Butyl decanoate

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:

04 - 07 Sep 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2011

Deviations:

yes

Remarks:

The light intensity was 520 lx below and 420 lx above the recommended range. The range was also outside the ± 15% recommended range stated in OECD 201. A minimum temperature of 20.4°C was recorded, 0.6°C below the OECD 201 recommended range.

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of certificate: 11.03.2017 (The Department of Health of the Government of the United Kingdom)

Test material

Test material information

Constituent 1

Reference substance name:

Butyl decanoate

EC Number:

250-280-5

EC Name:

Butyl decanoate

Cas Number:

30673-36-0

Molecular formula:

C14H28O2

IUPAC Name:

butyl decanoate

Test material form:

liquid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all concentrations, taken at start and end of the 72 hour exposure period.
- Sampling method: Samples were taken from remaining test media after filling test vessels for 0 hours and pooled replicate flasks for 72 hours.

Test solutions

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Stock solutions were prepared separately by adding the appropriate amount of test substance to solvent (DCM). The total volume of the solvent in the stock solution was 10 mL. The test concentrations were prepared by adding 50 µL of the corresponding stock solution to a total volume of 500 mL of algae medium. Measured amounts of stock solution was added to the correct amount of dilution water.
- Chemical name of vehicle: Methanol for the range finding test and Dichloromethane (DCM) for the definitive test.
- Volume of solvent in solvent control: 50 µL

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: CCAP 278/4
- Source: Culture Collection of Algae and Protozoa, SAMS Ltd, Scottish Marine Institute, OBAN, Argyll PA37 1QA, Scotland, United Kingdom.
- Method of cultivation: In Deionised water with added nutrients according to OECD 201. Temperature: 21.0 – 21.3°C, Illumination: 5480 - 7910 lx continuous white light, Orbiting: set to 200 rpm

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

20.4 – 21.7°C

pH:

7.81 – 8.40

Nominal and measured concentrations:

Nominal test substance concentrations: solvent control (DCM), 0 (control), 0.625, 1.250, 2.5, 5, 10 mg/L
Mean measured concentrations: 0 (control), 0.134, 0.376, 0.410, 1.201, 1.579 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: conical flask, glass (nominal 250 mL)
- Fill volume: 100 mL
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Deionised water with added nutrients according to OECD 201

OTHER TEST CONDITIONS
- Sterile test conditions:no
- Adjustment of pH:no
- Photoperiod: continuous white light
- Light intensity and quality: 5480 - 8420 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Cell densities were measured microscopically in sextuplicate at 24 hours for the control and triplicate thereafter, and in triplicate at 24, 48 and 72 hours (±2h) for the test concentrations by direct cell counts using a haemocytometer and microscope.

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: solvent control (methanol), 0, 0.1, 1.0, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: EC50 (72 h): 1 - 10 mg/L (nominal)

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.731 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.679 - 0.793 (95% confidence limits)

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.394 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.388 - 0.401 (95% confidence limits)

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.376 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in control and solvent control: yes
- Observation of abnormalities: no

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 0.657 mg/L (date 23 to 26 July 2018)

Reported statistics and error estimates:

The EC50 values were calculated against the solvent control and where possible, estimated graphically with 95% confidence limits calculated according to the method of ToxCalc™ Version 5.0 “Comprehensive Toxicity Data Analysis and Database Software”, copyright 1994-1996.

Any other information on results incl. tables

Table 1: Percent inhibition

Mean measured concentration (mg/L)	Percent reduction in growth rate		Percent reduction in yield
	0 - 48 hours	0 - 72 hours	0 - 48 hours	0 - 72 hours
0.134	-39	-12	-125	-58
0.376	-40	-11	-122	-53
0.410	19	13	41	40
1.201	81	95	91	99
1.579	97	100	98	100

Note: Negative numbers indicate an increase in growth compared to the solvent controls.

Table 2: Mean initial cell density: Approximately 1 x 10⁴cells/ml based upon inoculation volume, not counted microscopically.

Mean measured concentration (mg/L)	Replicate	Cell density measurements (cells/ml x 10^4)
		24 hours	48 hours	72 hours
0 (Control)	1	5.5	28.0	93.7
	2	4.3	20.7	74.3
	3	3.3	17.0	64.7
	4	2.3	18.3	66.0
	5	3.8	19.7	76.0
	6	4.7	24.7	88.7
	Mean	4.0	21.4	77.2
Solvent control	1	2.3	13.0	64.7
	2	2.0	13.7	55.7
	3	2.3	8.3	38.0
	4	2.5	10.3	41.7
	5	1.7	4.7	45.0
	6	1.5	3.7	38.0
	Mean	2.1	9.0	47.2
0.134	1	3.7	14.7	58.7
	2	1.0	15.3	65.3
	3	3.3	26.7	98.0
	Mean	2.7	18.9	74.0
0.376	1	3.7	22.0	83.7
	2	3.0	15.3	61.0
	3	3.3	18.7	70.3
	Mean	3.3	18.7	71.7
0.410	1	1.0	4.7	23.7
	2	1.0	8.0	33.7
	3	1.3	4.3	29.0
	Mean	1.1	5.7	28.8
1.201	1	0.3	0.7	1.0
	2	1.7	2.7	1.0
	3	0.3	1.7	1.7
	Mean	0.8	1.7	1.2
1.579	1	0.7	1.0	1.3
	2	1.3	1.7	0.3
	3	1.0	0.7	0.7
	Mean	1.0	1.1	0.8

Table 3 Effect values 

Exposure Period (hours)	ErCx value mg/L (95% confidence limits)			EyCxvalue mg/L (95% confidence limits)
	ErC10	ErC20	ErC50	EyC10	EyC20	EyC50
0 to 48	0.386 (0.382 - 0.392	0.395 (0.389 - 0.408)	0.663 (0.397 - 0.957)	0.381 (0.380 - 0.383)	0.386 (0.384 - 0.390)	0.401 (0.396 - 0.411)
0 to 72	0.394 (0.388 - 0.401)	0.422 (0.395 - 0.478)	0.731 (0.679 - 0.793)	0.382 (0.380 - 0.384)	0.388 (0.386 - 0.391)	0.406 (0.400 - 0.452)
NOEC (0-72h)	0.376 mg/L (Determined byBonferroni t Test)^$			0.410 mg/L (Determined by Bonferroni t Test)^$

Table 4: Validity criteria for OECD 201.

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control and solvent control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	77.2	yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control and solvent control cultures must not exceed 35%	19.08% (control) 47.56% (solvent control)*	see below
The coefficient of variation of average specific growth rates during the whole test period in replicate control and solvent control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	5.76%	yes

*These do not fulfil all the validity criteria of the study and the solvent control is not compliant with the OECD Guideline for Testing of Chemicals reference 201 Alga, Growth Inhibition Test 2011. Nevertheless, as the control replicates passed all validity criteria, the solvent control cell density and rate of growth was sufficient and EC50’sand NOEC/LOEC values were achieved, all effects been attributed the test material and statistical analysis has been conducted in comparison to the solvent control. The cell density in the control cultures increased by the required amount (a factor of at least 16) within the 72-hour test period. Also, there were no cell morphological abnormalities within the control units. Therefore, any changes in cell density in the test concentrations can be attributed to the test substance. In the opinion of the study director, this had no detrimental effect on the validity and integrity of this study.

 

Applicant's summary and conclusion

Conclusions:

For validity criteria please see Table 4 at "Any other information on results incl. tables"