Propanoic acid, 2-[(ethoxythioxomethyl)thio]-, methyl ester

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:

from 19 september 2000 to 19 july 2001

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:

yes

Remarks:

see below

Principles of method if other than guideline:

- The stock solutions were prepared in Tertiary butyl alcohol and not in DSWLE or ultrapure water. The test media of 18 and 32 mg/l were prepared by dosing 0.18 and 0.32 ml of stock solution in one litre of dilution water. This is above 0.10 ml as recommended in the guideline.
- According the information obtained from the sponsor the solubility of the test substance in water was 351 mg.!1
- The Department of Environmental Toxicology, part of TNO Nutrition and Food Research, has decided to issue reports and protocols under the name of 'TNO Chemistry'.
These deviations are assumed not to have affected the results of the study.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The actual concentrations of Rhodixan A-1 in the exposure media were determined by chemical analysis. Samples of the solvent control and the exposure media of 1.0, 5.6 and 32 mg/l were taken at t = 0h (newly prepared media). At t = 24h samples were taken from the 32 mg/l spent medium, because all test animals were immobile at that time. At t = 48h the spent solvent control and the 1.0 and 5.6 mg/l media were sampled again. Samples of ca. 30 ml were taken in 40 ml glass vials and transferred to the analytical laboratories of the Department of Residue Analysis for chemical analysis.

Vehicle:

yes

Remarks:

Tertiary Butyl Alcohol (TBA)

Details on test solutions:

DSWL-E was used as a control medium. Tertiary butyl alcohol (TBA) was used as a carrier to dose the test substance. The 1.0, 1.8, 3.2, 5.6 and 10 mg/l solutions were prepared by dosing 0.1 ml of stock solution in 1 litre of dilution water. The 18 mg/l and 32 mg/l were prepared by dosing 0.18 ml and 0.32 ml respectively. A solution of 0.32 ml stock solution TBA per litre of dilution water was used as a solvent control.

Test organisms (species):

Daphnia magna

Details on test organisms:

- Common name: Daphnia Magna
- Strain/clone: No data
- Source: no data available
- Daphnia magna has been cultured in the dilution water, used for the test. Every week a number of cultures is started with ca. 125 Daphnias of the same age (about one day) inca. 4 litres of dilution water. The cultures are fed daily with ca. 4 x 109 algal cells (Chlorella) and ca. 0.13 grams of yeast per 4 litre. The medium is completely replaced at least once a week; at the same time ail young born are removed. The cultures are kept at 20 ± 1 °C under a 16h light and 8h dark regime with transition periods of ca. 30 minutes. After 4 weeks the cultures are discarded.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

no

Hardness:

no data

Test temperature:

20.0 - 20.5°C

pH:

8.1 - 8.3

Dissolved oxygen:

8.2 mg O2/l

Salinity:

no data

Conductivity:

no data

Nominal and measured concentrations:

The nominal concentrations tested were 1.0, 1.8, 3.2, 5.6, 10, 18 and 32 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 150 ml ail-glass beakers, each containing 100 ml of exposure medium
- Aeration: the exposure media were not aerated or replaced.
- Type of flow-through (e.g. peristaltic or proportional diluter): no data
- Renewal rate of test solution (frequency/flow rate): no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): no data
- No. of vessels per vehicle control (replicates): 4
- Biomass loading rate: no data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The dilution water used was DSWL-E prepared from ground water.
- Total organic carbon: 2.3 mg/l
- Particulate matter: no data
- Metals: no data
- Pesticides: no data
- Chlorine: no data
- Alkalinity: no data
- Ca/mg ratio: no data
- Conductivity: no data
- Salinity: no data
- Culture medium different from test medium: DSWL-E was used as a control medium. Tertiary butyl alcohol (TBA) was used as a carrier to dose the test substance.
- Intervals of water quality measurement: no data

