Trimethyl orthoacetate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

justification for analogue approach: see IUCLID section 13 "Read-across justification"

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: EPA-660/3-75-009, 1975

Principles of method if other than guideline:

Test procedures followed the basic flow-through test method described by the U. S. Environmental Protection Agency (EPA-660/3-75-009, 1975)

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

Water for all tests was untreated and obtained directly from Lake Superior and heated to mean test temperature.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: bluegill
- Source: Lake Mills Fish Hatchery, Lake Mills, WI, USA
- Weight at study initiation (mean and range, SD): Average weights of exposed fish were obtained by weighing control fish from each test. Average weight of bluegills was 3.07 ± 1.38 g

- Feeding during test: Fish were not fed 24 h before or during a test

- holding before 24 h before test: at respective test temperature and fed a commercial formulation of dry food.

Test type:

flow-through

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

46.6 mg/L CaCO3 (40.4 - 56.3)

Test temperature:

19.8 ± 2.3 °C

pH:

7.04 - 7.97

Dissolved oxygen:

78.8 % (54.3 - 88.9)

Nominal and measured concentrations:

five test concentrations and a control

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 530-L fiberglass holding tanks
- Type of flow-through (e.g. peristaltic or proportional diluter): The exposure system for fish consisted of several modified proportional diluters with dilution factors ranging from 0.6 to 0.8. Each diluter cycle delivered 1.0 L of water and toxicant, where appropriate, to each of five test concentrations and a control. Each test concentration and control was duplicated by dividing the original volume equally using flow-splitting tanks. The glass exposure tanks contained 6.3 L water. Diluters were cycled at a rate to yield 5 to 8 tank volumes/day.

- No. of organisms per vessel: 10

TEST MEDIUM / WATER PARAMETERS
- Alkalinity: 41.7 mg/L CaCO3 (30.0 - 46.0)
- Mean dissolved oxygen: 78.8 % (54.3 - 88.9)

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

15 400 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 13500-17600

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

12 700 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 11800-13700

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

16-05-2010 to 20-05-2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP-compliant study following equivalent of OECD 203. No analytical monitoring, limitations in reporting regarding test substance.

Justification for type of information:

justification for analogue approach: see IUCLID section 13 "Read-across justification"

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: SOP E257

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

not applicable

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data reported.

Analytical monitoring:

no

Details on sampling:

Observations were made at test initiation and at every subsequent 24 hours.

Vehicle:

no

Details on test solutions:

Solutions were clear and colourless to cloudy white liquids depending upon the concentration of test substance. Solutions were replaced every 24 hours.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

Supplier: Bibury Trout Farm, Bibury, Nr Cirencester, GL7 5NL. Arrival: 3-05-2005. Number received: 200. Mortality during acclimatisation after 48h settling period: 5%. Acclimatisation period: 3-05-2005 to 16-05-2005. Acclimatisation temperature: 14.5 to 15.5°C. Dissolved oxygen: >93% ASV. At test termination mean of 10 fish sampled: 53.1 mm length and 1.46g weight.

Test type:

semi-static

Water media type:

freshwater

Total exposure duration:

96 h

Post exposure observation period:

Preliminary test: 3 fish were tested in a static test for 96 hours in 2L aquariums at concentrations of 100 and 1000 mg/L. No mortality or abnormal behaviour was observed at either concentration. This lead to the definitive test having concentrations of 0 (control) and 1000 mg/L.

Hardness:

Dilution water: 300 mg CaCO3/L.

Test temperature:

14°C. Measurements were taken at test initiation and termination and before and after each renewal of solutions.

pH:

Measurements were taken at test initiation and termination and before and after each renewal of solutions. pH values ranged from 7.9 to 8.2 in the control and 7.9 to 8.4 for 1000 mg/L.

Dissolved oxygen:

Measurements were taken at test initiation and termination and before and after each renewal of solutions. Dissolved oxygen ranged from 100 to 96 % ASV in the control and 98 to 95% ASV in the 1000 mg/L concentration.

Salinity:

No data reported.

Nominal and measured concentrations:

After the preliminary test, concentrations of 0 (control) and 1000 mg/L were decided for the definitiv test.

