3-methyl-1,3-butanediol-1-ethylate

Toxicity to aquatic algae and cyanobacteria

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:

2018-10-10 to 2018-10-19

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)

Deviations:

yes

Remarks:

No impact on the experimentation results has been recorded.

Principles of method if other than guideline:

Deviation: A deviation occurred (EX045115) during experimentation, in the analytical sequence in the autosampler of the GC instrument has been put the vial of the blank instead of the vial of standard check 1. The standard check 1 has been put at the end of the sequence. No impact on the experimentation results has been recorded.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 2000, 625, 195.31, 61.04, 19.07 mL/L and control.
- Sampling method: Determination of concentration and stability of the test item has been determined using GC technique equipped with FID detector according to validated analytical method (other study report). The sample is considered stable if the measured concentration of the test item at the end of the test has been maintained within ± 20 % to the concentrations at the beginning of the test, according to OECD 201.
- Sample storage conditions before analysis: The samples are stored at room temperature until the beginning of the analytical study.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test item has been prepared at 2000 mg/L in culture medium. The test has been performed on the diluted nominal solutions. The total volume of the culture medium and the concentration of the algae inoculum added were the same in all vessels.
- Controls: Flasks were filled only with culture medium and algae.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Culture medium was used.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): Not reported.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: Green alga
- Strain: SAG 61.81
- Source (laboratory, culture collection): laboratory culture

ACCLIMATION
- Culturing media and conditions (same as test or not): The algal suspension in breeding has been kept in culture medium in sterile 250 mL Erlenmeyer flasks in the following conditions until the beginning of the test.
Temperature: 23°C ± 2°C
Lighting: lighting greater than 4300 lux
Stirring: Steady with electrical stirrer
- Any deformed or abnormal cells observed: No

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23.0 - 23.2 °C

pH:

Control:
test start: 7.84 - 7.84
test end: 7.82 - 7.91
Treatments:
test start: 7.71 - 7.86
test end: 7.19 - 8.10

Nominal and measured concentrations:

Nominal: 2000, 625, 195.31, 61.04, 19.07 mg/L
Measured (T=0): 2096.71, 644.76, 199.77, 63.33, 20.11 mg/L
Measured (T=72): 2001.69, 614.70, 189.06, 59.81, 19.08 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Material, size, headspace, fill volume: Glass, 250 mL
- Aeration: No
- Initial cells density: 10^4 cells/mL
- Control end cells density: 1.8 - 1.9 10^6
- No. of organisms per vessel: 10^4 cell/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The culture medium has been used as dilution water

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Photoperiod: Continuous
- Light intensity and quality: Fluorescent lamp 8000 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Burker chamber, every 24 h
- Other: At the end of the test, microscopic observation was performed to verify a normal and healthy appearance of the inoculum culture and to observe any abnormal appearance of the algae.

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 5 different concentrations have been prepared and tested with ten-fold dilutions from 100 mg/L to 0.1 mg/L.
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1 295 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

24.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no

Table 1: Stability of test item

Nominal conc.	Measured conc. (mg/L) T=0	Measured conc. (mg/L) T=72 h	% concentration variation	Stability
Treated (19.07 mg/L)	20.11	19.08	5.11	Stable
Treated (61.04 mg/L)	63.33	59.81	5.56	Stable
Treated (195.31 mg/L)	199.77	189.06	5.36	Stable
Treated (625.00 mg/L)	644.76	614.70	4.66	Stable
Treated (2000.00 mg/L)	2096.71	2001.69	4.53	Stable

 

Table 2: Validity criteria of the test

Parameter	Days	Result %	Validity criteria	Conformity
Growth rate	0-1	1.82	>0.92	CONFORM
	1-2	1.25
	2-3	2.13
%CVss	0-1	3.88	<35%
	1-2	9.55
	2-3	3.77
%CVwp	0-3	0.48	<7%

