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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Read across from toxicity study to aquatic invertebrates of pivalic acid (CAS 75-98-9), which is the hydrolysis product of trimethylacetic anhydride, is possible. Trimethylacetic anhydride ist not stable in water and hydrolyses within hours (For details see chapter 5.1.2).
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
- Purity (GC): 99,9%
- Purity (neutralization titration): 99.7%
- pKa: 4.69 (estimated value)
- Freezing point: 35.0 °C
Analytical monitoring:
yes
Details on sampling:
Sample collection frequency: Samples were taken from the new test solution at the start of exposure (0time) and from the old test solution at the end of exposure (72 hours)
Vehicle:
no
Details on test solutions:
The purity was not corrected because the purity of the test substance was 99.9% (GC) and 99.7% (neutralization titration). A concentrated solution having a test substance concentration of 2,500 mg/L was prepared, and this concentrated solution was diluted with test water to prepare a test solution.
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
Test Organism:
- Common name: Unicellular green algae
- Strain: ATCC22662
- Source: American Type Culture Collection
- Date of receipt: 2002-09-07
- Maintenance of obtained algae: Subcultured aseptically using slant culture medium of ATCC Culture Medium 625 (herein after referred to as ATCC medium)
- Result of susceptibility test: Reference substance (Potassium dichromate); exposure period December 13 - 17, 2010; ErC 50 (0-72 h) = 1.07 mg/L (95% confidence area: 0.98 to 1.16 mg/L); (Mean ± 2 standard deviation: 0.72 to 1.28 mg / L, N = 10 (test implementation period: from May 2005)) within the range specified by the institution)
- Long-lasting culture: The tested algae were subcultured from the slant culture medium into the ATCC medium and cultured under static conditions. (10-18 December 2010)
- Preculture: The cultivation was carried out under the same environmental conditions as the test (December 18 to 21, 2010)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
No data
Test temperature:
22.6-22.8 °C
pH:
- Not pH-adjusted test concentrations: 5.3-7.8
- pH-adjusted test concentration: 7.3-7.5
Dissolved oxygen:
No data
Salinity:
n.a.
Conductivity:
No data
Nominal and measured concentrations:
After 72 hours nominal test concentrations of 35, 45.5, 60.0, 77.5 and 100 mg/L equals measured arithmetic mean concentration of 36, 46.8, 59.2, 75.3 and 96.3 mg/L
Details on test conditions:
I. Test conditions:
- Test solution volume: 100 mL/tes vessel
- Stations: 3 container / test concentration group, pH adjustment test concentration group (60.0, 77.0 mg/L); 6 container/control area and pH adjustment test concentration area (100 mg/L)
- Initial biomass: At a cell concentration of 1.0 × 10 E+4 cells/mL (precultured algae)
- Test temperature: 23 +/- 2 °C
- Lighting: Continuous lighting by fluorescent light (wavelength range: 400 to 700 nm)
- pH: For the additional test concentration group, adjust to the pH value ± 0.3 of the control group
- Types of auxiliaries: None
- Auxiliary agent concentration in test solution: None

II. Setting test concentration '
- Prior to this test, preliminary tests were carried out in 5 test concentration groups with set concentrations of 6.25, 12.5, 25.0, 50.0 and loo mg / L with the common ratio being 2.0. Growth inhibition rates by the rate method after 72 hours were 0, 7%, -0.7%, -2.3%, 2.1% and 96.3%.
- In addition, as the pH value of the test solution fluctuates toward the acidic side by the addition of the test substance, a test concentration group of 100 mg/L concentration adjusted to the vicinity of the pH value of the OECD medium used for the test was set, and it was 72 hours The growth inhibition rate by the later velocity method was 1.7%.
- Based on the above results, in this test, the common ratio was set to 1.3, and five test concentration groups of 35.0, 45.5, 60.0, 77.5 and 100 mg/L without adjusting the pH value were selected as the test system without pH adjustment. In addition, test concentrations of 60.0, 77.5 and 100 mg/L adjusted to pH values ​​± 0.3 in the control group [Test system in which the pH value was adjusted to ± 0.3 in the control group] were added.
- For the 100 mg/L test concentration group where the pH value was adjusted, the number of consecutive vessels was set to 6, and for the test concentration group at 60.0 and 77.5 mg/L, triplicate. In addition, another control zone was established.

