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Long-term toxicity to aquatic invertebrates

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Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
See analogue justification attached to chapter 13.
Reason / purpose for cross-reference:
read-across source
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 183 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other:
Remarks:
Source: EC 701-177-3, LAUS, 2017, D. magna, 21 d
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 Nov - 06 Dec 2017
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Version / remarks:
02 Oct 2012
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: OECD guidance no. 23 on Aquatic Toxicity Testing of Difficult Substances and Mixtures
Version / remarks:
14 Dec 2000
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Mainz, Germany (08 Apr 2015)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Samples for analytical determinations were taken from the new solutions at the beginning of the tests, and from the old solutions (with and without daphnia and algae) at the end of the test (set 1).
Additional samples from the new and the old solutions were taken on day 5, day 7, day 9 and day 12. In the control, the content of the test item was measured at the beginning and at the end of each study.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: For the test, a saturated solution of 100 mg/L was prepared by mixing respective amounts of test item in dilution water and shaking vigorously for 24 h. The resulting solution was then filtered through a 0.45 µm cellulose ester filter after which the solutions were clear and colorless. The lower concentrations for both Experiments were prepared by dilution of the membrane filtered, saturated solution with dilution water.
- Differential loading: No
- Controls: Dilution water without test item
- Evidence of undissolved material: No, the solutions were clear and colorless after filtration.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Planktonic crustacean / water flea
- Strain/clone: Berlin
- Source: Umweltbundesamt Berlin, Germany (27 Sep 2007)
- Animal husbandry: In-house according to ES IS 6341, following SOP 115 002 01, edition 12 (adopted 12 Feb 2015). Vessels: 2L glass beakers; Medium: M4 medium (Elendt); Food: Green alga Desmodesmus subspicatus, twice a week; Photo period: 16 h light / 8 h dark (neon tubes); Temperature: 20 ± 2 °C
- Feeding during test: The animals were fed on each working day. On weekends, the Daphnia were not fed. On Fridays, the double amount of alga suspension was added into the test vessels.
- Sex and age at test start: Females between 0 - 24 h old

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
23 h before the start of set 1 and 21 h before the start of set 2, the adult animals were separated from the young. 22 h (set 1) and 20 h (set 2) later, the adults were caught with the help of a glass tube, and the newborn daphnia, aged 0 - 23 h (set 1) and 0 - 22 h (set 2), were sieved from the medium and immediately placed into a 250 mL beaker containing diliution water. After a settling period of 30 min, animals which showed no apparent damage were used for the tests.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
267 - 356 mg CaCO3/L
Test temperature:
19.5 - 21.5 °C
pH:
7.5 - 8.7
Dissolved oxygen:
8.5 - 9.7 mg/L
Nominal and measured concentrations:
Control, 4.6, 10, 22, 46 and 100 mg/L (nominal)
Control, 27, 47, 102, 183 and N.A. µg/L (time-weighted mean)
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL glass beakers
- Renewal rate of test solution: 3 times/week
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10
- Biomass loading rate: 80 mL/animal, animals were kept individually
- Other: 1 additional replicate for analytical measurement

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Deionised water enriched with minerals, according to the M4 composition by Elendt, as described in the OECD guideline.
- CaCl2*2H2O: 293.80 mg/L
- MgSO4*7H2O: 123.30 mg/L
- NaHCO3: 64.80 mg/L
- KCl: 5.80 mg/L
- NaNO3: 274 µg/L
- K2HPO4: 143 µg/L
- Na2SiO3*9H2O: 10 mg/L
- H3BO3: 2.86 mg/L
- Na2EDTA*2H2O: 2.5 mg/L
- FeSO4*7H2O: 0.9955 mg/L
- MnCl2*4H2O: 0.3605 mg/L
- LiCl: 0.306 mg/L
- SrCl2*6H2O: 0.152 mg/L
- RbCl: 0.071 mg/L
- Na2MoO4*2H2O: 0.0615 mg/L
- CuCl2*2H2O: 16.75 µg/L
- NaBr: 16 µg/L
- ZnCl2: 13 µg/L
- CoCl2*6H2O: 10 µg/L
- KI: 3.25 µg/L
- Na2SeO3 *5 H2O: 3.33 µg/L
- NH4VO3: 0.575 µg/L
- ThiaminHCl: 75 µg/L
- Cyanocobalamin: 1 µg/L
- D+Biotin: 0.75 µg/L
- Culture medium different from test medium: Culture medium same as dilution water (M4-medium).
- Intervals of water quality measurement: Day 2, 5, 12 and 19

