Methyl propionate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Investigations were carried out in order to determine the "no observed effect concentration" (NOEC) of 73 environmentally relevant substances in the 21 d Daphnia reproduction test. The test was conducted in line with the "Provisional Procedure: extended toxicology test with Daphnia magna (determination of NOEC for reproduction rate, mortality and the time of the first appearance of offspring; 21 d)" as of 1 January 1984, issued as the "Recommendation of the Federal Environmental Agency on the Performance of Testing according to Section 5, para 1 No. 3 of the Regulation on Application Documents and Evidence under the Chemicals Act" (Federal Environmental Agency).

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

Samples were taken twice from selected concentration levels of the test series during the test period and analysed chemically: the first sampling took place on one of the transfer days before the 7th day, i.e. in the period during which no offspring appeared; the second sampling took place between the 16th and 21st day.

Details on test solutions:

PREPARATION OF TEST SOLUTION
Before preparing the dilution series, the substances to be tested were fully dissolved (both quantitatively and optically) in dilution water using magnetic stirrers (stock solution = 16,000 mg/L). From the stock solution of the substance to be tested, graduated dilutions with dilution water were produced in the concentration range in which effects were to be expected in accordance with the results from the acute 24 h Daphnia test and a preliminary 3 d Daphnia test (same conditions as in the 21 d reproduction test). The dilution steps corresponded to a ratio of 1 : 2.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain/clone: Daphnia magna strain (IRCHA strain)
- Source: laboratory culture
- Feeding during test
- Food type: Tetramin-Hauptfutter (fish feed) and activated sludge were used as feeds
- Amount: the amount of feed given at that time was 2-3 times higher than the daily amount given in the open vessels (this led to an overall COD of 15-20 mg/L as the daily feed amount)
- Frequency: feeding took place on the days on which the parent animals were transferred

CULTURE CONDITIONS
For all Daphnia strain cultures, temperature-controlled, dechlorinated and oxygen-saturated tap water (German hardness 16°, pH value 7.6-7.7) was used which had been left to stand for 24 h. Before collecting the water, the tap was turned on fully and left to run for at least 1 h. All beakers were covered with watch glasses and placed on a white supporting surface. Feeding with dry algae of the Scenedesmus genus took place daily. The temperature of the culture area was regulated thermostatically at 20°C. Under exclusion of daylight, the area was lit by fluorescent lamps (Philips TL 65/33W) for 9 h between 7 a.m. and 4 p.m. On Monday and Thursday of each week the tap water in all beakers was renewed as were the beakers themselves on Mondays.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Test temperature:

The temperature of the test area was set thermostatically at 25 ± 1°C

Nominal and measured concentrations:

1.6 - 200 mg/L (dilution ratio 1:2)

Details on test conditions:

TEST SYSTEM
- Type: closed (bottles closed with groundglass stoppers)
- Fill volume: 250 mL
- Aeration: no
- Renewal rate of test solution: three times a week. The semi-static procedure adopted meant that the parent animals in the test and control vessels had to be pipetted 3 times a week (Mondays, Wednesdays and Fridays) into freshly prepared test and control media- in each case at the corresponding concentration level.
- 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: an artificial medium (synthetic fresh water) (DIN-German Institute of Standardisation, 1982a, b) of the following composition was used in the test and control
preparations:
11.76 g CaCl2.2H20 (A.R.)/1 litre deionised water
4.93 g MgSO4.7H20 (A.R.)/1 litre deionised water
2.59 g NaHCO3 (A.R.)/1 litre deionised water
0.23 g KCl (A.R.)/1 litre deionised water.
Twenty-five millilitres of each solution was pipetted into a graduated flask and completed to 1 litre with deionised water. The amount of calcium and magnesium ions in this solution was 2.5mmol/L. The molar relationship of sodium to potassium ions was 10:1. This water was aerated up to the water saturation level and the pH value was measured (8.0 ± 0.2). When using deionised water with a conductivity of < 1 µS/cm, the dilution water was diluted with 10% tap water.
- Culture medium different from test medium: yes (culture medium was dechlorinated and oxygen-saturated tap water)
- Intervals of water quality measurement: the pH value and the oxygen concentration were measured in two test vessels per concentration level three times a week (Mondays, Wednesdays and Fridays)

OTHER TEST CONDITIONS
- Photoperiod: The test culture area was protected from daylight and lit from 7 a.m. to 4 p.m. with fluorescent lamps--Philips TL 40/25W.

