Registration Dossier

Ecotoxicological information

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:
05.12.1988 - 08.12.1988
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study (OECD 201), no concentration was analytically verified

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1988
Report Date:
1988

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Dimethyl sulphate
- Physical state: liquid
- no further details stated
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not applicable

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
no data

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- detailed describtion is included in the study report
- Controls: yes
- no further significant details stated

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Green alga
- Source (laboratory, culture collection): own culture; an algal strain of S. subspicatus CHODAT was obtained as a monospecific, axenic culture labelled strain86.81 SAG from the Collection of Algal Cultures, University of Göttingen

- no further significant details stated

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
no data

Test conditions

Hardness:
no data
Test temperature:
test flasks were placed in a water bath of 25 +/- 2 °C
pH:
pH 6.1 - 8.4
Dissolved oxygen:
no data
Salinity:
The medium was used as stated in the OECD guideline 201 (2006) with one differentiation:
OECD medium:
FeCl3·6(H2O): except of using 0.0640 mg/L, 0.08 mg/L was used
Nominal and measured concentrations:
- based on a range finding study
- nominal: 10, 18, 32, 56, and 100 mg/L
Details on test conditions:
- test procedure followed the guidelines of OECD No. 201
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 300 ml Erlenmeyer flasks, filled with 100 ml medium and closed with cotton stoppers.
- Aeration: flasks were placed on a electric shaker with a constant motion of 100 cycles/minute


TEST MEDIUM / WATER PARAMETERS
- test substance was dissolved in nutrient medium
- nutrient medium was prepared freshly for each use
- Source/preparation of dilution water: reagent grade water; medium preparation is described in study report


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: cultures were iluminated constantly using white spectrum fluorescent lamps and a light intensity of ca. 4000 lux
- Light intensity and quality: universal white type fluorescent lamps, 4000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]: at test day 1, 2 and 3 the cell concentrations were determinded for each flask; 5 ml test medium were sampled in a test-tube rack (detailed description of method in study report)
- Other: pH values and temperature was measured at the same as the cell concentrations

- no further significant details stated

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
46.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % confidence limit
Duration:
72 h
Dose descriptor:
EC0
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
no positive control was measured
Reported statistics and error estimates:
At the end of testing the growth curves and the concnetration-effect relationsship were plotted using a computer program (SigmaPlotTM, Vers. 3.1; Jandel Scientific).

Any other information on results incl. tables

Table 3: Cell concentration per mL x 10^4

Concentration

Mean values

(mg/L)

Flask No.

Cell concentration per mL x 10^4

Evaluation times

24 hours

48 hours

72 hours

Untreated control

1-6

3.6

13.4

42.4

10

7-9

3.1

13.2

42.3

18

10-12

3.4

10.7

39.3

32

13-15

2.0

8.9

33.2

56

16-18

1.9

6.7

17.4

100

19-21

1.7

3.9

5.3

Table 4: Growth inhibition when compared with control

Concentration (mg/L)

Inhibition after 72 hours

10

1.9 %

18

12.3 %

32

29.8 %

56

58.7 %

100

84.1 %

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The EC50 (growth rate) was calculated at 46.9 mg/L for the algae species scenedesmus subspicatus CHODAT.
Executive summary:

No analytical verification was performed, due to this the EC50 based on nominal concentrations. But due to the fact that DMS hydrolyses very fast (DT50 <1d) in water to monomethyl sulfate and methanol, the inhibition was predominantly due to the toxicity of the hydrolysis products.