2,2'-[1,2-ethanediylbis(oxy)]bis(ethanethiol)

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Not reported.

Vehicle:

no

Details on test solutions:

The test item is very soluble and a stock solution of 100 mg/L was easily prepared on the day of the start of the trial.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea (Daphnia magna Straus)
- Strain/clone: Clone 5
- Bred in Elendt M7 and fed with Raphidocelis subcapitata
- Selection of test organisms (< 24h) by sieving
- Feeding during test: None

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

None.

Post exposure observation period:

No post-exposure observation.

Hardness:

Not measured.

Test temperature:

19.5-20.5°C (min-max, as measured in the experimental room)

pH:

7.9-8.2 (min-max)

Dissolved oxygen:

8.5-9.2 mg/L (min-max)

Salinity:

Freshwater

Conductivity:

Not measured.

Nominal and measured concentrations:

Nominal: 0 ; 0.1 ; 0.2 ; 0.4 ; 0.8 ; 1.6 ; 3.1 ; 6.25 ; 12.5 ; 25 ; 50 ; 100 mg/L
Measured at 0h: Measured at 72h:
The four highest concentrations did not deviate by more than 20% from the initial measured concentrations. LD was 6.4 mg/L and it was therefore not surprising that expected concentrations close to or lower than 6.4 mg/L could not be detected. All in all, it was considered reasonable to use nominal concentrations to calculate the adverse effects of DMDO on Daphnia in this study.

Details on test conditions:

TEST SYSTEM
- Test vessel: 120 mL flask closely tight with aluminium caps equipped with PTFE septa.
- Renewal: static test, no headspace.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS: as described in ISO 6341 standard

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: Darkness
- Light intensity: Not measured

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : immobility as defined in the OECD 202 guideline.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.76 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Details on results:

Immobility of the daphnids is presented in table 1. 48h-EC50 was 0.76 mg/L

Results with reference substance (positive control):

24h-EC50 with potassium dichromate was 0.85 mg/L for mobility.

Reported statistics and error estimates:

Statistical analysis in the report was found to be erroneous. Reanalysis of the data was performed with ToxRat 3.2.2 software. The statistical output is attached to the RSS.

Table 1: Immobilisation of Daphnia magna in response to graded concentrations of DMDO (mg/L).

	IMMOBILITY
Nominal concentration	Flask 1	Flask 2	Flask 3	Flask 4	Total	% Immob.
Control	0	0	0	0	0	0
0.1	0	0	0	0	0	0
0.2	1	0	0	0	1	5
0.4	1	1	0	0	2	10
0.8	2	1	0	0	3	15
1.6	3	1	1	1	6	30
3.1	1	0	0	0	0	5
6.3	1	1	1	0	3	15
12.5	4	1	1	1	7	35
25	3	2	1	1	7	35
50	5	4	3	2	14	70
100	5	5	4	3	17	85

Validity criteria fulfilled:

yes

Conclusions:

48h-EC50 was 0.76 mg/L.

Executive summary:

The acute toxicity (inhibition of mobility) of dimercapto-1,8 -dioxa-3,6 -octane (DMDO) for Daphnia magna was assessed according to the method C2 of the European Directive 92/69/CEE. The study was carried out in compliance with the Principles of OECD Good Laboratory Practices.

Daphnia were exposed in a static test to a concentration range of 0.1 to 100 mg/L DMDO (spacing factor 2). The test was performed with 5 daphnids per vessel. Since DMDO is volatile, the test was performed using closed flasks as test glassware. In order to avoid volatilisation of DMDO, flasks were entirely filled with test solutions and closed with butyl rubber caps covered with PTFE.

For each exposure concentration, the percentage of immobilisation at 24 hours and 48 hours was recorded. The test concentrations of DMDO were measured by GC. 48h-EC50 was 0.76 mg/L. All validity criteria were fulfilled.

Description of key information

The acute toxicity (inhibition of mobility) of dimercapto-1,8 -dioxa-3,6 -octane (DMDO) for Daphnia magna was assessed according to the method C2 of the European Directive 92/69/CEE. The study was carried out in compliance with the Principles of OECD Good Laboratory Practices.

Daphnia were exposed in a static test to a concentration range of 0.1 to 100 mg/L DMDO (spacing factor 2). The test was performed with 5 daphnids per vessel. Since DMDO is volatile, the test was performed using closed flasks as test glassware. In order to avoid volatilisation of DMDO, flasks were entirely filled with test solutions and closed with butyl rubber caps covered with PTFE.

For each exposure concentration, the percentage of immobilisation at 24 hours and 48 hours was recorded. The test concentrations of DMDO were measured by GC. 48h-EC50 was 0.76 mg/L. All validity criteria were fulfilled.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.76 mg/L