EFFECT PARAMETERS MEASURED
The test and control preparations were observed daily in order inter alia, to record the day on which the first offspring appeared. On Mondays, Wednesdays and Fridays (during test media renewal), dead parent animals or those incapable of swimming were removed. The offspring were counted and the total number for each test vessel was recorded.

TEST CONCENTRATIONS
- Range finding study: yes. A 3-day preliminary study was conducted

Reference substance (positive control):

not specified

Key result

Duration:

21 d

Dose descriptor:

NOEC

Remarks:

(nominal)

Effect conc.:

6.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: parent animal mortality and appearance of offspring

Key result

Duration:

21 d

Dose descriptor:

NOEC

Remarks:

(minimum value)

Effect conc.:

3.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: parent animal mortality and appearance of offspring

Remarks on result:

other: the chemical analysis showed a loss of test material of more than 20%, hence the NOEC is also reported as the minimum value - the lowest analysed concentration obtained during the test

Reported statistics and error estimates:

The parameters for fixing the NOEC of the substance were the mortality of the parent animals, the reproduction rate and the appearance of the first offspring during the test period. The Student's t-test and the U-test were the statistical methods used to calculate the first two parameters (Sachs, 1969), The U-test did not require the normal distribution of the test results and was therefore more suitable for evaluating the 21 d Daphnia reproduction test. The highest concentration level, which did not differ (NOEC) from the control, and the lowest, which did differ from the control in respect of mortality of the parent animals and of the reproduction rate, could be ascertained from the calculations. Moreover, in order to determine the NOEC, observations and evaluationswere also made of the appearance of the first offspring in the test preparations in comparison with the control preparations. Primarily, the results were expressed with reference to the nominal concentration. If, however, the chemical analysis showed a loss of the tested substance of more than 20%, then the lowest analysed concentration (minimum value) obtained during the test was also given for the NOEC. The aim was to counteract the customary discrepancies between interpretation and the reproducibility of chemical measured data which move within a range of variance.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study the 21-day NOEC to the aquatic invertebrate, Daphnia magna, was determined to be 6.3 mg/L (nominal). Based on the lowest measured concentration the 21-day NOEC was determined to be 3.2 mg/L.

Executive summary:

Investigations were carried out in order to determine the "no observed effect concentration" (NOEC) of 73 environmentally relevant substances in the 21 d Daphnia reproduction test. The test was conducted in line with the "Provisional Procedure: extended toxicology test with Daphnia magna (determination of NOEC for reproduction rate, mortality and the time of the first appearance of offspring; 21 d)" as of 1 January 1984, issued as the "Recommendation of the Federal Environmental Agency on the Performance of Testing according to Section 5, para 1 No. 3 of the Regulation on Application Documents and Evidence under the Chemicals Act" (Federal Environmental Agency).

Under the conditions of the study the 21-day NOEC to the aquatic invertebrate, Daphnia magna, was determined to be 6.3 mg/L (nominal). Based on the lowest measured concentration the 21-day NOEC was determined to be 3.2 mg/L. The validity criteria were fulfilled.

Description of key information

Under the conditions of the study the 21-day NOEC to the aquatic invertebrate, Daphnia magna, was determined to be 6.3 mg/L (nominal). Based on the lowest measured concentration the 21-day NOEC was determined to be 3.2 mg/L. The validity criteria were fulfilled.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

3.2 mg/L

Additional information

Investigations were carried out in order to determine the "no observed effect concentration" (NOEC) of 73 environmentally relevant substances in the 21 d Daphnia reproduction test. The test was conducted in line with the "Provisional Procedure: extended toxicology test with Daphnia magna (determination of NOEC for reproduction rate, mortality and the time of the first appearance of offspring; 21 d)" as of 1 January 1984, issued as the "Recommendation of the Federal Environmental Agency on the Performance of Testing according to Section 5, para 1 No. 3 of the Regulation on Application Documents and Evidence under the Chemicals Act" (Federal Environmental Agency). The study was awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).

Under the conditions of the study the 21-day NOEC to the aquatic invertebrate, Daphnia magna, was determined to be 6.3 mg/L (nominal). Based on the lowest measured concentration the 21-day NOEC was determined to be 3.2 mg/L. The validity criteria were fulfilled.