diethylmethoxyborane

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with good documentation. The test substance is unstable in the test medium and the results show that hydrolysis probably occured during the test. However, no analytical measurements are available.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

425-380-9

EC Name:

-

Cas Number:

7397-46-8

Molecular formula:

C5H13BO

IUPAC Name:

methyl diethylborinate

Details on test material:

- Name of test material (as cited in study report): DEMB
- Physical state: liquid
- Analytical purity: 99.4%
- Stability under test conditions: No, hydrolyses slowly
- Storage condition of test material: At room temperature in the dark

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The test substance was weighed in methanol at a ratio of 1:1. This solution was stored in a deep freeze for ca. 4 days before the start of the preparation of the test solutions. Preparation of the test solutions started with preparation of a range of stock solutions in methanol. After thorough mixing, volumes of 0.01 mL per 100 mL were taken from each stock and added to ISO-medium. After preparation, volumes of 50 mL were added to each replicate of the respective test concentration. Subsequently, a volume of < 0.4 mL of an algal suspension was added to each replicate providing a cell density of 10000 cells/mL.

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: CCAP 278/4
- Stock culture: Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light (4000-9000 lux) in a climate room at a temperature of 23 ± 2 °C.

ACCLIMATION
- Acclimation period: preculture 4 days before the start of the test
- Culturing media and conditions (same as test or not): same as test

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

24 mg/L CaCO3

Test temperature:

22.5 - 23 °C

pH:

8.2 - 8.4

Nominal and measured concentrations:

1.0, 2.2, 4.0, 6.4, 10, 16, 32, 56 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL, all-glass
- Initial cells density: 20000 cells/mL
- Control end cells density: 2063000 cells/mL (solvent control)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 1

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water purified by reverse osmosis and then passed over activated carbon and ion-exchange cartridges (Millipore Corp., Bedford, Mass., USA).
- Intervals of water quality measurement: temperature daily, pH at the start and at the end of the test

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Photoperiod: continuous illumination
- Light intensity and quality: TLD-lamps of 18 Watt (Philips, Spain) yielding 7500 - 8500 lux.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber, daily

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.1, 1, 10 and 100 mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

190 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

42 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

22 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 18 - 27 mg/L

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

6.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 4.0 - 8.0 mg/L

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 10 -15 mg/L

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

6.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 7

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

6.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Analytical support was not available as detection of the concentrations tested was not possible with any of the analytical methods available. Hence, no sampling for analysis was performed.
- EC50 for growth rate reduction increased from 42 mg/L to 190 mg/L, likely due to slow hydrolysis of DEMB.

Results with reference substance (positive control):

The 72-hour EC50 for growth inhibition (EbC50: 0 - 72h) was 1.0 mg/L
The 72-hour EC50 for growth rate reduction (ErC50: 0 - 72h) was 1.6 mg/L