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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:
other: as mentioned below
Principles of method if other than guideline:
Prediction is done using QSAR Toolbox version 3.4
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material (as cited in study report): Nonylphenol ethoxylates
- Molecular formula : C17H28O2
- Molecular weight : 264.409 g/mol
- Substance type:Organic
- Physical state: Liquid
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:
24±1ᵒC
pH:
7.2 - 7.7
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
19.485 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 ( not "i") )  )  and "j" )  and "k" )  and ("l" and ( not "m") )  )  and ("n" and "o" )  )

Domain logical expression index: "a"

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

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Alcohol AND Alkane, branched with tertiary carbon AND Alkyl arenes AND Aryl AND Ether by Organic Functional groups

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Alcohol AND Alkyl arenes AND Ether AND Overlapping groups by Organic Functional groups (nested)

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Aliphatic Carbon [CH] AND Aliphatic Carbon [-CH2-] AND Aliphatic Carbon [-CH3] AND Aromatic Carbon [C] AND Hydroxy, aliphatic attach [-OH] AND Olefinic carbon [=CH- or =C<] AND Oxygen, aliphatic attach [-O-] AND Oxygen, one aromatic attach [-O-] AND Tertiary Carbon by Organic functional groups (US EPA)

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Alcohol AND Alkylarylether AND Aromatic compound AND Dialkylether AND Ether AND Hydroxy compound AND Primary alcohol by Organic functional groups, Norbert Haider (checkmol)

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 >> Polarised Alkenes-Michael addition OR Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated esters OR SN1 OR SN1 >> Iminium Ion Formation OR SN1 >> Iminium Ion Formation >> Aliphatic tertiary amines 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 OASIS v1.4

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 >> Carbamates  OR Acylation >> Ester aminolysis or thiolysis OR Acylation >> Ester aminolysis or thiolysis >> Carbamates  OR AN2 OR AN2 >> Michael-type addition to quinoid structures  OR AN2 >> Michael-type addition to quinoid structures  >> Substituted Phenols OR Radical reactions OR Radical reactions >> Free radical formation OR Radical reactions >> Free radical formation >> Organic peroxy compounds by Protein binding by OASIS v1.4

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Basesurface narcotics by Acute aquatic toxicity MOA by OASIS ONLY

Domain logical expression index: "k"

Similarity boundary:Target: CCCC(C)CC(C)Cc1ccc(OCCOCCOCCOCCOCCO)cc1
Threshold=30%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Not categorized by Repeated dose (HESS)

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Diethylene Glycol Alkyl Ethers (Less susceptible) No Rank OR Ethyleneglycol alkylethers (Hemolytic anemia) Rank A by Repeated dose (HESS)

Domain logical expression index: "n"

Parametric boundary:The target chemical should have a value of log Kow which is >= 1.55

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of log Kow which is <= 4.92

Validity criteria fulfilled:
not specified
Conclusions:
The median Effective concentration (EC50) value for Polyethylene glycol mono(branched p-nonylphenyl) ether on Desmodesmus subspicatus in a 72 hour study was estimated to be 19.5 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 Polyethylene glycol mono(branched p-nonylphenyl) ether (CAS no. 127087 -87 -0). EC50 value was estimated to be19.5 mg/l for Desmodesmus subspicatus for 72 h duration. Based on this value it can be concluded that the substance Polyethylene glycol mono(branched p-nonylphenyl) ether is considered to be toxic to aquatic environment and can be considered to be classified in aquatic chronic category 3 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 Polyethylene glycol mono(branched p-nonylphenyl) ether (CAS no. 127087 -87 -0) (2017). EC50 value was estimated to be 19.5 mg/l for Desmodesmus subspicatus for 72 h duration. Based on this value it can be concluded that the substance Polyethylene glycol mono(branched p-nonylphenyl) ether is considered to be toxic to aquaticenvironment and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
19.5 mg/L

Additional information

1 predicted datafor the target chemicalPolyethylene glycol mono(branched p-nonylphenyl) ether(CAS No. 127087-87-0) and the total 3 studies (2 studies from peer reviewed journal and 1 study from authoritative database) for its closest read across substance with logKow as the primary descriptor were reviewed for the toxicity to aquatic algae and cyanobacteria end point which are summarized as below:

 

Short term toxicity on aquatic algae and cyanobacteria of target chemical Polyethylene glycol mono(branched p-nonylphenyl) ether (CAS No. 127087-87-0), 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 be19.5 mg/l for Desmodesmus subspicatus for 72 h duration. Based on this value it can be concluded that the substance Polyethylene glycol mono(branched p-nonylphenyl) ether is considered to be toxic to aquatic environment and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

 

In a supporting weight of evidence study of read across chemical Polyethylene glycol nonylphenyl ether (CAS no. 9016 -45 -9) from peer reviewed journal (S.M. Bengtson Nash, et. al, 2005),short term toxicity to Scenedesmus subspicatus (green algae) study was carried out for greater than 70 mins using the ToxY-PAM bioassay. The study was based on the effects of theread acrosscompound Polyethylene glycol nonylphenyl ether (CAS no. 9016-45-9) on Scenedesmus subspicatus (green algae) in a static fresh water system at a temperature 24ᵒC.

