2,4,6-trimethylpyridine

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:

May 12, 2020 to June 11, 2020

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:

April 13, 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations:
all concentrations and control
- Sampling method:
The samples were taken from the biological phase of the study. Duplicate samples from the freshly prepared test media of all test concentrations and the control were taken at the start of the test. 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 control were collected at the end of the test (after 48 hours) by pouring together the contents of the test beakers of each treatment. All samples were diluted by a factor of 2 with acetonitrile. Additional samples of the control and the dilution solvent were taken at each sampling 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. Afterwards the samples were again stored deep frozen (≤ -20 °C) and will be kept stored up to the date of the final report.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
Test water: Reconstituted Water (Elendt "M4")
Pre-experiments were performed to determine a suitable concentration range and to establish suitable methods to prepare the test solutions.
Test Concentrations:
100, 50, 25, 12.5 and 6.3 mg test item/L (spacing factor 2) and a control
Control: In the control, test water was used without addition of the test item.
The test medium of the highest test concentration of nominal 100 mg test item/L was prepared by dissolving 100.3 mg test item into 1003 mL test water by intense stirring for 10 minutes. Adequate volumes of this test medium were diluted with test water to prepare the test media of the other desired test concentrations.
The test media were prepared just before introduction of the daphnids (= start of the test).

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna (Straus)
- Strain/clone: clone 5
- Age at study initiation: From 1.75 to 5.75 hours old
- Source: The daphnids were bred in the laboratories of ibacon under similar temperature and light conditions as used in the test. The cultivation of the parental daphnids was performed in Elendt M4 medium. The test organisms were not first brood progeny. The daphnids in the stock culture were fed at least on all working days with green algae (Desmodesmus subspicatus) freshly grown in the laboratories of ibacon.

ACCLIMATION
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

Post exposure observation period:

none

Test temperature:

19.5 to 20.2 °C at test start; 20.0 to 20.3 °C at test end

pH:

8.0 to 8.4 at test start; 8.0 to 8.3 at test end; and thus the pH-value did not vary by more than 1.5 units

Dissolved oxygen:

8.5 to 8.9 mg/L at test start; 8.5 to 8.6 mg/L at test end

Nominal and measured concentrations:

nominal: 0, 100, 50, 25, 12.5 and 6.3 mg test item/L
At the start of the test 103 % of the nominal test concentrations were found (average of all test concentrations). After 48 hours test duration, 95 % of the nominal value was determined (average of all test concentrations). During the test the daphnids were exposed to a mean of 99 % of nominal.

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beaker
- Type: closed
- Volume of solution: appr. 110 mL
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates):4
- No. of vessels per control (replicates):4

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light : 8 h dark
- Light intensity: 380 to 760 lux

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

96.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

80.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the test item concentration of 50 mg test item/L. At the concentration of 100 mg test item/L 12 animals were immobile. At the concentrations of 25, 50 and 100 mg test item/L some Daphnia were moving slower compared to the control, had agglutinated antennae or were stuck to the water surface.

Table 1. Summary of Biological Results Nominal Concentration % of immobilised daphnids after   [mg test item/L] 24 hours 48 hours   Control 0 0   6.3 0 0   12.5 0 0   25 0 0   50 0 0   100 80 60   EC50 [mg test item/L]: 90.5 96.5   95 % CI [mg test item/L]: n.d. n.d.   EC20 [mg test item/L]: 81.8 85.6   95 % CI [mg test item/L]: n.d. n.d.   EC10 [mg test item/L]: 77.7 80.4   95 % CI [mg test item/L]: n.d. n.d.   NOEC [mg test item/L]: 50.0 50.0   LOEC [mg test item/L]: 100.0 100.0   Values refer to nominal test concentrations CI: Confidence interval n.d.: not determinable   Table 2: Summary of Analytical Results Sample Description [mg test item/L] % of nominal* RSD [%]  n    Control  n.a.  n.a.  4    6.3  101  4  4    12.5  104  4  4    25  85  24  4    50  104  2  4    100  100  2  4   *mean value of all measured samples per treatment group RSD: relative standard deviation per treatment group n: number of analysed samples n.a.: not applicable

Validity criteria fulfilled:

yes

Conclusions:

The 48-hour NOEC was determined to be 50.0 mg test item/L. The 48-hour LOEC was determined to be 100.0 mg test item/L and the 48-hour EC50 value was determined to be 96.5 mg test item/L (nominal values).

Executive summary:

The toxic effect of the test item 2,4,6-Collidine to Daphnia magna was assessed according to OECD Guideline No. 202. For this purpose, young daphnids (< 24 hours old) were exposed in a static test to various concentrations under defined conditions for 48 hours. The recorded effects were the mobility of the daphnids after 24 and 48 hours. This study encompassed 6 treatment groups (5 dose rates of the test item and a control) each containing 20 individuals. The mobility of the daphnids was determined by visual observation after 24 and 48 hours. The test concentrations were 0 (control), 100, 50, 25, 12.5 and 6.3 mg test item/L (spacing factor 2). After 48 hours of exposure no immobilisation of the test animals was observed in the control (validity criteria fulfilled) and up to and including the test item concentration of 50 mg test item/L. At the concentration of 100 mg test item/L 12 animals were immobile. At the concentrations of 25, 50 and 100 mg test item/L some Daphnia were moving slower compared to the control, had agglutinated antennae or were stuck to the water surface. As a conclusion, the 48-hour NOEC was determined to be 50.0 mg test item/L. The 48-hour LOEC was determined to be 100.0 mg test item/L and the 48-hour EC50 value was determined to be 96.5 mg test item/L (nominal values). The initial concentrations and the maintenance of the exposure concentrations during the test were verified in the analytical part. All reported results refer to nominal values since the concentrations of the test item were within ± 20% of the nominal concentrations during the test.

Description of key information

The 48-hour NOEC was determined to be 50.0 mg test item/L. The 48-hour LOEC was determined to be 100.0 mg test item/L and the 48-hour EC50 value was determined to be 96.5 mg test item/L (nominal values).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

96.5 mg/L

Additional information

The toxic effect of the test item 2,4,6-Collidine to Daphnia magna was assessed according to OECD Guideline No. 202. For this purpose, young daphnids (< 24 hours old) were exposed in a static test to various concentrations under defined conditions for 48 hours. The recorded effects were the mobility of the daphnids after 24 and 48 hours. This study encompassed 6 treatment groups (5 dose rates of the test item and a control) each containing 20 individuals. The mobility of the daphnids was determined by visual observation after 24 and 48 hours. The test concentrations were 0 (control), 100, 50, 25, 12.5 and 6.3 mg test item/L (spacing factor 2). After 48 hours of exposure no immobilisation of the test animals was observed in the control (validity criteria fulfilled) and up to and including the test item concentration of 50 mg test item/L. At the concentration of 100 mg test item/L 12 animals were immobile. At the concentrations of 25, 50 and 100 mg test item/L some Daphnia were moving slower compared to the control, had agglutinated antennae or were stuck to the water surface. As a conclusion, the 48-hour NOEC was determined to be 50.0 mg test item/L. The 48-hour LOEC was determined to be 100.0 mg test item/L and the 48-hour EC50 value was determined to be 96.5 mg test item/L (nominal values). The initial concentrations and the maintenance of the exposure concentrations during the test were verified in the analytical part. All reported results refer to nominal values since the concentrations of the test item were within ± 20% of the nominal concentrations during the test.