Dibutylamine

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP guideline study; study report available

Data source

Reference

Reference 1

Reference Type:

other: J-CHECK

Title:

Unnamed

Year:

2020

Report date:

2020

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

2000

Report date:

2000

Reference 3

Reference Type:

other: recalculation

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

1984

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Diethylamine

EC Number:

203-716-3

EC Name:

Diethylamine

Cas Number:

109-89-7

Molecular formula:

C4H11N

IUPAC Name:

N-ethylethanamine

Test material form:

liquid

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot number of test material: B34683L
- Purity test date: >= 99%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature, in the dark
- Stability under storage conditions: Infrared absorption spectrum, NMR spectrum measurement and high-performance liquid chromatograph analysis were performed on the obtained test substance, and it was confirmed that no contradiction was found with the structure of the test substance and the purity was confirmed. At the end of the test, the same measurement and analysis was performed, and when compared with the measurement and analysis results before the start of the test, no difference was found. Therefore, it was determined that the test substance was stable during storage in the sample storage in the research department.

OTHER SPECIFICS
- appearance: colorless, transparent liquid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

At the start of exposure:
- 0.5 mL of test solution from each test container were collected and filled into a vial.
- 500 μL 2,4-Dinitrofluorobenzene (100 mmoL acetonitrile solution) and 100 μL sodium hydroxide (0.1N) were added and the solution was left at room temperature for 30 minutes or more to UV label the test substance.
- The samples were than analysed in an HPLC autosampler.
At the end of exposure:
- 1.0 - 2.0 mL of test solution from each test container were collected, centrifuged and the supernatant was filled into a vial.
- 500 μL 2,4-Dinitrofluorobenzene (100 mmoL acetonitrile solution) and 100 μL sodium hydroxide (0.1N) were added and the solution was left at room temperature for 30 minutes or more to UV label the test substance.
- The samples were than analysed in an HPLC autosampler.

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name:
- Strain: ATCC 22662
- Source (laboratory, culture collection): obtained from American Type Culture Collection

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: no deformation or abnormal cells were observed

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

23 +-2 °C
measured temperature in the incubation chamber: 22.0 °C (0h), 22.8 °C (24 h), 23.0 °C (48 h), 23.1 °C (72 h); 22.7 °C (average)

pH:

pH values measured in
Control: 7.4 (0h), 7.2 (72h)
Treatments: 7.4 - 10.0 (0h), 7.4 - 8.2 (72h)
For details see 'Any other information on results incl. tables'

Nominal and measured concentrations:

nominal: 4.8, 8.6, 15.4, 27.8, 50.0 and 90.0 mg/L
measured: 0 h: 4.0, 7.4, 14.8, 26.8, 45.3 and 87.3 mg/L (83.3 to 97.0% of nominal)
72 h: 2.1, 4.1, 7.5, 13.3, 24.0 and 46.0 mg/L (43.8 to 51.1% of nominal)
Therefore the geomean concentrations were used to recalculate the ECx values (BASF SE, 2020)
Geomean concentrations: 2.9, 5.5, 10.5, 18.9, 33.0 and 63.4 mg/L

Details on test conditions:

TEST SYSTEM
- Fill volume: 100 mL
- Aeration: no
- Initial cells density: 1*10^4 cells/ml
- Control end cells density: 194.6*10^4 cells/ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: standard medium (OECD medium)

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: 24 h
- Light intensity and quality: 4000 - 5000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : cell density: measured daily; pH values of the test solutions: measured at the beginning and at the end of the test; temperature and light intensity: measured daily

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

34.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 32.0 - 36.3 mg/L

Remarks:

recalculated with ToxRat v3.3

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

50.9 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 49.3 - 52.4 mg/L

Remarks:

recalculated with ToxRat v3.3

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

11 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

result from JCHECK, NITE homepage; June 2019

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

54 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

result from JCHECK, NITE homepage, June 2019

Effect concentrations 5

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

result from study report; sectional growth rate (24 - 72h)

Effect concentrations 6

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

75.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 69.5 - 82.5 mg/L

Remarks:

result from study report; sectional growth rate (24 - 72h)

Results with reference substance (positive control):

- 72-h EbC50: 0.52 mg/L

Any other information on results incl. tables

The data of the original report were re-evaluated using ToxRat v3.3 in order to obtain an EC10, which is originally not reported. According to REACH Guidance document chapter R.10 Table R.10-1 (Overview of toxicity test endpoints and guidance on derivation of L(E)C50 and NOEC values) an EC10 for a long-term test which is obtained using an appropriate statistical method (usually regression analysis) will be used preferentially.

