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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:
January 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
impurity
Type:
impurity
Type:
impurity
Test material form:
liquid
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: PE00120812
- Expiration date of the lot/batch: 09 Jul 2017
- Purity test date: 78.4% (two main peaks)

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Test vessels (50 mL conical flasks) were prepared which were sealed and contained sufficient media (50 ml) to leave as minimum a headspace as possible in order to minimize any potential losses through volatility. Each test vessel was inoculated with 1 x 104 algae cells/mL and incubated at 21 - 24°C for 72 hours with biomass determination and analytical determination of substance concentration at 24-hour intervals.

Test solutions

Vehicle:
yes
Details on test solutions:
The test substance was known to have limited solubility in the test medium. It was therefore considered that the most appropriate method of dissolution of the test substance was to prepare dilution series in acetone and to directly dose finite amounts of the substance with a solvent spike experiment (final level of acetone 100μl / 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:
yes
Total exposure duration:
72 h

Test conditions

Test temperature:
The results of the environmental conditions and water pH determinations are presented in Table 3 in the attached report.
pH:
The results of the environmental conditions and water pH determinations are presented in Table 3 in the attached report.
Dissolved oxygen:
The results of the environmental conditions and water pH determinations are presented in Table 3 in the attached report.
Nominal and measured concentrations:
The test was conducted at nominal test concentrations of 1.0, 3.2, 10, 32 and 100 mg/L (0.52, 1.59, 5.16, 16.37 and 37.97 mg/L based on time-weighted mean measured concentrations). A control group and a solvent control group were also included.
Reference substance (positive control):
yes

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
25.48 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
5.17 mg/L
Conc. based on:
test mat.
Basis for effect:
other: Yield
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
66.96 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Extrapolated value, 50% inhibition of growth rate not achieved at maximal concentration tested
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
5.17 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
20.75 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- All inhibition values are calculated in relation to the solvent control.
- Analysis of Jasmonyl in test media was performed at 0, 24, 48 and 72 hours. Test concentration remained stable over the first 24 hours, followed by accelerated decline. At 72 hours, analysis of the test samples showed measured concentrations below the LOD.
- All analysis was performed by summing up the area of the two peaks of the main components. The two peaks of the test compound were degraded at the 72 hour time point, and two new degradation products (probably alcohols formed by ester hydrolysis) are observed (see figure 5 and 6 in full study report). A control sample incubated under test conditions without algal cells showed similar degradation over time (data not shown), confirming that loss of the substance is due to abiotic degradation.
- Due to the loss over time, results have been based on time-weighted mean (TWM) measured concentrations, whereby the limit for detection was used for calculation in samples in which the substance was no longer detected.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Based on time-weighted mean measured test concentrations, the 72-hour EyC50 and the 0-72 hour ErC50 values were calculated to be 25.48 and 66.96 mg/L, respectively. The corresponding 72-hour EyC10 and the 0-72 hour ErC10 values were 9.85 and 20.75 mg/L. The corresponding NOEC values for yield and specific growth rate after 72 hours were at 5.17 mg/L. All validity criteria were met, therefore the test was considered valid.

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. The preferred observational endpoint in long-term studies is the EC10 value because it is derived from the dose response curve. In contrast the NOEC depends on the experiment design (e.g. the concentrations used in the test). Thus the 72-h EC50 and EC10 based on growth rate are used for classification purposes, which were determined in this study to be 66.96 mg/L and 20.75 mg/L respectively.