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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:
read-across from supporting substance (structural analogue or surrogate)
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:
The analogue approach is used for the hazard assessment of toxicological endpoints for the registration of the target substance trimethylolpropane ricinoleate (CAS 68551-65-5) based on generation of different breakdown/metabolic products, resulting not only in similar physical and biological systems (Scenario 2 of the Read-Across Assessment Framework (RAAF, ECHA, 2015) but also consequently in similar physico-chemical, environmental fate and ecotoxicological properties. The source compounds are fatty acids, C16-18 and C18-unsatd., esters with pentaerythritol (CAS 85711-45-1) and pentaerythritol ricinoleate (CAS 78-22-8). It is proposed that the different alcohols resulting from ester hydrolysis of the source compounds and the target substance will not result in significant variation in environmental or biological effects.
Neither target nor source compounds are classified for hazardous effects associated with aquatic toxicity. The use of reliable experimental data, all evaluated as reliable according to Klimisch scores of 1 or 2, to estimate the ecotoxicity of the registered substance is adequate for the purposes of fulfilling the data requirements of registration and classifying potential hazards. Similar grouping into categories has been accepted by other regulatory agencies (U.S. EPA, 2010; U.S. FDA for food notifications). Thus, this read-across approach is adequate for the purposes of risk assessment and classification and labeling.


Reason / purpose for cross-reference:
read-across source
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
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 an analogue 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