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

EU Method C.2 (Acute Toxicity for Daphnia)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

HPLC-UV/vis

Details on sampling:

Control: at 48 hours (on 2017-10-27)
Test concentration/s: 25, 50 and 100 mg/L in the freshly prepared media (on 2017-10-25 and 2017-10-26 ) and in the media after 24 h of exposure (on 2017-10-26 and 2017-10-27) according to the semi-static conditions

Vehicle:

no

Remarks:

Auxiliaries: ultrasonic bath, a magnetic stirrer and folded filters

Details on test solutions:

Pre-treatment of test item and preparation of test item concentrations
- 100.3 mg of the test item were added to 1 litre of dilution water on 2017-10-24 and 100.7 mg of the test item were added to 1 litre of dilution water on 2017-10-25, 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 7.8 on 2017-10-25 and 7.9 on 2017-10-26
- to produce the different test item concentrations appropriate amounts of the stock solution were diluted with dilution water to a volume of 500 mL
- 50 mL of the prepared solutions were taken per replicate and 0.5 mL of dilution water was given to all replicates resulting in the final nominal concentration

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:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

14.8 °dH (= 264 mg/L CaCO3)

Test temperature:

20.0 - 20.6 °C

pH:

7.8 - 8.0

Dissolved oxygen:

8.8 - 9.1 mg/L

Nominal and measured concentrations:

nominal [mg/L]: 25, 50, 100
measured (0 h, geometric mean) [mg/L]: 0.294, 0.578, 1.155
measured (24 h, geometric mean) [mg/L]: 0.268, 0.48, 0.837
measured (48 h, geometric mean) [mg/L]: 0.252, 0.393, 0.533

Effective concentrations ranged from 1.1 % to 1.2 % of nominal values in the freshly prepared media and from 0.5 % to 1.0 % of nominal values in the media after 24 hours of exposure.

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: 3 test concentrations plus 1 control, 5 neonates per vessel, 4 replicates per concentration/control
- no feeding during the exposure period
- semi-static system
- Method of initiation: neonates were placed in prepared media
- Photoperiod: 16 h light : 8 h dark
- Temperature of incubation unit: 19.6 to 19.8°C
- Aeration: none
- Test item concentration/s: 25, 50 and 100 mg/L (nominal)
- Method of administration: stock solution
- Medium renewal: daily
- 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.:

> 0.797 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

The results are expressed in terms of geometric mean measured concentrations.
Effective concentrations ranged from 1.1 % to 1.2 % of nominal values in the freshly prepared media and from 0.5 % to 1.0 % of nominal values in the media after 24 hours of exposure.

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 hours of exposure no toxic effects against Daphnia were observed at a test concentration of 0.797 mg/L for CN-Ethyl-TH-naphthyridin.

Executive summary:

A 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) to assess the acute toxicity of CN-ethyl-TH-naphthyridin to Daphnia magna STRAUS under semi-static conditions. The Daphnia were exposed to a range of concentrations, nominally 25, 50 and 100 mg/L of CN-ethyl-TH-naphthyridin dissolved in dilution water. Auxiliaries used to prepare the test media were an ultrasonic bath, a magnetic stirrer and folded filters. Observations were made on the swimming ability and the immobilisation rate, respectively, after 24 and 48 hours of exposure. After 48 hours of exposure an EC50 of higher than 0.797 mg/L was determined. The results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 1.1 % to 1.2 % of nominal values in the freshly prepared media and from 0.5 % to 1.0 % of nominal values in the media after 24 hours of exposure. No toxic effects against Daphnia were observed at a test concentration of 0.797 mg/L after 48 h under exposure conditions.

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 semi-static conditions. The Daphnia were exposed to a range of concentrations, nominally 25, 50 and 100 mg/L of CN-ethyl-TH-naphthyridin dissolved in dilution water.

No toxic effects against Daphnia were observed at a test concentration of 0.797 mg/L after 48 h under exposure conditions.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.797 mg/L

Additional information

"Should read: 48 h EC 50: >0.797 mg/L"

The results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 1.1 % to 1.2 % of nominal values in the freshly prepared media and from 0.5 % to 1.0 % of nominal values in the media after 24 hours of exposure.