0.01 ml of read across chemical. The flasks were incubated for 3 h and photosynthetic activity was assayed. Per cent inhibition values were calculated relative to photosynthetic activity in control systems (solvent only) and EC50 values determined by probit or regression analysis, where applicable. Analyses for significant differences (p = 0.05) were performed using Dunnett's test and Duncan's multiple range test.

Based on the effect of Benzoic acid on the photosynthesis of the test organisms, the EC50 value was determined to be 5, 60, 55, 60 and 75 mg/l for Anabaena inaequalis, A. cylindrical, A.variabilis, Chlorella pyrenoidosa and Scenedesmus quadricauda respectively. Thus, based on this value, it can be concluded that the read across chemical Benzoic acid can be considered as toxic to aquatic organisms. Since the chemical is readily biodegradable in nature, Benzoic acid can be considered as non-toxic to aquatic organisms and thus cannot be classified as hazardous as per the CLP criteria.

 

Another short term toxicity to algae study from authoritative database (J-CHECK, 2016) for the read across chemical Salicylic acid (CAS no. 69-72-7) was carried out for 72 hrs. The study was based on the effects of the read across compound Salicylic acid on algae in a static fresh water system. Based on effect on growth rate of algae, the 72 hr EC50 and NOEC value was determined to be 65 and 31 mg/l and on the basis of area under the growth curves, the 72 hr EC50 and NOEC value was determined to be 41 and 17 mg/l, respectively. Thus, based on EC50 value, it can be concluded that the substance Salicylic acid can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 3. Since the chemical is readily biodegradable in nature, Salicylic acid can be considered as non-toxic to aquatic organisms and thus cannot be classified as hazardous as per the CLP criteria.

 

Thus, based on the overall reported results for target chemical 3-phenylpropanoic acid (OECD QSAR toolbox version 3.4 and EPI suite, 2017) and for its read across substance (from UERL study report, peer reviewed journal and authoritative database), it can be concluded that the test substance 3 -phenylpropanoic acid can be considered as non-toxic to aquatic environment and thus can be considered to be not classified as per the CLP classification criteria.