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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:
other information
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: National Institute for Environmental Studies (Japan)
- Pretreatment of parent: 2-3 weeks
- Age at study initiation: less than 24 h old

ACCLIMATION
- Acclimation period: yes
- Acclimation conditions: same as test
- Type and amount of food: 0.1-0.2 mgC/day/daphnia
Test type:
semi-static
Water media type:
freshwater
Total exposure duration:
21 d
Hardness:
238-249 mg/l as CaCO3
Test temperature:
19.9 - 20.9 °C
pH:
6.8 - 7.4
Dissolved oxygen:
7.3 - 8.6 mg/l
Nominal and measured concentrations:
concentration (nominal): 0, 2.4, 3.8, 6.1, 9.8, 15.6, 25.0 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- glass vessel, 100 ml net volume with 80 ml solution
- Aeration: none
- Renewal rate of test solution: 3 times a week
- Feeding during test: Chlorella regularis, 0.1-0.2 mgC/day/daphnia
- No. of organisms per vessel: 1 daphnia
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): no data

TEST MEDIUM / WATER PARAMETERS
- Source of dilution water: Elendt M4 (in accordance with OECD TG211 Annex 2)
- pH: 7.0
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no data
- Photoperiod: 16h-8h light-dark cycle by room light
- Light intensity: no data
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
15.8 mg/L
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
7.6 mg/L
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
13.3 mg/L
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
other: 21day LC50
Effect conc.:
17.4 mg/L
Basis for effect:
other: mortality of parent daphnid
Results with reference substance (positive control):
Potassium dichromate (48hr EC50 = 0.90 mg/L)
CONCENTRATIONS
nominal            measured concentration (mg/l) (% of nominal)
concentration  0day   2day   7day   9day  14day  16day   21day
  (mg/L)       new    old    new    old    new    old     mean
-----------------------------------------------------------
control        <0.1   <0.1    <0.1   <0.1    <0.1   <0.1
  2.4          1.6     0.9     1.7    0.9     1.9    1.0    1.3
             (66.7)  (37.5)   (70.8)  (37.5)   (79.2)  (41.7)  (53.8)
  3.8          2.4     1.3     2.7    1.4     3.0    1.5    2.0
             (63.2)  (34.2)   (71.1)  (36.8)   (78.9)  (39.5)  (52.6)
  6.1          3.5     2.2     4.4    2.3     4.8    2.5    3.2
             (57.4)  (36.1)   (72.1)  (37.7)   (78.7)  (41.0)  (52.5)
  9.8          5.5     3.7     7.0    3.5     7.7    4.1    5.1
             (56.1)  (37.8)   (71.4)  (35.7)   (78.6)  (41.8)  (52.0)
 15.6          8.9     6.1     8.4    4.4    12.3    6.8    7.6
             (57.1)  (39.1)   (53.8)  (28.2)   (78.8)  (43.6)  (48.7)
 25.0         13.7    10.7    18.3    8.9    19.8   10.8    13.3
             (54.8)  (42.8)   (73.2)  (35.6)   (79.2)  (43.2)  (53.2)
-----------------------------------------------------------
rem. new = fresh solution
     old = expired solution
     mean = time-weighted mean during 21 days
As the half-life of this substance in water is 56.7 h at 25 °C and pH 7  (See section 3.1.2), almost all measured concentrations were much lower  than the nominal ones. Therefore, time-weighted mean measured values were  used for calculations.

EFFECTS
21day LC50 = 17.4 mg/l (95% confidendential: 8.8-1315 mg/l)
21day EC50 = 15.8 mg/l (95% confidendential: 13.6-19.4 mg/l)
21day NOEC = 7.6 mg/l
21day LOEC = 13.3 mg/l

CUMULATIVE NUMBER OF DEAD PARENTAL DAPHNIA AND THE MORTALITY AFTER 21 DAYS
measured concent-   number of     mortality
ration (mg/l)        dead parent       %
----------------------------------------------------------
control                 0             0
  1.3                   2            20
  2.0                   0             0
  3.2                   0             0
  5.1                   1            10
  7.6                   1            10
 13.3                   7            70
----------------------------------------------------------

TIME (DAY) TO FIRST BROOD PRODUCTION
measured concent-    mean
ration (mg/l)          (day)
-----------------------------------------
control               8.3
  1.3                 7.1
  2.0                 8.2
  3.2                 7.6
  5.1                 7.2
  7.6                 7.6
 13.3                 7.9
-----------------------------------------

MEAN CUMULATIVE NUMBER OF JUVENILES PRODUCED PER ADULT DURING 21 DAYS  EXPOSURE
measured concent-  mean (mumber
ration (mg/l)         of juveniles)
-------------------------------------------------
control               148.8
  1.3                 148.4
  2.0                 138.3
  3.2                 138.7
  5.1                 145.4
  7.6                 140.8
 13.3                  68.0
-------------------------------------------------

Conclusions:
The EC50 (21 days reproduction) for Daphnia magna is 15.8 mg/l.
The NOEC (21 days reproduction) for Daphnia magna is 7.6 mg/l.
The LOEC (21 days reproduction) for Daphnia magna is 13.3 mg/l.

Description of key information

The EC50 (21 days reproduction) for Daphnia magna is 15.8 mg/l.
The NOEC (21 days reproduction) for Daphnia magna is 7.6 mg/l.
The LOEC (21 days reproduction) for Daphnia magna is 13.3 mg/l.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Dose descriptor:
NOEC
Effect concentration:
7.6 mg/L

Additional information