1,3-dimethylurea

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: Guideline study with acceptable restrictions

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

Reference 2

Reference Type:

other: recalculation

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: DIN 38412, part 9

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,3-dimethylurea

EC Number:

202-498-7

EC Name:

1,3-dimethylurea

Cas Number:

96-31-1

Molecular formula:

C3H8N2O

IUPAC Name:

1,3-dimethylurea

Details on test material:

- Name of test material (as cited in study report): Dimethylharnstoff (1,3-dimethylurea)
- Analytical purity: no data given

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Scenedesmus subspicatus CHODAT
- Strain: SAG 86.81
- Source: Algae collection, University of Goettingen, Germany

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

20 °C

pH:

8.5 - 8.6

Nominal and measured concentrations:

Nominal test concentrations (mg/l):
0 (Control)
31.25
62.5
125
250
500

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Fill volume: 10 ml
- Aeration: none
- Renewal rate of test solution (frequency/flow rate): none
- Initial cells density: 10000 cells/ml
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 2


GROWTH MEDIUM
- Standard medium used: according to OECD medium


TEST MEDIUM / WATER PARAMETERS
- Preparation of the medium: The test medium of the highest test concentration, 500 mg/l (nominal) was prepared. Following this, serial dilutions of this test medium were prepared in order to obtain the desired test concentrations. Stock solution: 1000 mg/l


OTHER TEST CONDITIONS
- Photoperiod: permanent illumination
- Light intensity and quality: artificial light - light intensity: 50 - 200 uE at a wave length of 400 - 700 nm


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: At 0, 24, 48, 72, and 96 hours after test start, the algae cell density was determined by spectro-fluorometrical measurement using an impulse fluorometer. The parameters pH and temperature were determined at the end of the test. Also, at the end of the incubation period the algae cells were analyzed for signs of photosynthesis blockage by means of a spectrophotometrical scan at 300 - 780 nm.
- Chlorophyll measurement: spontaneous chlorophyll-A fluorescence at 685 nm as criterion for biomass (excitation with short light impulse at 435 nm). Measurements at 0, 24, 48, and 72 hours.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

125 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

250 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

288.3 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Remarks on result:

other: 187 - 387 mg/l 95% CL

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

678.53 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Remarks on result:

other: 484 - 1592 mg/l 95% CL

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 500 mg/L

Remarks on result:

other: not determined due to mathematical reasons

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

62.5 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Effect concentrations 7

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

125 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Effect concentrations 8

Duration:

72 h

Dose descriptor:

EC0

Effect conc.:

99 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Remarks:

integral

Remarks on result:

other: 36 - 150 mg/l 95% CL

Effect concentrations 9

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

193 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Remarks:

integral

Remarks on result:

other: 115 - 258 mg/l 95% CL

Effect concentrations 10

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

688 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Remarks:

integral

Remarks on result:

other: 479 - 1555 mg/l 95% CL

Details on results:

Yield 72 h
EyC10: 51 (27 - 74 95% CL) mg/l
EyC20: 117 (83 - 146 95% CL) mg/l
EyC50: 580 (479 - 775 95% CL) mg/l

LOEyC: 125 mg/l
NOEyC: 62.5 mg/l

Original effect values as given in the report:
(nominal concentrations):

72 h-EC20 = 121.5 mg/l

Reported statistics and error estimates:

Linear regression analysis