Test chemical stock solutions were prepared in Milli-Q-water. Test chemical is completely soluble in water and standards were prepared by weight. Conc. of the test chemical used for the study were1, 10 and 100 mg/l, respectively. Test organism used for the study was Scenedesmus subspicatus obtained from Culture Collection of Algae and Protozoa, UK (CCAP). Test algae was grown in Jaworski’s media and Euglena gracilis medium. Cultures were maintained at room temperature (24±1◦C) on a natural daylight cycle receiving daylight of between 10 and 25 µE/m2/sec. The selected algae species were single celled and known not to form significant aggregates.

1mL of algal suspension pre-treated identically was added to each channel cuvette and the fluorescence measurements commenced. Once a satisfactory baseline had been achieved, indicating similar time-dependent responses in the two channels, 10µL of standard was added to channel 1. Both channel suspensions were stirred gently and the chamber caps replaced to protect the samples from external light.10µL of acidified (pH <3) Milli-Q water was added to the control channel simultaneously. Blank tests with 1% acetone using the bioassay did not indicate a significant reaction to the solvent. Two levels of fluorescence are measured with high accuracy by the ToxY-PAM dual-channel yield analyser, the basal fluorescence (F), shortly before application of the saturating pulse and maximal level (Fm’) reached during the saturation pulse. Both F and Fm’ were, in these tests, measured repetitively at 30 s intervals. From these two values, the PS-II quantum yield (Fm’−F)/ (Fm’), a measure of photosynthetic efficiency under ambient light conditions, could be calculated. Inhibition (%) of photosynthesis corresponds to the relative lowering of the quantum yield of the algae in the test channel with respect the algae in the control channel. The photosynthetic response was monitored on the ToxyWin chart. If a response peaked and stabilised, the average percent inhibition was calculated from 10 or more measurements (≥5 min) on the observed plateau. In the event that the response did not peak and stabilise within the maximum allowable test duration, the inhibition (%) was determined from the final 10 readings. Estimates of IC10 concentrations and their confidence intervals were made by fitting a linear regression to all four replicates of the tested toxicity concentration and inhibition values using the computer statistics program SPSS. Based on chlorophyll measurement of the test organism Scenedesmus subspicatus (green algae), the IC10 value was determined to be 56 mg/l, respectively.

 

For the same read across chemicalPolyethylene glycol nonylphenyl ether (CAS no. 9016-45-9), short term toxicity to Selenastrum capricornutum (green algae) study was carried out for 96 hrs (PHILIP B. DORN et. al, 1993). The study was performed according to EPA guideline.The study was based on the effects of the test compound Polyethylene glycol nonylphenyl ether on Selenastrum capricornutum (green algae) in a static fresh water system at a temperature of 25±2ᵒC. Reference toxicant controls were also conducted during the test program using Cu2 + and Cr6 + in 96 hrs exposures. Cell count of the test organism was determined after a period of 96 hrs and thus based on this NOEC, LOEC and EC50 value was determined. On the basis of effect on cell count of the test organism Selenastrum capricornutum (green algae), the 96 hr EC50, LOEC and NOEC value was determined to be 12, 16, 8 mg/l, respectively. Thus, based on the EC50 value, it can be concluded that the substance Polyethylene glycol nonylphenyl ether can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 3 as per the CLP criteria.

 

Additional weight of evidence study of short term toxicity to Scenedesmus quadricauda (green algae) study for read across chemical 4-Nonylphenol, ethoxylated (CAS no. 26027 -38 -3) was carried out for 48 hrs in a static fresh water system (ECOTOX database, 2016). On the basis of effect on developmental changes of the test organism Scenedesmus quadricauda (green algae), the 48 hr EC50 value was determined to be 17 mg/l, respectively.Thus, based on this value, it can be concluded that the substance 4-Nonylphenol, ethoxylated can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 3 as per the CLP criteria.

 

Based on the overall reported results for target chemicalPolyethylene glycol mono(branched p-nonylphenyl) ether(OECD QSAR toolbox version 3.4, 2017) and for its read across substance (from peer reviewed journal and authoritative database), it can be concluded that the test substancePolyethylene glycol mono(branched p-nonylphenyl) ethercan be considered astoxic to aquatic organisms and thus can be classified as aquatic chronic category 3 as per the CLP classification criteria.