Details on test conditions:

Fish were stored and tests completed in dechlorinated mains water. Test vessels: 12 litre aquariums each of which contained 7 trout. Photoperiod: 16h light and 8h dark.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7). Purity: 99.9% (minimum). Source: AnalaR. Chemex reference: ENV7315.060409.

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

300.82 mg/L

Nominal / measured:

nominal

Conc. based on:

other: acetate ion

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 300.82 mg/L

Nominal / measured:

nominal

Conc. based on:

other: acetate ion

Basis for effect:

mortality (fish)

Details on results:

No mortality was observed at 1000 mg/L concentration. No abnormal behaviour was observed. The LC50 was therefore calculated to be >1000 mg/L. The NOEC was 1000 mg/L. 1 mortality was observed in the control vessel (0 mg/L). No abnormal behaviour was observed. This mortality concentration was within the acceptable range for validation.
The NOEC and the LC50 were recalculated in order to report the effect concentrations based on the concentration of the acetate ion. The NOEC and LC50 were adjusted for the molecular weight of the acetate compared to the parent molecule and also the fact that the test substance is only 50% potassium acetate.

Results with reference substance (positive control):

At test termination, a sample of ten fish had a mean length of 61.4 mm and a mean weight of 2.07g. After 96h, the cumulative percent mortalities for200 mg/L were 57.1 and 100% for 400 mg/L concentration. In the 200 mg/L concentration, all fish showed abnormal behaviour from 48 hours. The LC50 value for 96 hours is therefore 190 mg/L, with 95% confidence intervals of 147 to 247 mg/L. The 96h NOEC is 100 mg/L and the LC100 is 400 mg/L.

Reported statistics and error estimates:

No data reported.

Validity criteria fulfilled:

yes

Conclusions:

The LC50 was calculated to be >300.82 mg/l based on the effect of the acetate ion.

Executive summary:

Beslagic (2005) is a GLP-compliant acute toxicity test on fish, following SOP E257 guidelines, which are modified from OECD 203. The study uses control and reference susbtances and showed no mortality at any concentration tested. No analytical monitoring was conducted and there are limitations in reporting regarding the test substance. The study is considered reliable and suitable for use for this endpoint.

The reported NOEC and LC50 were recalculated in order to report the effect concentrations based on the concentration of the acetate ion. The NOEC and LC50 were adjusted for the molecular weight of the acetate compared to the parent molecule and also the fact that the test substance is only 50% potassium acetate.

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Study period:

30.01.1995 to 03.02.1995

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP compliant, guideline study, acceptable with restrictions

Justification for type of information:

justification for analogue approach: see IUCLID section 13 "Read-across justification"

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data reported.

Analytical monitoring:

yes

Details on sampling:

Observations of mortality and obvious changes in appearance or behaviour were recorded after 3, 6, 24, 48, 72 and 96 hours. Dead fish were removed from the tank. Fish were assumed dead if there was no breathing movements or response light or mechanical stimulus.

Vehicle:

no

Details on test solutions:

Dilution water was reconstituted with the composition given in ISO/DIS 7346/1. The test substance was weighed, placed in a beaker and dilution water was added. The solution was homogenised by stirring with a glass rod and by Ultra-Turrax. No segragation or particlates were observed in the solutions.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

Source: own nursery at Hoechst AG. Hatched: 04.10.1994. Stocking date: 26.10.1994. Loading: <1 g fish /L water. The average length of the fish on 03.02.1995 was calculated from a sample of 7 to be 2.9 cm. 7 fish were used per experimental group. The fish were held for at least 14 days in dilution water prior to test initiation with a photoperiod: 12 hours daily. During acclimatisation, the fish were fed twice daily on Tetra Min, Tetra Works, Melle. The fish were not fed during testing.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

No data reported.

Hardness:

The total hardness of the dilution water was determined weekly and during the test was between 2.1 and 2.3 Ca2+ + Mg2+/L.

Test temperature:

The vessels were contained in a water bath thermostated at 22 +/- 1°C. Temperature: 21.7 to 22.6°C for both the concentration and the control group.

pH:

The pH measured before each renewal was 8.2. The pH of concentration group ranged from 7.8 to 8.0 and of control ranged from 8.1 to 8.2.

