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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:
15 February 2018 to 18 February 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
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
2006
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
2009
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
The test substance is listed as Castor Oil PE Ester (CAS No.78-22-8). The test substance was obtained from the Sponsor, Vertellus Specialties Material and stored at room temperature.
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, formerly known as Selenastrum capricornutum. The parent stock was obtained from the Department of Botany, Culture Collection of Algae, University of Texas at Austin, on 18 July 2017. The parent stock was identified as Selenastrum capricornutum. The prepared cultures were maintained in a temperature-controlled environmental chamber under continuous light. Periodically, new cultures were cloned from an existing culture derived from the parent stock. All cultures were maintained under the same conditions as those used for testing. The algal culture used for this test was two days old and the biomass had increased exponentially (i.e., specific growth rate of 1.7 day-1) during the culture period.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
23.9 °C to 25.1 °C
pH:
7.7 to 7.9
Nominal and measured concentrations:
Following a preliminary range-finding test, a definitive ltest was conducted with nominal concentrations of 0 (control), 1.2, 3.7, 11, 33, and 100 mg TP/L using a water accommodated fraction (WAF).
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Test solution prepared as a Water Accommodated Fraction (WAF).
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
11 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
Test solution prepared as a Water Accommodated Fraction (WAF).
Validity criteria fulfilled:
yes
Remarks:
Cell conc.of control increased by a factor of >16 after 72 h (protocol ≥ factor of 16); mean of coeff.of var. for growth rates control <35% (protocol ≤ 35%); coeffi. of var. of avg. specific growth rate in replicate control cultures <7% (protocol ≤ 7%).
Conclusions:
The test substance caused a slight reduction of growth in the algal cultures (test units) exposed to a series of nominal test concentrations of the test item prepared with a water accommodated fraction (WAF) for 72 h. The 72-h ELR50 (based on growth rate) was > 100 mg TP/L. The 72-h NOELR (based on growth rate) was 11 mg TP/L).

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. The test substance caused a slight reduction of growth in the algal cultures (test units) exposed for 72 hours to a series of nominal test concentrations of the test item prepared with a water accommodated fraction (WAF).  The 72-h ELR50 (based on growth rate) was reported as > 100 mg TP/L. The 72-h NOELR (based on growth rate) was reported as = 11 mg TP/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
11 mg/L

Additional information