1,6-Naphthyridine-3-carboxamide, 4-(4-cyano-2-methoxyphenyl)-5-ethoxy-1,4-dihydro-2,8-dimethyl-

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:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

HPLC and UV/VIS-detection

Details on sampling:

Stability of test concentrations during exposure was examined by chemical analysis (HPLC) at 0 and 48 hours:
Control at 48 h, test concentration (100 mg/L) at 0 and 48 h

Vehicle:

no

Details on test solutions:

Pre-treatment of test item and preparation of test item concentrations
- to produce the only test item concentration, 100.5 mg of the test item were added to 1 litre of dilution water, treated for 1 h in an ultrasonic bath and stirred for 24 h on a magnetic stirrer
- undissolved particles of the test item were removed by filtration using a folded filter (pore size 7 - 12 μm)
- pH was measured to be 7.9
- 50 mL of the solution were taken and diluted with 0.5 mL of dilution water resulting in a final concentration of 100 mg/L
- for each test item concentration and the control 4 replicates were prepared

Test organisms (species):

Daphnia magna

Details on test organisms:

- Name: Daphnia magna STRAUS, parthenogenetic females
- Source: Strain of Bundesgesundheitsamt Berlin
- Maintenance and Acclimatisation: A population of parthenogenetic females of synchronized age structure has been maintained for more than 20 years in the test facility under constant temperature conditions (20 +/- 2 °C) at a 16 : 8 hour light-dark photoperiod (light intensity: < 20 μE x m-2 x s-1). The culture water (so-called 'M4 medium') was partly renewed once a week. The Daphnia were exclusively fed unicellular green algae (Desmodesmus subspicatus) 'ad libitum'. Mortalities of parent Daphnia during the culture period were recorded daily. The neonates were separated from their parent Daphnia by filtration prior to the acute test

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

14.9 °dH

Test temperature:

20.0 - 20.6 °C

pH:

7.7 - 8.1

Dissolved oxygen:

8.5 - 8.7 mg/L

Nominal and measured concentrations:

nominal: 100 mg/L
measured: 21.36 mg/L (0 h), 21.122 mg/L (48 h)

Details on test conditions:

Exposure conditions
- Test vessels: 100 mL glass beakers covered with watch glasses holding 5 neonates in 50 mL of test medium
- Experimental design: 1 test concentration plus 1 control, 5 neonates per vessel, 4 replicates per concentration/control, no feeding during the exposure period, static system
- Method of initiation: neonates were placed in prepared media
- Photoperiod : 16 h light : 8 h dark
- Temperature of incubation unit: 19.4 to 19.6 °C
- Aeration: none
- Test item concentration/s: 100 mg/L
- Method of administration: direct weighing
- Medium renewal: none
- Duration of exposure: 48 hours
- Criteria of effects: item-induced alteration of the normal mobility behaviour and the loss of locomotory actions of the neonates, observed at 24 and 48 hours

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 21.36 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Validity criteria fulfilled:

yes

Remarks:

immobilisation and other abnormalities in the controls did not exceed 10 % by the end of the test; dissolved oxygen concentration remained above 3 mg/L throughout the exposure period.

Conclusions:

After 48 h of exposure to Rac-Amido-TH-naphthyridin no toxic effect against Daphnia was observed at a limit test concentration of 21.36 mg/L (nominal:100 mg/L).

Executive summary:

A study was performed to assess the acute toxicity of Rac-Amido-TH-naphthyridin to Daphnia magna STRAUS under static conditions. The study was conducted in accordance with the Council Regulation (EC) No 440/2008, Method C.2 ‘Acute toxicity for Daphnia’ (2008) which is equivalent to OECD Guideline for Testing of Chemicals No. 202 'Daphnia sp., Acute Immobilisation Test' (adopted April 13, 2004).

The Daphnia were exposed to a limit test concentration of nominally 100 mg/L of Rac-Amido-TH-naphthyridin dissolved in dilution water for 48 h. Auxiliaries used to prepare the test media were an ultrasonic bath, a magnetic stirrer and a folded filter.

During the test a temperature range of 18 - 22 °C was maintained in the test vessels, with a maximum temperature fluctuation of +/- 1 °C in each individual test. The temperature, the pH and the oxygen values were measured at the beginning and end of the test. Observations were made on the swimming ability and the immobilisation rate. At this concentration no toxic effects against Daphnia were observed at the end of the 48 hour study period, thus no statistical analysis was required to determine the EC 50. Immobilisation rates were recorded at 24-hour intervals. Additionally any abnormal behaviour or appearance of the Daphnia was reported every 24 hours. An 48h-EC50 > 21.36 mg/L was determined. The results are expressed in terms of initial concentrations.

Description of key information

After 48 h of exposure to Rac-Amido-TH-naphthyridin no toxic effect against Daphnia was observed at a limit test concentration of 21.36 mg/L (nominal: 100 mg/L).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

21.36 mg/L

Additional information

Should read: EC50 > 21.36 mg/L.