Dissolved oxygen:

The dilution water was aerated to oxygen saturation. During test, the oxygen content was > 80% of saturation value. Dissolved oxygen ranged from 7.0 to 9.6 mg/L for concentration group and 8.2 to 9.5 mg/L for control group.

Salinity:

No data reported.

Nominal and measured concentrations:

The concentrations were chosen because of the results of the preliminary test. Nominal concentration of 1000 mg/L and measured concentrations of 992.7 mg/L, meant that 99.3% of test substance was retained. All analyses were within the 10% of the target concentration.

Details on test conditions:

The static test was carried out in 10L glass containers (30cm long, 22cm wide, 24cm high) with a plexiglass lid. The containers were given a photoperiod of 12 hours, being lit from the top with an intensity of 700 lux. The containers were not ventilated during the experiment.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

300.82 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: acetate ion

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 300.82 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: acetate ion

Basis for effect:

mortality (fish)

Details on results:

There was no mortality in either the 1000 mg/l test group or the control substance, therefore the 96 hour LC50 is greater than 1000 mg/L. In the control group, all the fish were unchanged. For the first 24 hours, many of the fish in the concentration group showed changes in swimming, breathing or behaviour but after 24 hours, the behaviour of all the fish was normal.

The NOEC and the LC50 were recalculated in order to report the effect concentrations based on the concentration of the acetate ion. The NOEC and LC50 were adjusted for the molecular weight of the acetate compared to the parent molecule and also the fact that the test substance is only 50% potassium acetate.

Results with reference substance (positive control):

No data reported.

Reported statistics and error estimates:

Results cannot be precisely determined as only one concentration was used.

Validity criteria fulfilled:

yes

Conclusions:

There was no mortality in either the 1000 mg/l test group or the control substance, therefore the 96 hour LC50 is greater than 1000 mg/L.

Executive summary:

Zok (1995) is a GLP-compliant, acute toxicity to fish study following OECD guideline 203. Only one test concentration was used. The fish in the control study showed signs of abnormal behaviour for the first 24 hours, but not after this time. The study is considered reliable and suitable for use for this endpoint.

The reported NOEC and LC50 were recalculated in order to report the effect concentrations based on the concentration of the acetate ion. The NOEC and LOEC were adjusted for the molecular weight of the acetate compared to the parent molecule and also the fact that the test substance is only 50% potassium acetate.

Description of key information

Trimethyl orthoacetate is rapidly hydrolysed to methanol (CAS no. 67 -56 -1) and methyl acetate, which further hydrolyses to acetic acid (CAS no. 64 -19 -7) as final reaction product in the presence of water (< 2.4 h at pH 4, 7 and 9 at 50°C). Under neutral (pH 7) and acidic (pH 4) conditions, the half-life was < 1 h. The measured degradation of TMOA at pH 7 and 50°C correspond to a half-life time well below one day under normal outdoor conditions. Accordingly, reliable data of the hydrolysis products methanol and acetic acid are used to address the endpoint, which is entirely appropriate to draw conclusions on the toxicity of Trimethyl orthoacetate to fish.

1. Methanol

- Short term toxicity to fish: LC50 (96h) = 15400 mg/L for Lepomis macrochirus (OECD TG 203, flow-through)

2. Acetic acid

- Short term toxicity to fish: LC50 (96h) > 300.82 mg/L for Oncorhynchus mykiss based on the effect of the acetate ion (OECD TG 203, GLP, semi-static, without analytical monitoring)

- Short term toxicity to fish: LC50 (96 h) > 300.82 mg/L for Danio rerio based on the effect of the acetate ion (OECD 203, GLP, static)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

300.82 mg/L

Additional information

Concerning study data for acetic acid:

The studies by Beslagic (2005) and Zok (1995) are GLP compliant and follow standard guidelines. The test substance is only 50% potassium acetate.The remainder was predominantly water with no components likely to prejudice the study outcome in relation to assessing the activity of potassium acetate.The reported NOEC and LC50 were recalculated in order to report the effect concentrations based on the concentration of the acetate ion. The NOEC and LC50 were adjusted for the molecular weight of the acetate compared to the parent molecule and also the fact that the test substance is only 50% potassium acetate.