1,6-Naphthyridine-3-carboxylic acid, 4-(4-cyano-2-methoxyphenyl)-1,4,5,6-tetrahydro-2,8-dimethyl-5-oxo-, 2-cyanoethyl 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:

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-UV/VIS

Details on sampling:

Sampling schedule:
Control: at 48 hours
Test concentration: at 0 and 48 hours

Vehicle:

no

Remarks:

auxiliaries used were an ultrasonic bath and a magnetic stirrer

Details on test solutions:

Pre-treatment of test item and preparation of test item concentrations
- 100 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 of 7 - 12 μm)
- pH was measured to be 7.8

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:

15.2 °dH (= 271 mg/L CaCO3)

Test temperature:

21.0 - 21.3

pH:

7.7 - 7.9

Dissolved oxygen:

8.1 - 9.8 mg/L

Nominal and measured concentrations:

nominal [mg/L]: 100 mg/L
measured [mg/L]: 7.23 (at 0 h), 5.37 (at 48 h)

Details on test conditions:

Exposure conditions
- Test vessels: 100 mL glass beakers covered with watch glasses holding 5 neonates in 50 mL 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: 20.2 to 20.6 °C
- Aeration: none
- Test item concentration/s: 100 mg/L (nominal)
- 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.:

> 6.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No toxic effects against Daphnia were observed at a limit test concentration at the limit of water solubility under exposure conditions.
The results are expressed in terms of geometric mean measured concentrations (at 24 and 48 h). Effective concentration corresponded to 7.2% of nominal values at 0 hours and to 5.4 % of nominal values at 48 hours.

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:

No toxic effects against Daphnia were observed after 48 h at a limit test concentration at the limit of water solubility (48h-EC50 > 6.2 mg/L) for CN-ethyl-TH-naphthyridinon.

Executive summary:

The study was conducted to assess the acute toxicity of CN-ethyl-TH-naphthyridinone to Daphnia magna STRAUS under static conditionsin 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).

A range finding test preceded the main test. It provided information about the range of concentrations which were used in the main test. The following nominal concentrations of the test item were tested in the range finding test: 0.01, 0.1, 1.0, 10 and 100 mg/L.

The Daphnia were exposed to a limit test concentration of nominally 100 mg/L of CN-ethyl-TH-naphthyridinon dissolved in dilution water for a period of 48 hours. Auxiliaries used to prepare the test media were an ultrasonic bath, a magnetic stirrer and a folded filter. The test was conducted as a static test with the test medium unchanged throughout the duration of the test. 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, respectively, after 24 and 48 hours of exposure. An EC50 < 6.2 mg/L was determined after 48 h.

No toxic effects against Daphnia were observed at a limit test concentration at the limit of water solubility under exposure conditions. The results are expressed in terms of geometric mean measured concentrations. Effective concentration corresponded to 7.2 % of nominal values at 0 hours and to 5.4 % of nominal values at 48 hours.

Description of key information

A study was conducted in accordance with method EC 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) to assess the acute toxicity of CN-ethyl-TH-naphthyridin to Daphnia magna STRAUS under static conditions. The Daphnia were exposed to a limit test concentration of nominally 100 mg/L of CN-ethyl-TH-naphthyridinon dissolved in dilution water for a period of 48 hours.

No toxic effects against Daphnia were observed after 48 h at a limit test concentration at the limit of water solubility (48h-EC50 > 6.2 mg/L) for CN-ethyl-TH-naphthyridinon.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

6.2 mg/L

Additional information

Should read "EC50 > 6.2 mg/L"