Nα-acetyl-DL-tryptophan

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:

15 - 17 Jun 2016

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:

13 Apr 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

30 May 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: SANCO/3029/99 rev.4 11/07/00: Residues: Guidance for generating and reporting methods of analysis in support of preregistration data requirements for Annex II (part A; Section 4) and Annex III (part A; Section 5) of directive 91/414.

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany (24 Sep 2013)

Analytical monitoring:

yes

Remarks:

HPLC-UV/VIS

Details on sampling:

- Concentrations: Control, 6.25, 12.5, 25, 50, and 100 mg test item/L
- Sampling method: Duplicate samples from the freshly prepared test media of all test concentrations and the controls were taken at the start of the test (0 h). For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, duplicate samples from the test media of all test concentrations and the controls were collected at the end of the test (48 h) by pouring together the contents of the test beakers of each treatment. All samples were diluted by a factor of 2 with acetonitrilie. Additional samples of the control and the dilution solvent were taken at test start and test end without any sample treatment.
- Sample storage conditions before analysis: All samples were stored in a freezer (≤ - 20 °C), protected from light until analysis was performed.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test medium of the highest test concentration of nominal 100 mg test item/L was prepared by dissolving 80.4 mg test item into 804 mL test water by short ultrasonic treatment for 5 min and intense stirring for 1 h. Adequate volumes of this test medium were diluted with test water to prepare the test media just before introduction of the Daphnia.
- Controls: Reconstituted water (test water) without test item
- Evidence of undissolved material: No remarkable observations

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain/clone: Clone 5
- Source: In-house laboratory culture
- Age at test start: 2.25 - 20.5 h old (female). The test organisms were not first brood progeny.
- Breeding conditions: Under similar temperature and light conditions as in the test. The cultivation of the parental Daphnia was performed in Elendt M4 medium (reconstituted water).
- Food type (breeding): green algae (Desmodesmus subspicatus)
- Frequency: On all working days

ACCLIMATION
- Acclimation period: Not necessary since the test was performed in the same medium as the culturing.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

2.5 mmol/L (= 250 mg/L) as CaCO3

Test temperature:

20.0 - 21 °C (0 h)
20 °C (48 h)

pH:

7.4 - 8.0 (0 h)
7.6 - 8.0 (48 h)

Dissolved oxygen:

8.5 - 8.9 mg O2/L (0 h)
8.3 - 8.5 mg O2/L (48 h)

Nominal and measured concentrations:

Control, 6.25, 12.5, 25, 50, and 100 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: Beaker
- Type: Covered with a lid.
- Material, size, headspace, fill volume: Material: glass; Size: 100 mL; Fill volume: 60 mL
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 1 daphnid/12 mL

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: According to guideline
- Alkalinity: 0.9 mmol/L
- Conductivity: < 5 µScm^-1
- Culture medium different from test medium: Test medium same as culture medium
- Intervals of water quality measurement: The water temperature, pH-values and dissolved oxygen concentrations were determined at test start and test end in each treatment group.

OTHER TEST CONDITIONS
- Photoperiod: 16 h light/ 8 h dark
- Light intensity: 550 - 810 lux

EFFECT PARAMETERS MEASURED:
- Mobility: after 24 and 48 h

RANGE-FINDING STUDY
- Test concentrations: Yes
- Results used to determine the conditions for the definitive study: Yes, non-GLP pre-experiments were performed to determine a suitable concentration range.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mortality of control: 0%
- Any observations that might cause a difference between measured and nominal values: No remarkable observations, clear test medium.
- Effect concentrations exceeding solubility of substance in test medium: No

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 (48 h) = 0.986 mg mg/L
- Other: Test dating January 2016.

Reported statistics and error estimates:

No statistical analysis was performed. The EC50 could not be quantified due to the absence of toxicity of the test item.

ANALYTICAL RESULTS

At the start of the test 108% of the nominal test concentrations were found (average of all test concentrations). After 48 h test duration, 97% of the nominal value was determined (average of all test concentrations). During the test the daphnids were exposed to a mean of 103% of nominal. Therefore, all reported results refer to nominal concentrations.

Description of key information

EC50 (48 h) > 100 mg/L (nominal, OECD 202, D. magna)

Additional information

There is one study available in which the short-term toxicity of N-Acetyl-DL-tryptophan (CAS 87-32-1) was assessed according to OECD guideline 202 and GLP.

In a static test, Daphnia magna was exposed to 6.25, 12.5, 25, 50, and 100 mg/L nominal test item concentrations for 48 h. Test item concentrations were analytically verified by HPLC-UV/VIS at the start (0 h) and end of the test (48 h). The number of immobile organisms was recorded after 24 and 48 h.

Analytical measurements found 108% of the nominal test concentrations at the start of the test and 97% of the nominal value at the end. Therefore, all reported results refer to nominal concentrations. After 48 h of exposure no immobilization of the test animals was observed in the control and up to and including the highest test item concentration of 100 mg/L (nominal). The EC50 (48 h) was therefore > 100 mg/L (nominal).