There has been a recommendation within OECD in 1996 to phase out the use of the NOEC, in particular as it can correspond to large and potentially biologically important magnitudes of effect. The advantage of regression method for the estimation of ECx is that information from the whole concentration-effect relationship is taken into account and that confidence intervals can be calculated. These methods result in an ECx, where x is a low effect percentile (e.g. 5-20%). It makes results from different experiments more comparable than NOECs.  For the re-evaluation, geomean concentrations were calculated.

Result tables from original study report

Table 1: Measured concentrations of Diethylamine during a 72 -h exposure of Selenastrum capricornutum with calculated geomean concentrations (added by BASF SE, 2020)

Nominal concentration [mg/L]	Measured concentration – 0 h (% of nominal) [mg/L]	Measured concentration – 72 h (% of nominal) [mg/L]	Geomean Concentration [mg/L]
Control	< 0.04	< 0.04	0
4.8	4.0 (83.3)	2.1 (43.8)	2.9
8.6	7.4 (86.0)	4.1 (47.7)	5.5
15.4	14.8 (96.1)	7.5 (48.7)	10.5
27.8	26.8 (96.4)	13.3 (47.8)	18.9
50.0	45.3 (90.6)	24.0 (48.0)	33.0
90.0	87.3 (97.0)	46.0 (51.1)	63.4

Table 2: Cell densitiy of Selenastrum capricornutum

Nominal concentration [mg/L]	No.	Cell Density (a) – 0 h	Cell Density (a) – 24 h	Cell Density (a) – 48 h	Cell Density (a) – 72h
Control	1	1.0	5.8	38.7	193.3
	2	1.0	5.3	41.8	198.2
	3	1.0	6.1	39.6	192.4
	Average	1.0	5.7	40.0	194.6
	S.D.	0.0	0.41	1.59	3.09
4.8	1	1.0	4.9	34.4	179.7
	2	1.0	4.6	38.2	190.5
	3	1.0	5.5	39.2	202.8
	Average	1.0	5.0	37.3	191.0
	S.D.	0.0	0.49	2.52	11.54
8.6	1	1.0	5.1	36.5	198.6
	2	1.0	5.4	38.2	189.6
	3	1.0	5.7	37.8	184.4
	Average	1.0	5.4	37.5	190.9
	S.D.	0.0	0.28	0.86	7.20
15.4	1	1.0	5.4	36.3	200.0
	2	1.0	5.2	35.4	188.4
	3	1.0	4.9	35.3	182.4
	Average	1.0	5.2	35.7	190.3
	S.D.	0.0	0.24	0.55	8.94
27.8	1	1.0	4.7	39.6	152.2
	2	1.0	5.6	38.7	147.1
	3	1.0	4.9	37.8	146.1
	Average	1.0	5.0	38.7	148.5
	S.D.	0.0	0.46	0.91	3.26
50.0	1	1.0	4.1	28.4	129.4
	2	1.0	3.8	29.9	132.9
	3	1.0	3.8	30.1	124.4
	Average	1.0	3.9	29.5	128.9
	S.D.	0.0	0.21	0.89	4.24
90.0	1	1.0	1.5	3.1	4.0
	2	1.0	1.5	2.6	2.8
	3	1.0	1.9	3.1	3.8
	Average	1.0	1.6	2.9	3.5
	S.D.	0.0	0.23	0.30	0.65

Each value represents the mean of three sample counts

(a) Cell density x 10^4 cells/ml)

Table 3: pH values at 0 -hour and 72 -hour exposure

Nominal concentration [mg/L]	pH – 0 h	pH – 72 h
Control	7.4	7.2
4.8	7.4	7.4
8.6	7.5	7.5
15.4	7.7	7.7
27.8	8.3	7.8
50.0	9.4	8.0
90.0	10.0	8.2