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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 March 2018 to 23 April 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Reliable experimental study following OECD 201 guidelines (2006) and EC No. 761/2009 Method C.3 adopted 2009 and GLP standards.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
2006
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
2009
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
The test substance is listed as 2-Hydroxyethyl Ricinoleate (CAS # 106-17-2). The test substance is a clear yellow viscous liquid. The test substance was obtained from the Sponsor, Vertellus Holdings LLC and stored at room temperature in the dark.
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
The test was carried out using Pseudokirchneriella subcapitata strain CCAP 278/4. Liquid cultures of Pseudokirchneriella subcapitata were obtained from the Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland. Master cultures were maintained in the laboratory by the periodic replenishment of culture medium. The master cultures were maintained in the laboratory under constant agitation by orbital shaker (100 to 150 rpm) and constant illumination at 24 ±1 °C.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 °C ± 1 °C
pH:
7.6 – 7.8
Nominal and measured concentrations:
Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to solutions of the test item at nominal concentrations of 1.0, 3.2, 10, 32 and 100% v/v saturated solution.
Details on test conditions:
Preliminary solubility work conducted indicated that the test item was practically insoluble in water using traditional methods of preparation e.g. ultrasonication and high shear mixing. Based on this information the test item was categorized as being a ‘difficult substance’ as defined by the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures (OECD 2000). Therefore, a media preparation trial was conducted in order to determine the solubility of the test item under test conditions.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate wss tested as the reference item at concentrations of 0.25 mg/L, 0.50 mg/L, 1.0mg/L, 2.0 mg/L and 4.0 mg/L.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.76 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Effect level value is the arithmetic mean of the three geometric means of the measured test concentrations for each observation period 0-24, 24-48 and 48-72 h.
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Effect level value is the arithmetic mean of the three geometric means of the measured test concentrations for each observation period 0-24, 24-48 and 48-72 h.
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.97 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Effect level value is the arithmetic mean of the three geometric means of the measured test concentrations for each observation period 0-24, 24-48 and 48-72 h.
Results with reference substance (positive control):
The results from the positive control with potassium dichromate were within the normal ranges for this reference item.
Validity criteria fulfilled:
yes
Remarks:
Cell conc. of control increased by a factor of 230 after 72 h (protocol ≥ factor of 16); mean of coeff. of var.for growth rates control 14% (protocol ≤ 35%); coeffof var. of avg. sp. growth rate in replicate control cultures 5% (protocol ≤ 7%).
Conclusions:
The test substance caused a reduction of growth in the algal cultures (test units) exposed to test concentrations of the test item for 72 hours; therefore,inhibitory effects were observed All effects levels were calculated using an arithmetic mean of three geometric means of the measured test concentrations for each observation period 0-24, 24-48 and 48-72 h . The 72-h EC50 was reported as 0.76 mg/L; the 72-h NOEC and the 72-h LOEC were reported as 0.25 mg/L and 0.97 mg/L, respectively.


Description of key information

The key study was a static acute toxicity test on the effects of the substance on the freshwater unicellular green alga, Pseudokirchneriella subcapitata following OECD Guideline 201.  Exposure of the algae to the test substance for 72 hours resulted in a a reduction of growth in the algal cultures (test units); therefore, inhibitory effects were observed.  All effects levels were based upon measured concentrations (calculated based on the geometric mean). The 72-h EC50 was reported as 0.76 mg/L; the 72-h NOEC and the 72-h LOEC were reported as 0.25 mg/L and 0.97 mg/L, respectively.

 

 

Key value for chemical safety assessment

EC50 for freshwater algae:
0.76 mg/L
EC10 or NOEC for freshwater algae:
0.25 mg/L

Additional information