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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
05/2017 - 07/2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Batch: 703709
Purity: 100 %
CoA: 2017-02-15
Analytical monitoring:
yes
Details on sampling:
Analytical samples were taken at 0 hours
(initial value) from fresh test solutions and after 72 hours from aged solutions from all test item
concentrations and control. For each sampling also a retain sample was taken.

All samples were stored deep frozen until they were transferred to the analytical laboratory.
Vehicle:
no
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
The algae are grown semi-continuously in sterile cultures in the laboratory. Old medium is
periodically replaced by fresh mineral solution in order to keep the algae in an exponential growth
state. Stock cultures are ordered regularly from our commercial supplier.
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Test temperature:
22.7 – 23.0 °C
pH:
7.47 – 7.99
Nominal and measured concentrations:
The following nominal test item concentrations were tested (spaced by a factor of 3.2): 100, 31.3,
9.77, 3.05 and 0.954 mg/L and control.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate is tested as the toxic reference item in a separate study twice a year to confirm the sensitivity of the test organism against compounds with known effects under the test conditions.
Key result
Duration:
72 d
Dose descriptor:
NOEC
Effect conc.:
ca. 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
and biomass
Remarks on result:
other: Following Dunnetts-t-test (left-sided, p<0.05)
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
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
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Reported statistics and error estimates:
The statistical evaluation for the 72 hours period was performed for growth rate and yield using
SAS® (2002–2010). A test for normality of the data was performed by calculating the Shapiro-Wilk
statistic and the homogeneity of variance of the data was evaluated by calculating the Levene
Test. The NOEC and LOEC were determined by using a multiple comparison method (Dunnetts-ttest,
left sided, for yield and growth rate). The calculation of the EC10, 20, 50 was not indicated since
the inhibition was below 10 % at all test item concentrations and hence the database was
inappropriate for probit analysis
Validity criteria fulfilled:
yes
Conclusions:
No statistically significant inhibitory effects on any parameter (growth rate, yield) were observed at
any of the test item concentrations, including the highest test item concentration of 100 mg/L
(nominal) at test end. Thus the overall LOEC was not determinable and the overall NOEC was
observed to be at 100 mg/L (nominal).
Due to an inhibition of all parameters (growth rate, yield) below 10 % the database was weak for
probit analysis, hence the EC10-, EC20- and EC50-values for growth rate and yield were considered
to be > 100 mg/L (nominal).
Executive summary:

Study Objective: The objective of this study was to determine the effects of IPDI-Uron on the growth of the single cell green alga Pseudokirchneriella subcapitata, to determine the no observed effect concentration (NOEC), to determine the lowest observed effect concentration (LOEC) and to determine the effect concentration (EC10, 20, 50), where possible.

Findings:

Validity criteria:

Biomass: Cell numbers, measured in the controls between 0 h and 72 hours, were found to increase by a factor of 62.86 for the control, which exceeds the threshold of 16. It corresponds to a growth rate of 1.37971 d-1.

Coefficient of Variation (section by section): The mean coefficient of variation for the section-by-section specific growth rates (hours 0 - 24, 24 - 48 and 48 - 72) in the control cultures was 22 % for the control and did not exceed 35 %.

Coefficient of Variation: (average growth): The coefficient of variation of average growth in replicate control cultures was 3.1 % for the control and did not exceed 7 % for the whole test period.

Test conditions: The pH-value of the control ranged from 7.47 to 7.99 during the test period, the temperature was measured to be 22.7 – 23.0 °C during the test and the

mean light intensity was 88.8 μEm-2s-1 at cell culture level.

Analytical Results: The measured initial concentration of IPDI-Uron was 100 % of nominal in the highest test item concentration of 100 mg/L. In the aged sample the measured content was 102 % of nominal. Therefore toxicological endpoints were evaluated using the nominal concentrations of the test item.

Description of key information

No statistically significant inhibitory effects on any parameter (growth rate, yield) were observed at
any of the test item concentrations, including the highest test item concentration of 100 mg/L
(nominal) at test end. Thus the overall LOEC was not determinable and the overall NOEC was
observed to be at 100 mg/L (nominal).
Due to an inhibition of all parameters (growth rate, yield) below 10 % the database was weak for
probit analysis, hence the EC10-, EC20- and EC50-values for growth rate and yield were considered
to be > 100 mg/L (nominal).

Key value for chemical safety assessment

EC50 for freshwater algae:
110 mg/L
EC10 or NOEC for freshwater algae:
110 mg/L

Additional information