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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.20 (Daphnia magna Reproduction Test)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Remarks:
DOC
Details on sampling:
Sampling schedule:
Control: on day 0, 12 and 19 in the freshly prepared media; on day 3, 14 and 21 in the old media
Test concentrations: 10 mg/L on day 0, 12 and 19 in the freshly prepared media; on day 3, 14 and 21 in the old media
Vehicle:
no
Remarks:
auxiliaries used: ultrasonic bath, magnetic stirrer and folded filters
Details on test solutions:
Pre-treatment of the test item
To produce the only Effective Loading, a Water Accommodated Fraction (WAF) was prepared. 20 mg of the test item were added directly to 2 litres of dilution water, treated for 1 hour in an ultrasonic bath and stirred for 24 h on a magnetic stirrer. Finally undissolved particles of the test item were removed by filtration using a folded filter with a pore size of 7 – 12 µm. The pH was measured and ranged between 7.8 and 8.0.
Test organisms (species):
Daphnia magna
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
21 d
Hardness:
14.5 - 15.4 °dH
Test temperature:
20.2 - 20.9 °C
pH:
7.9 - 8.1
Dissolved oxygen:
8.4 - 8.9 mg/L
Nominal and measured concentrations:
Nominal concentration: 10 mg/L (verified by DOC determination)
Details on test conditions:
- Test vessels: 150 mL glass beakers covered with watch glasses, holding 1 neonate in 100 mL of test medium
- Experimental design: 1 Effective Loading plus 1 control; 1 neonate per vessel, 10 replicates per Loading/control; Semi-static system (renewal of the test media on Monday, Wednesday and Friday)
- Method of initiation: neonates were placed in prepared media
- Photoperiod: 16 h light: 8 h dark
- Light intensity: not exceeding 15 - 20 µE x m-2 x s-1
- Temperature of incubation unit: 19.2 to 20.4 °C
- Aeration: none
- Test item concentration/s: 10 mg/L (nominal)
- Food source: Desmodesmus subspicatus
- feeding rate: day 0 - 7: 0.1 mg C / Daphnia / day; day 8 - 21: 0.2 mg C / Daphnia / day
- Duration of exposure: 21 days
- Criteria of effects: The criterion of adverse effects used in this study was the item-induced inhibitory effect on the parthenogenetic reproduction rate and the mobility behaviour/mortality rate of parent Daphnia, all effects being assessed at least three times a week.
Duration:
21 d
Dose descriptor:
other: NOEL
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
other: LOEL
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
1st brood on day: 8

No toxic effects against daphnia were observed at a limit Effective Loading of 10 mg/L.

The results are expressed in terms of Effective Loadings (EL).

The test item is insoluble or only poorly soluble in water. Additionally, it hydrolyses in a very short time. Therefore a suitable selective and sensitive chromatographic method for the determination of the test item in aqueous solutions could not be established. A Water Accommodated Fraction (WAF) was used to test effects at limit effective loading and no specific analysis was performed. With the sponsor’s agreement, the content of the test item during the exposure period was verified by DOC determination.
Reported statistics and error estimates:
All values were calculated using the statistics programme ToxRatPro Version 2.10 (released 2010-09-10).
Validity criteria fulfilled:
yes
Remarks:
mortality rate of controls ≤20 % by the end of test; mean number of live offspring produced per parent Daphnia surviving at the end of test was ≥60 in controls; DOC >3 mg/L throughout exposure period; pH within 6 - 9; dH >140 mg/L (as CaCO3)
Conclusions:
A study was performed to assess adverse effects of a limit concentration of the test item on the reproductive output of parthenogenetic Daphnia magna STRAUS under semi-static conditions within a 21 day exposure period under semi-static conditions. No toxic effects against daphnia were observed at a limit Effective Loading of 10 mg/L.
The results are expressed in terms of Effective Loadings (EL).
Executive summary:

A study was performed to assess adverse effects of a limit concentration of the test item on the reproductive output of parthenogenetic Daphnia magna STRAUS conditions according to the Council Regulation (EC) No 440/2008, Method C.20 'Daphnia magna Reproduction Test'' (2008), which equals to the OECD Test guideline 211 (Daphnia magna Reproduction Test; adopted: Oct. 02, 2012) within a 21 day exposure period under semi-static conditions.

An acute Daphnia toxicity test preceded the test of this report. It provided information about the range of concentrations to be applied in the reproduction test (see CURRENTA Study 2010/0045/10).

In the reproduction test, young female Daphnia, aged less than 24 hours at the start of the test, were exposed to the test item added to water at a limit Effective Loading of 10 mg/L (nominal) for a period of 21 days. This loading showed no reduction of the parthenogenetic reproduction rate over a 21 day study period. The living offspring was counted three times a week along with the renewal of the test medium (usually on Monday, Wednesday and Friday). However, test vessels were inspected daily for the occurrence of juveniles and marked accordingly. When juveniles in these marked vessels were counted the next day (or after the weekend), the number of offspring was assigned to the previous day when juveniles were first observed. Additionally, the survival of the parent Daphnia and the time to production of first brood was determined.

During the test a temperature range of 18 - 22 °C was maintained in the test vessels, with a maximum temperature fluctuation of +/- 2 °C in each individual test. Test vessels were not aerated during the test. A photoperiod of 8 hours darkness and 16 hours light was maintained, the light intensity not exceeding 15 – 20 µE x m 2 x s-1.

Feeding of the Daphnia with living cells of Desmodesmus subspicatus was done daily. The ration was 0.1 – 0.2 mg C / Daphnia / day which was regarded sufficient for achieving the required number of offspring in the controls.

The reproductive output of the Daphnia exposed to the test item was compared to that of the control in order to determine the Lowest Observed Effective Loading (LOEL) and the No Observed Effective Loading (NOEL) according to STUDENT-t test for Homogeneous Variances. All values were calculated using the statistics programme ToxRatPro Version 2.10 (released 2010-09-10).

Results [mg/L]:

21d-NOEL (reproduction) (tα 0.05): ≥10 mg/L

21d-LOEL (reproduction) (tα 0.05): >10 mg/L

21d-NOEL (mortality) (tα 0.05): ≥10 mg/L

21d-LOEL (mortality) (tα 0.05): >10 mg/L

1st brood on day: 8

No toxic effects against daphnia were observed at a limit Effective Loading of 10 mg/L.

The results are expressed in terms of Effective Loadings (EL).

The test item is insoluble or only poorly soluble in water. Additionally, it hydrolyses in a very short time. Therefore a suitable selective and sensitive chromatographic method for the determination of the test item in aqueous solutions could not be established. A Water Accommodated Fraction (WAF) was used to test effects at limit effective loading and no specific analysis was performed. With the sponsor’s agreement, the content of the test item during the exposure period was verified by DOC determination.

Description of key information

A study was performed to assess adverse effects of a limit concentration of the test item on the reproductive output of parthenogenetic Daphnia magna STRAUS under semi-static conditions within a 21 day exposure period under semi-static conditions. No toxic effects against daphnia were observed at a limit Effective Loading of 10 mg/L.

The results are expressed in terms of Effective Loadings (EL).

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
10 mg/L

Additional information

Should read ≥10 mg/L.