Trimethyl orthoacetate

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:

2003-11-03 - 2003-11-06 (experimental phase)

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)

Version / remarks:

OECD Test Guideline 202 (I) „Daphnia sp., Acute Immobilisation Test" (1984)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

EU-Directive 92/69/EEC, C.2. „ Acute Toxicity for Daphnia" (1992)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: The test item was stored at ambient temperature.

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 1000, 700, 500, 350, 250 and 180 mg/L (nominal)
- Sampling method: The analytical verification of the test item concentrations was carried out for each of the two test batches after 0 and 24 hours (semistatic test procedure). For stability control the concentrations tested, were made up in the same way as the concentrations for biological part (in separate vessels without test organisms and NaHCO3), given in TOC test vials (5 ml each), closed with Parafilm and incubated under test conditions. Additionally, the concentration of the two stock solutions was determined after 0 h for each batch.
- Sample storage conditions before analysis: not specified

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: For the preparation of the stock solution 2.041 g/L of the test item were equilibrated in synthetic fresh water without NaHCO3. The resulting solution was used as stock solution. To minimize the loss of the volatile test item during the test, the vessels were closed tightly (gas tight septum).
- Controls: 1 control
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): not specified

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna STRAUS
- Strain/clone: clone 5
- Source: Originally, the animals were received 1991 from Dr. N. Caspers (Bayer AG, Leverkusen, Germany); subsequently they were bred in house.
- Age of parental stock (mean and range, SD): In-house breeding since 2007-09-27
- Husbandry: For breeding, the females are maintained in M4 medium in 1 L beakers. The daily amount of food, comprising Desmodesmus subspicatus, is such that the amount added is consumed by the animals. A reddish dark-brown coloration of the animals indicates that they are healthy.
At two to three day intervals, the exuviae are syphoned off and the water is changed. In the course of this, the offspring is removed from the breeding vessels.
At regular intervals of approximately 4 weeks, offspring is isolated from the vessels. They serve as a basis for further breeding.
- Feeding during test: none

ACCLIMATION
- Acclimation period: none
- Acclimation conditions (same as test or not): The same.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

no

Hardness:

14°dH = 250 mg CaCo3/L

Test temperature:

20.2 - 20.4 °C (mean: 20.3 °C)

pH:

7.8 - 8.3 oin the freshly prepared media
7.6 - 7.9 in the aged media

Dissolved oxygen:

8.6 - 8.9 in the freshly prepared media
8.4 - 8.8 in the aged media

Nominal and measured concentrations:

nominal: 1000, 700, 500, 350, 250 and 180 mg/L
measured in freshly prepared media (1st and 2nd batch): 1088 and 1091, 698 and 806, 453 and 539, 383 and 403, 256 and 268, 182 and 214 mg/L
measured in aged media (1st and 2nd batch): 975 and 1028, 745 and 782, 504 and 543, 331 and 403, 266 and 268, 166 and 194 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 12 ml head-space test tubes with 10 ml content
- Type (delete if not applicable): closed (gas tight septum)
- Aeration: none
- Renewal rate of test solution (frequency/flow rate): semistatic test procedure (After 24 h test organisms were given in fresh test medium.)
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic fresh water
CaCI2 x 2 H20: 294 mg/l
MgS04 x 6 H20:114 mg/l
NaHC03: 65 mg/l
KCI: 6 mg/l
sum of Ca2+- and Mg2+-ions: 2.5 mmol
proportion of Ca2+-: Mg2+-ions (mol): 4:1
proportion of Na+-: K+-ions (mol): 10:1
Water hardness: 14°dH = 250 mg CaCO3/L
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: The test was conducted in the dark.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilisation after 24 and 48h of exposure.

VEHICLE CONTROL PERFORMED: no

Reference substance (positive control):

yes

Remarks:

Potassium dichromate is tested as reference item quarterly. Potassium dlchromate was investigated as reference item on September 3, 2003.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

other: main component (98%)

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

other: main component (98%)

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

700 mg/L

Nominal / measured:

nominal

Conc. based on:

other: main component (98%)

Basis for effect:

mobility

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: Limit values after 24 h exposition: 1 mg K2 Cr2 O7 / L < 50 % effect ( 50 % effect (>/= EC 50)
- ECx: 1 mg K2 Cr2 O7 / L = 20 % effect (= EC 20), 2 mg K2 Cr2 O7 / L = 100 % effect (= EC 100)
The results demonstrate that the sensitivity of the individuals lies In the normal range.

Validity criteria fulfilled:

yes

Conclusions:

The study was performed according to OECD TG 202 without deviations which may have impact on the validity of the study. Thus, the results were obtained via a scientifically reasonable method. Hence, there is no doubt that the obtained results are not reliable.
Under the conditions used for the test, there was a significant immobilisation of the daphnia at concentrations >700 mg/L (definitive main test).
As a conclusion of the analytical part of this study, it can be stated that the concentrations of the test item remained sufficiently stable during incubation, by the performance of a semi-static test. Based on this, the reported effect concentrations should refer to the nominal concentrations tested. Accordingly, the EC50 after 48 hours was determined to be > 1000 mg/L.
Based on these results, the test item does not need to be classified as acute or chronic toxic to the aquatic environment.

Executive summary:

Trimethyl orthoacetate (TMOA) was tested for acute toxicity towards daphnia according to OECD-Test Guideline 202 (1984) in compliance with GLP. In order to investigate the influence of the test item towards the daphnia, the swimming behaviour of the animals was recorded. Under the conditions used for the test, there was a significant immobilisation of the daphnia at concentrations > 700 mg/L. As a conclusion of the analytical part of this study, it can be stated, that the concentrations of Trimethyl orthoacetate (TMOA) remained sufficiently stable during incubation, by the performance of a semi-static test. As a result of the supporting analysis it can be stated that the results of the biological part should be based on the nominal concentrations applied because the recoveries of the nominal concentrations were all >80%.

Description of key information

Short-term toxicity to aquatic invertebrates: EC50 (48 h) > 1000 mg/L, NOEC (48 h) = 700 mg/L for Daphnia magna based on immobilisation (OECD TG 202 and EU method C.2, GLP, semi-static)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 000 mg/L