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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
December 2016 - March 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
impurity
Test material form:
liquid
Details on test material:
- Name of test material (as cited in the expert statement): Folenox
- Chemical name: 4,4,8,8-Tetramethyloctahydro-4a,7-methanonaphtho[1,8a-b]oxirene (IUPAC)
- Empirical formula: C15H24O
- Structural formula: See IUCLID section 1

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no
Details on test solutions:
Six replicates of exponentially growing algal cultures were exposed to a control, whereas three replicates per group were exposed to WAFs prepared at 0.10, 0.32, 1.0, 3.2 and 10 mg/L.
Samples taken from the WAFs at 0.10, 0.32, 1.0, 3.2 and 10 mg/L were analyzed and showed measured initial concentrations of 0.069, 0.21, 0.62, 1.5 and 4.4 mg/L, respectively. The latter is considered to be the solubility limit of Folenox in the test media (note: water solubility of Folenox is 4.9 mg/L). All concentrations decreased to 27-33% of initial at the end of the test. Given these results, the effect parameters were determined using the TWA concentrations that were calculated to be: 0.040, 0.12, 0.37, 0.94 and 2.3 mg/L.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Hardness:
24mg CaCO3/L
Test temperature:
Temperature of test medium was continuously measured in a temperature control vessel. During the exposure period the temperature measured in the incubator was maintained between 21 and 23°C. Temperature remained within the limits prescribed by the study plan (21-24°C, constant within 2°C).
pH:
pH 7.1 +/- 0.3
Nominal and measured concentrations:
Nominal: WAFs at 0.10, 0.32, 1.0, 3.2 and 10 mg/L loading rates
Measured (TWA): 0.040, 0.12, 0.37, 0.94 and 2.3 mg/L
Reference substance (positive control):
yes

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 2.3 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.3 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
Effects based on yield were also reported (see overall remarks and executive summary). However, the preferred observational endpoint in the algal inhibition study is growth rate because it is not dependent on the test design (ECHA guidance Chapter R.7b v1.1). The EU CLP regulation (No 1272/2008 and its adaption 286/2011) also states that classification should be based on the ErC50. Thus only the effects based on growth rate are presented in the above "effects concentration" table.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Executive summary:

Under the conditions of the present study withPseudokirchneriella subcapitata, Folenox concentrations at the maximum solubility achievable in test medium inhibited growth rate and yield of this fresh water algae species by 6 and 27%, respectively.

Hence, the 72h-EC50for inhibition of both growth rate (ERC50) and yield (EYC50) was >2.3 mg/L.

The 72h-NOEC for growth rate inhibition was 2.3 mg/L and the 72h-NOEC for yield inhibition was 0.37 mg/L.

The preferred observational end point in the algal growth inhibition test is growth rate because it is not dependent on the test design (ECHA guidance Chapter R.7b v1.1). The EU CLP regulation (No 1272/2008 and its adaption 286/2011) also states that classification should be based on the ErC50. Thus the 72-h EC50 and NOEC based on growth rate are used for classification purposes, which were determined in this study to be > 2.3 mg/L and 2.3 mg/L respectively.