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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
The stability of the test item under test conditions was tested during this study. The test item dissociates in the aqueous phase to give a mixture of ethylene glycol and formaldehyde. This process was demonstrated to be almost complete up to concentrations of at least 28 mg/L (data given by the sponsor).
Analytical monitoring:
yes
Details on sampling:
Chemical analyses performed with the test solutions at the start of incubation and after 24h (four times during the test duration).
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test solutions were prepared freshly every day of the test.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna STRAUS (clone 5)
- Source: Laboratory breed originally derived from Umweltbundesamt Berlin, Germany
- Age of parental stock: < 24 h
- Breeding method: Animals were transferred in new test medium at an interval of 1 to 3 days followed by feeding
- Feeding during test: Yes, Desmodesmus subspicatus
- Food type: Desmodesmus subspicatus- and/or Chlorella spp.-cells
- Amount: 0.1-0.2 mg C/Daphnia
- Frequency: Every 1 to 3 days

ACCLIMATION
- Acclimation period: Acclimation for 3 weeks prior to test
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Test temperature:
19.0 – 20.7°C, measured daily
pH:
7.30 - 9.37, measured daily
Dissolved oxygen:
8.0 - 9.1 mg/L, measured daily
Nominal and measured concentrations:
Initial concentrations: 20.0, 8.0, 3.2, 1.28, 0.512, 0.2048 mg/L + control
Actual concentrations: In freshly prepared test solutions, the recovery of formaldehyde was in the range between 87.1 and 114.3% of the nominal concentrations. The test item remained stable at >80% of the initial values. For this reason, the results of this test are based on the nominal concentrations tested.
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL
- Renewal rate of test solution: 1 / day
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 13
- Biomass loading rate: 100 mL/animal

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M7 medium, according to Guideline
- Ca/Mg ratio: according to Guideline

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: Day/night : 16h/8h
- Light intensity: Mean intensity 1.00 klx ≈ 15.0 µE/m2s

EFFECT PARAMETERS MEASURED:
Offspring animals were counted daily and were then eliminated from the treatments.
Mortality
Number of living offspring produced per parent animal
Intrinsic rate of population growth
Age at first reproduction
Size of the parent animals, measured at test end
Daily examination of biological parameters, except size of animals (at end of test)
Reference substance (positive control):
yes
Remarks:
A reference item was not tested within this study. In order to verify the sensitivity of the test system towards toxic items the effect of potassium dichromate towards different animals of this breed was tested once a month.
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
20 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 h
Dose descriptor:
EC10
Effect conc.:
10.8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: 95% CI 10.7-11.0 mg/L
Duration:
21 d
Dose descriptor:
other: EC20
Effect conc.:
15.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: 95% CI 15.2-15.4 mg/L
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
29.4 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: 95% CI 29.0-29.8 mg/L
Details on results:
No test item related effects were found for the additional endpoints (i) intrinsic rate of population growth, (ii) age at first reproduction and (iii) size of the parent animals at test end. Thus, NOECs for all additional endpoints are ≥ 20 mg/L.
Results with reference substance (positive control):
EC50 (24h) in the test period was 1.5 mg/L potassium dichromate
Reported statistics and error estimates:
The statistical calculations were done using the commercial computer program ToxRatPro Version2.09 (08.11.2006)

Results of measurements:

Nominal Conc. [mg/L]

Recovery [%] after 24 h

6 d

10 d

13 d

17 d

0.205

87.1

88.0

114.3

90.7

0.512

89.2

89.2

89.2

88.4

1.280

74.9

87.9

87.9

88.8

3.200

106.6

89.1

106.6

80.9

8.000

99.0

94.2

98.3

91.4

20.000

98.8

93.0

99.4

105.5

Effect data:  

Nominal Conc. [mg/L]

No. offspring / living parent

Dead parent animals

control

61.4

0

0.2048

61.3

1 (day 15)

0.512

61.5

2 (days <7, 16)

1.28

57.6

2 (days 5, 6)

3.20

58.0

1 (day <7)

8.00

58.5

0

20.0

42.3

0

 

Validity criteria fulfilled:
yes
Conclusions:
EGForm was found to be harmful towards daphnids reproduction
Executive summary:

The test was performed according to the OECD Guideline 211. The invertebrate Daphnia magna was used as the test organism. The animals were exposed to 6 concentrations of EGForm, ranging from 0.205 to 20.0 mg/L, and one control. The test was carried out in a semistatic system with daily renewal of the test solutions. All concentrations were tested using 13 replicates. The test was performed at 19.0 – 20.7 °C in Elendt 7 medium prepared as described in the Guideline. Within the test period of 21 days cumulative living offspring produced per parent animal was recorded for each concentration. Temperature, pH and oxygen content were measured daily in both freshly prepared and 24 h old test solutions. In addition, the age at first reproduction and (at the end of the test) the sizes of the parent animals were recorded. The stability of the test item was controlled by formaldehyde measurements in freshly prepared medium and after 24 h of incubation.

EGForm was found to be harmful towards daphnids reproduction. The numerical results are given below; all results refer to the nominal concentrations since formaldehyde was shown to be stable within the incubation period. All validity criteria according to the Guideline are met within the study.

A clear concentration-response relationship can be established from the study results. While at 8 mg/L no significant effects were observed, reproduction was inhibited by >10% at 20 mg/L.

No test item related effects were found for the additional endpoints intrinsic rate of population growth, age at first reproduction and size of the parent animals at test end. Thus, NOECs for all additional endpoints are ≥ 20 mg/L.

The test substance EGForm hydrolyses rapidly and completely in the test medium, forming ethylene glycol and formaldehyde. Formaldehyde is expected to dominate the toxicity of EGForm in aqueous solutions. Formaldehyde is expected to be not volatile in the test solution, and no losses due to adsorption are expected.

Analysis of the formaldehyde content in the test solutions proved the test item to remain stable at >80% of the initial values over the respective 24 h inbubation period. For this reason, the results of this test are based on the nominal concentrations tested.

Description of key information

A test on reproduction of Daphnia magna was performed according to the OECD Guideline 211 in a semistatic system. Test parameters were mortality, reproduction, the age at first reproduction and the size of the parent animals at the end of the test. The NOEC based on reproduction was found to be 8.0 mg/L. Analytical measurements revealed that the formaldehyde content remained stable at >80% of the initial values over the exposure period. Therefore, for deriving the effect values the nominal values can be used.

Key value for chemical safety assessment

EC10, LC10 or NOEC for marine water invertebrates:
8 mg/L

Additional information