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod:16 h light/8 h dark regime with transition periods of ca. 30 minutes in a temperature controlled room.
- Light intensity: no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The mobile and if applicable the immobile animals were counted after 24 hours and at the end of the test according to the definition given in the OECD Guideline no. 202 (animals notable to swim within 15 seconds after gentle agitation of the test containers are considered to be immobile). At the same time the condition (swimming behaviour, colour or any other visually observable morphological or behavioural criterion) of the mobile animals was compared with that of the control animals. The condition of the Daphnias from the exposure media of 3.2, 5.6, 10, 18 and 32 mg/l was also checked under a microscope at the end of the test.
The effect of a test substance on the mobility of animals can be expressed by a quantity denoted as the EC50 (= Effective Concentration, 50%), i.e. the exposure concentration of the substance which would immobilize 50% of an infinite population of the exposed animals. The EC50 is qualified according to the duration of exposure.
The effect of a test substance on the mobility of animals can also be expressed by a quantity denoted as the EC100 (= Effective Concentration, 100%), i.e. the lowest exposure concentration of the substance which immobilizes 100% of the exposed animals. The EC100 is qualified according to the duration of the exposure.
The 'No Observed ;Effect Concentrations' (NOEC values) are the highest concentrations tested showing no effect throughout the exposure time. The NOEC values are qualified according to the duration of exposure and are estimated by comparing effects with regard to mobility and condition of the exposed animals with those of the control animals.

VEHICLE CONTROL PERFORMED: yes

RANGE-FINDING STUDY
- Test concentrations: no information
- Results used to determine the conditions for the definitive study: no data

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

5.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

3.8 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

All media were completely clear (visually assessed) throughout the test.
There were no immobile animals in the control medium at the end of the test. The animals in the test vessel containing 10 mg/L appeared to have an oily substance on their bodies.
At 10, 18 and 32 mg/l all test animals were immobile at the end of the test; at 5.6 and 3.2 mg/l a part of the animals was immobile and the condition of the animals was less than that of the control animals. At 1.8 mg/l all animals were mobile, only one animal showed a slower swimming behaviour. As this phenomenon (one single slow swimming animal) also occurred in the dilution water control, this is not taken into account to estimate the NOEC for condition. The NOEC values for mobility and condition are therefore both 1.8 mg/l respectively.

Results with reference substance (positive control):

no data

Reported statistics and error estimates:

no data

Validity criteria fulfilled:

yes

Remarks:

There was no immobility in the control vessels. The dissolved oxygen concentration was above 5.4 mg/l (>= 60% of the air saturation value at 20°C).

Conclusions:

At 1.8 mg/l nominal concentration no immobilisation was observed. Based on the average percentage of the test substance present during the test, the 48h-NOEC was estimated to be 1.3 mg/l and the 48h-EC50 is calculated to be 3.8 mg/l measured concentrations. The Rhodixan A-1 is considered as toxic to the aquatic organisms tested.

Executive summary:

Rhodixan A-1 has been tested for acute toxicity to daphnia magna. The study was carried out according to OECD guideline No.202 and Directive 67/548/EEC, Annexe V, test method C.2 and in compliance with Good Laboratory Practices.

 

The test was carried out under static conditions with 5 daphnias per vessels and four replicates for the control medium and each concentration. The exposure duration was 48 hours. Stock solutions in Tertiary Butyl Alcohol (TBA) containing the appropriate amounts of the test substance were used to obtain the following nominal concentrations : 1 – 1.8 – 3.2 – 5.6 – 10 – 18 – 32 mg/l.

    

The actual concentration of Rhodixan A-1 in the exposure media was determined by HPLC with UV-detection. Samples of the exposure media were taken at T=0h just after dosing, and also in the spent media at the end of the test. The average percentage of the test substance present during the test was 71%.

 

The validity criteria were fulfilled since no immobility was observed in the control vessel and the dissolved oxygen concentration was more than 60%. At 1.8 mg/l nominal concentration no immobilisation was observed. Based on the average percentage of the test substance present during the test, the 48h-NOEC was estimated to be 1.3 mg/l and the 48h-EC50 is calculated to be 3.8 mg/l measured concentrations. The Rhodixan A-1 is considered as toxic to the aquatic organisms tested.

Description of key information

At 1.8 mg/l nominal concentration no immobilisation was observed. Based on the average percentage of the test substance present during the test, the 48h-NOEC was estimated to be 1.3 mg/l and the 48h-EC50 is calculated to be 3.8 mg/l measured concentrations. The Rhodixan A-1 is considered as toxic to the aquatic organisms tested.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

3.8 mg/L

Additional information

A GLP-compliant study, scored as Klimisch 1 and flagged as a key study, is available on the Rhodixan A-1; giving a 48h-EC50: 3.8 mg/kg (measured concentrations) and revealing that the Rhodixan A-1 is toxic to Daphnia magna (TNO, 2001).