Table 3: Algae density (cells/mL) in treated groups

Time (days)	1	2	3
Treated group 2000.00 mg/L
0	1.0 E+04	1.0 E+04	1.0 E+04
1	1.3 E+04	1.2 E+04	1.2 E+04
2	5.5 E+04	5.5 E+04	7.2 E+04
3	6.3 E+04	6.7 E+04	7.8 E+04
Treated group 625.00 mg/L
0	1.0 E+04	1.0 E+04	1.0 E+04
1	1.3 E+04	1.3 E+04	1.5 E+04
2	1.3 E+05	1.4 E+05	1.4 E+05
3	3.2 E+05	3.5 E+05	3.6 E+05
Treated group 195.31 mg/L
0	1.0 E+04	1.0 E+04	1.0 E+04
1	2.2 E+04	2.2 E+04	2.5 E+04
2	1.8 E+05	1.9 E+05	1.9 E+05
3	4.7 E+05	4.5 E+05	4.6 E+05
Treated group 61.04 mg/L
0	1.0 E+04	1.0 E+04	1.0 E+04
1	2.7 E+04	2.7 E+04	2.3 E+04
2	1.5 E+05	1.6 E+05	1.7 E+05
3	8.5 E+05	8.5 E+05	8.8 E+05
Treated group 19.07 mg/L
0	1.0 E+04	1.0 E+04	1.0 E+04
1	4.0 E+04	3.2 E+04	4.3 E+04
2	1.5 E+05	1.7 E+05	1.9 E+05
3	9.3 E+05	9.8 E+05	1.1 E+06

 

Table 4: Algae density (cells/mL) in control groups

Time (days)	1	2	3	4	5	6
Control group
0	1.0 E+04	1.0 E+04	1.0 E+04	1.0 E+04	1.0 E+04	1.0 E+04
1	5.8 E+04	6.3 E+04	6.8 E+04	5.7 E+04	6.0 E+04	6.5 E+04
2	2.3 E+05	1.9 E+05	2.3 E+05	2.3 E+05	2.2 E+05	2.0 E+05
3	1.8 E+06	1.8 E+06	1.9 E+06	1.8 E+06	1.9 E+06	1.9 E+06

 

Table 5: Inhibition of growth rate (%)

Parameter	Treated (mg/L)
	2000.00	625.00	195.31	61.04	19.07
%Ir	62.87	32.10	26.46	14.45	11.81

 

Table 6: Determination of pH in control groups

ph Control
Replicate	pH (Start)	pH (end)	delta pHc	Validity criteria	Conformity
1	7.86	7.87	0.01	delta<1.5	VALID
2	7.86	7.84	0.02
3	7.85	7.91	0.06
4	7.84	7.86	0.02
5	7.87	7.85	0.02
6	7.84	7.82	0.02

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of 3-methyl-1,3-butandiol acetate was determined in an OECD 201 study with Pseudokirchneriella subcapitata and in compliance with GLP. Algae were exposed to the test substance in five different concentrations (2000, 625, 195.31, 61.04, 19.07 mg/L) for 72h. Test concentrations were analytically verified via GC-FID. The EC50 and Ec10 values after 72h were determined with 1295 mg/L and 24.5 mg/L based on nominal concentration.

Description of key information

ErC50 (72h) = 1295 mg/L

ErC10 (72h) = 24.5 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

1 295 mg/L

EC10 or NOEC for freshwater algae:

24.5 mg/L

Additional information

The toxicity of 3-methyl-1,3-butandiol acetate was determined in an OECD 201 study with Pseudokirchneriella subcapitata and in compliance with GLP. Algae were exposed to the test substance in five different concentrations (2000, 625, 195.31, 61.04, 19.07 mg/L) for 72h. Test concentrations were analytically verified via GC-FID. The EC50 and Ec10 values after 72h were determined with 1295 mg/L and 24.5 mg/L based on nominal concentration.