OTHER TEST CONDITIONS
- Photoperiod: 16 h light / 8 h dark
- Light intensity: 1000 lux (neon tubes)

EFFECT PARAMETERS MEASURED:
- Mortality and Reproduction of surviving daphnia: 3 times/week

TEST CONCENTRATIONS
- Spacing factor for test concentrations: ca. 2.17
- Range finding study: Not specified
Reference substance (positive control):
not specified
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 183 µg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
- Behavioural abnormalities: No abnormal behaviour or appearance of the surviving daphnia was observed.
- Mortality of control: 0%
- Any observations that might cause a difference between measured and nominal values: No
- Effect concentrations exceeding solubility of substance in test medium: No
Reported statistics and error estimates:
Statistical analyses were performed with ToxRat Professional v3.2.1.
Statistical design: Hypothesis testing (NOEC) and regression (ECx).

VALIDITY CRITERIA

The study fulfilled the validity criteria defined by the guideline (Table 1). Furthermore, the oxygen concentration was 8.5 mg/L (required: , 3.0 mg/L) the pH range 7.5 - 8.4 (required 6 - 9) and the pH variation was 0.6 (required: 1.5). Thus, the test is considered valid and reliable.

Table 1: Validity criteria for OECD 211.

Criterion from the guideline

Outcome

Validity criterion fulfilled

The mortality of the parent animals in the control (femaleDaphnia) does not exceed 20% at the end of the test.

Mortality of parent animals in the control was 0%.

Yes

The mean number of living offspring produced per parent animalsurvivingat the end of the test is ≥ 60 in the control.

The mean surviving offspring in the control was 93.

Yes

 

ANALYTICAL RESULTS

There was a weak correlation between the nominal concentrations and the measured concentrations and a weak stability of the test item during the exposure period (Table 2 - 5). In aged test solutions, hardly any test item was detectable. Therefore, results were based on the time-weighted mean of the measured concentrations in the new and old solutions. For the calculation of the time-weighted mean, the limit of detection (10 µg/L) was used for calculation where no test item was detectable.

Table 2.Measured Concentrations Days 0 – 5 set 1

Nominal Conc. in mg/L

Measured Conc. day 0 in µg/L

Measured Conc. day 5 old solution with algae in µg/L

Measured Conc. day 5 old solution without algae in µg/L

Measured Conc. day 5 new solution algae in µg/L

4.6

126

10**

n. d.

62

10

252

10**

n. d.

151

22

514

31

n. d.

344

46

1061

41

87

657

100

2177

*

*

*

n. d. = not detectable

* not measured because all daphnia were found dead on day 2

**10 µ/L = LOD (lowest calibration level)

Table 3.Measured Concentrations Days 7 – 9 set 1

Nominal Conc. in mg/L

Measured Conc. day 7 old solution with algae in µg/L

Measured Conc. day 7 old solution without algae in µg/L

Measured Conc. day 7 new solution algae in µg/L

Measured Conc. day 9 old solution with algae in µg/L

Measured Conc. day 9 old solution without algae in µg/L

4.6

10**

n. d.

40

10**

n. d.

10

10**

n. d.

100

10**

n. d.

22

12

n. d.

255

45

n. d.

46

37

38

417

92

11

n. d. = not detectable

**10 µ/L = LOD (lowest calibration level)

 

Table 4.Measured Concentrations Days 9 – 21 set 1

Nominal Conc. in mg/L

Measured Conc. day 9 new solution algae in µg/L

Measured Conc. day 12 old solution with algae in µg/L

Measured Conc. day 12 old solution without algae in µg/L

Measured Conc. day 12 new solution algae in µg/L

Measured Conc. day 21 old solution with algae in µg/L

4.6

53

10**

n. d.

30

10**

10

108

10**

n. d.

78

10**

22

271

10**

n. d.

172

17

46

481

15

n. d.

