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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:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 200mg of 3-methoxy-3-methyl-1-butanol was placed into a 200mL measuring flask, and diluted with dilution water to prepare 1000mg/L of test stock solution, and a certain amount of this solution was placed into a 1L measuring flask and diluted with dilution water to be the test solution.

- Controls: yes (no specification mentioned).
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: National Institute for Environmental Studies, Ministry of the Environment
- Feeding during test
- Food type: Chlorella vulgaris
- Amount: 0.15-0.2mgC (organic carbon)/flea/day
- Frequency: daily
-other: kept at room light, 16-8 hour light-dark photocycle

ACCLIMATION
- Acclimation period: January 14, 2002 to February 8, 2002 (of parental Daphnia)
- Acclimation conditions (same as test or not): same
- Health during acclimation (any mortality observed): The mortality rate of the parental Daphnia in two weeks before exposure was 5% or less, and there were no production of resting eggs or males


METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
- Juveniles were used for testing within 24 hours of birth.
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
21 d
Hardness:
249-281mg/L
Test temperature:
20.3-20.8
pH:
7.2-8.3,
Dissolved oxygen:
7.0-8.2mg/L
Nominal and measured concentrations:
10, 22, 46 and 100mg/L of MMB. The measured concentrations were within ±20% of the nominal values.
Details on test conditions:
TEST SYSTEM
- Test vessel: 100mL screw glass tubes, including 80 mL test solution.
- Renewal rate of test solution (frequency/flow rate): The total volumes of the test solutions were replaced three times per week (Monday, Wednesday and Friday)
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4, artificially prepared water was used. Source not stated in report.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16-8 hour light-dark photocycle

VEHICLE CONTROL PERFORMED: no (no vehicle was used)

RANGE-FINDING STUDY
- Test concentrations: An 48-hour acute immobilization concentration was 1000mg/L or more, and therefore, starting from 100mg/L, four test concentrations were set in decreasing order, using 2:2 of common ratio.
Each concentration group is shown below;
10, 22, 46 and 100mg/L concentration/control groups were set.
Reference substance (positive control):
yes
Remarks:
potassium bichromate, EC50 value at testing site was within 0.49-1.01mg/L, n=5.
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L

-Effect Data:
      LC50 (21day) >100 (nc)
       EC50 (21day) >100 (nc)
      NOEC (21day) = 100 (nc)
      LOEC (21day) > 100 (nc)
      nc: based on the nominal concentrations


- Cumulative Number of Died Parental Daphnids: No test
organism died at any concentration.
-----------------------------------------------------------
Nominal      Cumulative Number of Dead Parental Daphnids
Conc.                             (days)
(mg/L)   1   2   3   4   5   6   7   8   9   10
-----------------------------------------------------------
Control  0   0   0   0   0   0   0   0   0    0
10       0   0   0   0   0   0   0   0   0    0
22       0   0   0   0   0   0   0   0   0    0
46       0   0   0   0   0   0   0   0   0    0
100      0   0   0   0   0   0   0   0   0    0
-----------------------------------------------------------
-----------------------------------------------------------
Nominal   Cumulative Number of Dead Parental Daphnids
Conc.                             (days)
(mg/L)  11  12  13  14  15  16  17  18  19  20  21
-----------------------------------------------------------
Control  0   0   0   0   0   0   0   0   0   0   0
10       0   0   0   0   0   0   0   0   0   0   0
22       0   0   0   0   0   0   0   0   0   0   0
46       0   0   0   0   0   0   0   0   0   0   0
100      0   0   0   0   0   0   0   0   0   0   0
-----------------------------------------------------------

-Effect Data(reproduction):Juveniles were first produced
between the 8th to 10th day at every concentration.
-----------------------------------------------------------
Nominal               Mean Cumulative Numbers of
Conc.              Juveniles Produced per Adult (days)
mg/L    0 --- 7    8    9     10     11    12   13    14
-----------------------------------------------------------
Control 0 --- 0    0    1.3   7.2   8.5   10.5  20.8  24.4
10      0 --- 0   1.6   3.5   5.3   10.2  13.0  15.3  26.2
22      0 --- 0   2.6   3.6   6.8   12.8  14.6  21.2  34.3
46      0 --- 0   1.0   1.4   7.7   10.2  11.2  22.7  27.8
100     0 --- 0    0    0.4   7.4    8.7  9.6   22.1  25.8
-----------------------------------------------------------
-----------------------------------------------------------
Nominal        Mean Cumulative Numbers of
Conc.      Juveniles Produced per Adult (days)
mg/L     15     16     17      18      19     20     21
-----------------------------------------------------------
Control  25.2   36.4   43.1    44.9    54.2  63.6   64.9
10       26.8   29.6   48.4    50.4    53.6  66.7   71.2
22       34.3   42.6   63.4    63.4    72.2  88.3   90.0
46       28.7   43.1   50.7    52.1    66.1  72.4   73.9
100      25.8   41.5   47.0    47.0    64.9  69.4   70.0
-----------------------------------------------------------

-Cumulative numbers of juveniles produced per adult alive
for 21days in each test vessels and results of statistical
comparison of the mean values (by Dunnett's Multicomparison
Test) 
-----------------------------------------------------------
                Nominal Conc., mg/L
-----------------------------------------------------------
Vessel No.    Control   10    22   46   100
-----------------------------------------------------------
1               52     102    84   73   90
2               41      93   120   59   27
3               32      78    74   83  106
4               60      56   104   93   86
5               80      31    61   52   85
6               80      98    96   78   86
7               82      41    80   87   94
8               55      63    98  108   27
9               71      55    96   77   64
10              96      95    87   29   35
-----------------------------------------------------------
Mean            64.9  71.2  90.0  73.9  70.0
S.D.            20.3  25.5  16.6  22.4  29.8
-----------------------------------------------------------
Inhibition rate(%)   -9.7  -38.7  -13.9  -7.9
Significant difference  N.S.  N.S.  N.S.  N.S.
-----------------------------------------------------------


- Calculation of toxicity values: The calculation of
toxicity values was the nominal concentrations.

DUNNETT method was used as a statistical method.

Validity criteria fulfilled:
not specified
Conclusions:
In this test, the 21-day EC50, LC50 and LOEC50 of MMB towards daphnia magna were determined to be > 100 mg/L.
The NOEC was 100 mg/L.

Description of key information

A 21 d daphnia magna NOEC of 100 mg/L was determined for MMB.

Key value for chemical safety assessment

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

Additional information