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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
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Samples were collected of the Stock Solution (WAF) and of each treatment at the beginning and end of exposure for analysis.
Vehicle:
no
Details on test solutions:
Algae medium was prepared in accordance with OECD 201. Specifically, the AAP
medium specified in Annex 3 from that method was used. Algae medium was prepared
using deionized water (DI). Each of the stock solutions was prepared in DI (Table 2).
One ml of each stock was added to a flask and diluted to one liter with DI water. This
water was mixed on a magnetic stir plate and filtered through a 0.2-micron filter for
sanitization. This medium was used for all culturing and testing of algae for this study.

Component Concentration in Prepared Medium mg/L
NaHCO3 15.0
NaNO3 25.5
MgCl2-6(H2O) 12.16
CaCl-2(H2O) 4.41
MgSO4-7H2O 14.6
K2HPO4 1.044
FeCl3-6(H2O) 0.160
Na2EDTA-2(H2O) 0.300
H3BO3 0.186
MnCl2-4(H2O) 0.415
ZnCl2 0.00327
CoCl2-6(H2O) 0.00143
Na2MoO4-(H2O) 0.00726
CuCl2-2(H2O) 0.000012
Test organisms (species):
other: Raphidocelis subcapitata
Details on test organisms:
An algal starter culture was purchased from Aquatic Biosystems, Inc. (Fort Collins,
Colorado) prior to testing. BMI cultures were inoculated at 104 cells/ml and allowed to
incubate for 72 hours. Cell counts were performed to ensure logarithmic growth. Testing
was performed using these cultures.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Details on test conditions:
All testing and reporting were conducted as per OECD 201 (2006). The study consisted of a range-finding and a definitive test. Unicellular green algae (Raphidocelis
subcapitata) were exposed to different concentrations of the product in algae medium . Cell density was monitored daily throughout the study via direct counts.
The endpoints were EC10 and EC50 for inhibition. A summary of the test conditions is

Test Requirement Condition
1. Test type: Static
2. Renewal of test solutions: Not Renewed
3. Temperature (°C): 22 + 2°C
4. Light quality: Full Spectrum
5. Light intensity: 60 - 100 μE/(m-2 s-1)
6. Photoperiod: Continuous
7. Size of test vessel: 250 ml
8. Volume of test solution: 100 ml
9. Cell Density at test initiation: 104 cells/ml
11. Number of replicates per concentration: 3
14. Aeration: None
15. Medium: See section 3.2
16. Test duration: 72 hours
17. Test concentrations: Five product concentrations and a control
18. Dilution series: 0.1 dilution series for range-finding test
0.5 dilution series for definitive test
19. Endpoint: Growth Inhibition
20. Sampling and sample: Treatments were prepared from WAF
21. Test acceptability criterion: Biomass of control cultures increase by a factor of at
least 16. Section – by – section specific growth rate
coefficient of variation not more than 35%.
Coefficient of variation during the whole test period
not greater than 7% in the controls.
Reference substance (positive control):
yes
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.299 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
not determinable
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.756 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The results of the range-finding study suggested that the endpoint would fall between 0.1 and 1.0 mg/L (Nominal WAF). Therefore, nominal treatments for the definitive test were 0, 0.0625, 0.125, 0.25, 0.5 and 1.0 mg/L WAF.
Treatment
(mg/L nominal
WAF) 72h Cell Count (Count X 104) Percent Inhibition
0 53 NA
.1 62 0
1 8 88
10 1 98
100 0 100
1000 0 100


Table presents a summary of the results from the toxicity test.

Summary of Algal Inhibition Toxicity Results
Measured Concentration (mg/L) 72h Cell Count (Average) Specific Growth Rate Percent Inhibition
0 54.3 0.056 NA
0.048 61 0.057 0
0.095 64.7 0.058 0
0.19 48.7 0.054 2.8
0.38 34.3 0.049 11.6
0.76 7.7 0.028 49.2
Validity criteria fulfilled:
yes
Conclusions:
Freshwater Alga and Cyanobacteria, Growth Inhibition Test (OECD 201: 2006) was performed with test substance Isophoronediamine-Cresyl Glycidyl Ether Adduct. The EC10 for specific growth rate was 0.299 mg/L based on measured concentrations. The EC50 for specific growth rate was 0.756 mg/L.
Executive summary:

Freshwater Alga and Cyanobacteria, Growth Inhibition Test (OECD 201: 2006) was performed with test substance Isophoronediamine-Cresyl Glycidyl Ether Adduct. The EC10 for specific growth rate was 0.299 mg/L based on measured concentrations. The EC50 for specific growth rate was 0.756 mg/L.

Description of key information

Freshwater Alga and Cyanobacteria, Growth Inhibition Test (OECD 201: 2006) was performed with test substance Isophoronediamine-Cresyl Glycidyl Ether Adduct. The EC10 for specific growth rate was 0.299 mg/L based on measured concentrations. The EC50 for specific growth rate was 0.756 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.756 mg/L

Additional information