III. Test containers and equipment
- Test container: 300 mL glass Erlenmeyer flask (with breathable silicone stopper)
- Algae culture test apparatus: Constant temperature shake incubator (model: BR-300 LF)
- Optical microscope; Biological microscope manufactured by Olympus (model: BH 2)
- Particle counting apparatus: Cell counting analyzer manufactured by Beckman Coulter (model: Z 2)
- Water temperature gauge: Mercury rod type standard thermometer (measurement range: 0 to 50 ° C, minimum scale: 0.1 ° C)
- pH meter: CANNY ATC PH meter (model: D-21) written by Horiba Seisakusho
- Photon meter: Light meter manufactured by LICOR Co. (model: L1-250); Measurement wavelength range: 400 to 700 nm
Reference substance (positive control):
not specified
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
66 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (95%-confidence limit 65.6-66.3 mg/L)
Remarks:
without pH-adjustment
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
46.5 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
without pH-adjustment
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 96.6 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (95% confidence interval could not be calculated)
Remarks:
with pH-adjustment
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
96.6 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
with pH-adjustment
Validity criteria fulfilled:
yes
Conclusions:
During 72 hours of exposure an ErC50 of 66.0 mg/L and a NOEC of 46.5 mg/L were detected in the test system without pH-adjustment. In the test system in which the pH-value was adjusted to the pH value ± 0.3 of the control group an ErC50 of higher than 96.6 and a NOEC of 96.6 mg/L were received. The results relate to the arithmetic mean of the measured concentration.
Executive summary:

The study was conducted in accordance with the OECD Guidelines for the Testing of Chemicals No.201 "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" (2006). A range finding test was performed to get information about the test concentrations in the later main test. In the main test, algae were exposed to 5 test concentrations (35, 45.5, 60.0, 77.5 and 100 mg/L) relating to nominal concentrations under static exposure conditions. In addition, since the pH value of the test solution fluctuated to the acidic side due to the influence of the test substance, the test was conducted by adding the test concentration group in which the pH value was adjusted to pH - value ± 0.3 of the control group. The temperature and the pH-values were measured after 0 and 72 hours of exposure. The 50% growth inhibitory concentration (ErC50) and the maximum no-effect concentration (NOEC) were determined after 72 hours of exposure. During 72 hours of exposure an ErC50 of higher than 96.6 and a NOEC of 96.6 mg/L were received in the test system in which the pH value was adjusted to the pH value ± 0.3 of the control group. In the test system without pH-adjustment an ErC50 of 66.0 mg/L and a NOEC of 46.5 mg/L were detected. The results relate to the arithmetic mean of the measured concentration. This toxicity study is classified as acceptable and satisfies the guideline requirements for the Algae study.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Data from pivalic acid (CAS 75-98-9), which is the hydrolysis product of trimethylacetic anhydride.
Reason / purpose for cross-reference:
read-across source
Specific details on test material used for the study:
- Purity (GC): 99,9%
- Purity (neutralization titration): 99.7%
- pKa: 4.69 (estimated value)
- Freezing point: 35.0 °C
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
46.5 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
without pH-adjustment
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
66 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: (95%-confidence limit 65.6-66.3 mg/L)
Remarks:
without pH-adjustment
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 96.6 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
pH-adjustment
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
96.6 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other:
Remarks:
pH-adjustment
Validity criteria fulfilled:
yes
Conclusions:
The toxicity of pivalic acid (75 -98 -9) to algae was investigated in a static GLP study following OECD 201. During 72 hours of exposure an ErC50 of 66.0 mg/L and a NOEC of 46.5 mg/L were detected in the test system without pH-adjustment. In the test system in which the pH-value was adjusted to the pH value ± 0.3 of the control group an ErC50 of higher than 96.6 and a NOEC of 96.6 mg/L were received. The results relate to the arithmetic mean of the measured concentration.

Description of key information

The toxicity of pivalic acid (CAS 75-98-9) to algae was investigated in a static GLP study following OECD 201. During 72 hours of exposure an ErC50 of 66.0 mg/L and a NOEC of 46.5 mg/L were detected in the test system without pH-adjustment. In the test system in which the pH-value was adjusted to the pH value ± 0.3 of the control group an ErC50 of higher than 96.6 and a NOEC of 96.6 mg/L were received. The results relate to the arithmetic mean of the measured concentration.

Key value for chemical safety assessment

EC50 for freshwater algae:
66 mg/L
EC10 or NOEC for freshwater algae:
46.5 mg/L

Additional information

Read across from toxicity study to aquatic invertebrates of pivalic acid (CAS 75-98-9), which is the hydrolysis product of trimethylacetic anhydride, is possible. Trimethylacetic anhydride ist not stable in water and hydrolyses within hours (For details see chapter 5.1.2). 1