327

22

n. d. = not detectable

**10 µg/L = LOD (lowest calibration level)

Table 5. Time-Weighted Mean set 1

Nominal Conc. in mg/L

Time-Weighted Mean in µg/L

4.6 mg/L

27

10 mg/L

47

22 mg/L

102

46 mg/L

183

 

BIOLOGICAL RESULTS

No toxicity (mortality and inhibition) was observed at the nominal concentration of 22 mg/L (experimental set 1). Therefore, the lower concentrations of 1.0 and 2.2 mg/L, which were additionally tested in the experimental set 2, were not necessary for evaluation and the entire set 2 was aborted on Day 14.

At the nominal concentration of 46 mg/L only 1 animal survived but the number of offspring of the surviving animal was not significant compared to the control. Thus, no statistically significant inhibition of reproduction was observed in any treatment (Table 6). The effect values based on the time-weighted mean of the measured concentrations are summarized in Table 7 and Table 8.

Table 6. Fecundity (set 1)

Treatment

Total Offspring

Surviving Parent Animals

Mean Offspring per Surviving Parent Animal

Inhibition of Reproductionin %

Blank Control

934

10

93

0

4.6 mg/L

1030

10

103

-10

10 mg/L

952

10

95

-2

22 mg/L

1098

10

110

-18

46 mg/L

77

1

77

18

100 mg/L

0

0

--

--

 

Table 7.Biological Results cumulative offspring per survived parent

Parameter

Value

NOEC

≥183 µg/L

LOEC

> 183 µg/L

EC50

> 183 µg/L

 

Table 8.Biological Results Immobility

Parameter

Value

NOEC

102 µg/L

LOEC

183 µg/L

EC50

141.46 µg/L

 

Validity criteria fulfilled:
yes
Remarks:
For further details please refer to “Any other information on results incl. tables”.

Description of key information

NOEC (21d) ≥ 183 µg/L for Daphnia magna (meas. TWA, OECD 211); read-across

Key value for chemical safety assessment

Additional information

No studies investigating the long-term toxicity to aquatic invertebrates are available for Reaction mass of N-(1-oxooctadecyl)sarcosine and N-hexadecanoyl-N-methylglycine (EC 947-850-7). Therefore, in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 a read-across to the structurally related source substances N-methyl-N-(C18-(unsaturated)alkanoyl)glycine (EC 701-177-3) was conducted.

The chemical properties of the target and source substance are similar due to the structural similarities, i.e., sarcosine head group and the hydrocarbon tail. In addition, due to the pKa of the target substance (pKa = 3.96, major constituent), at physiological pH values (above 6) the target substance is expected to be in the anionic form, as is the source substance. As a result, the chemistry of the target and source substance, in solution (above pH 6), are expected to be similar. Thus, the source substance is considered suitable representative for the evaluation of the toxicity to aquatic invertebrates of the target substance. The read-across approach is justified in detail within the analogue justification in IUCLID section 13.

The study conducted with the source substance N-methyl-N-(C18-(unsaturated)alkanoyl)glycine (EC 701-177-3) was performed according to OECD 211 (GLP) with Daphnia magna under semi-static conditions. The test organisms were exposed to nominal concentrations of 4.6, 10, 22, 46 and 100 mg/L. After only 2 days strong mortality was observed in the two highest concentrations. Therefore, parallel to the ongoing experiment (set 1), on day 7, additional control and test replicates using lower test concentrations of 1.0 mg/L and 2.2 mg/L were started (set 2). As no toxicity, neither mortality nor inhibition of reproduction was observed in the first experiment at the nominal concentration 22 mg/L, the additional tested lower concentrations 1.0 mg/L and 2.2 mg/L were not necessary for evaluation and set 2 was aborted on day 14. Analytical measurements verified the test item concentration to be 27, 47, 102 and 183 µg/L(TWA) for the nominal test concentrations 4.6, 10, 22 and 46 mg/L. The NOEC (21d) was determined to be ≥ 183 µg/L (meas. TWA).

Based on the available results from a structurally related read-across substance (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5), which is characterized by a comparable structure and physico-chemical properties, it can be concluded that the target substance Reaction mass of N-(1-oxooctadecyl)sarcosine and N-hexadecanoyl-N-methylglycine (EC 947-850-7) will exhibit comparable effects on aquatic invertebrates.