Dimethyl sulphate

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

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dimethyl sulphate

EC Number:

201-058-1

EC Name:

Dimethyl sulphate

Cas Number:

77-78-1

Molecular formula:

C2H6O4S

IUPAC Name:

dimethyl sulfate

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 concentrations

Effect concentrations 1

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

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC0

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

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.