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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)
Version / remarks:
1998
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
50 ml water samples for concentration measurement of m-toluic acid were taken. The test concentrations were measured for both renewal and old test solution at the start of test and 2nd, 6th 8th, 14th and 16th day.
Vehicle:
no
Details on test solutions:
A stock solution was prepared in dechlorinated tap water. No further information given.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Source: Test organisms were obtained from the National Institute for Environmental Studies (Japan)
- Age of parental stock: 2-4 weeks
- Age at test initiation: < 24 h
- Feeding during test
- Food type: Chlorella vulgaris
- Amount/Frequency: approx. 0.15 mg C (organic carbon) per daphnia per day
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
87-88 mg/L
Test temperature:
19.2 - 20.8 °C
pH:
6.8 - 8.2
Dissolved oxygen:
7.6 -9.6 mg/L
Nominal and measured concentrations:
Nominal concentrations: 0 (control), 1.0, 2.2, 4.6, 10, 22 and 46 mg/L

- Low concentration 1.0 mg/L: The test was carried out three times in parallel, the recovery rate was 100.7%, 99.7%, 100.8% (average 100.4%).
- High concentration 46.0 mg/L: The test was carried out three times in parallel, the recovery rate was 100.1%, 98.3%, 98.6% (average 99.0%).
Details on test conditions:
TEST SYSTEM
- Test vessel:100 mL glass jar with glass screw cap filled with 80 mL test solution
- Renewal rate of test solution (frequency/flow rate): every 48 h
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dechlorinated tap water

OTHER TEST CONDITIONS
- Photoperiod: 16:8 hours, light-darkness


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
reproduction rate

Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
9.7 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
22 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
15 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LC50
Effect conc.:
> 46 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 46 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
Calculated based on measured concentrations, because some of the measured concentration were less than 80% of the nominal.

NOEC or LOEC was determined based on the cumulative number of juveniles produced per adult alive for 21 days. 1.0 and 2.2 mg/L indicate a significant difference from the control by Dunnett type multiple comparisons procedure, one-side test. However these results were judged that there was nothing under the influence by this substance because no significant difference at 4.6 and 10 mg/L.
Results with reference substance (positive control):
The test was carried out with potassium dichromate, EC for 48 hours was 0.49 mg /L (carried out on November 17, 1999) and 0.75 mg /L
(Implemented on May 16, 2000).
Reported statistics and error estimates:
a) Data Analysis: Dunnett multiple comparison for NOEC and LOEC
b) Method of Calculating Mean Measured Concentrations: Arithmetic Mean or Time-weighted Mean

Table 1: Cumulative numbers of juveniles produced per adult alive for 21 days

Vessel No. Cont. 1 (0.542) 2.2 (1.5) 4.6 (4.12) 10 (9.74) 22 (22.1) 46 (45.9)
1 121 122 117 109 122 3 0
2 103 98 100 115 103 8 0
3 110 105 118 111 117 3 0
4 110 94 103 112 110 5 0
5 114 111 100 114 98 6 0
6 129 110 106 113 115 7 0
7 116 104 120 108 120 3 0
8 116 106 102 107 113 4 0
9 106 112 96 113 119 2 0
10 118 104 108 114 107 2 0
Mean 114.3 106.6 107 111.6 112.4 4.3 0
S.D. 7.6 7.8 8.5 2.8 7.8 2.1 0
Inhibition rate (%) -- 6.7 6.4 2.4 1.7 96.2 100
Significant difference*1 -- * * NS NS ** --

*1: Indicates a significant difference from the control by Dunnett type

multiple comparisons procedure, one-side test.

*: Significant (p<0.05)

**: Significant (p<0.01)

NS: Not significant (p>=0.05)

Table 2: Cumulative number of died parental daphnids

Nominal Conc. (mg/L) Cumulative Number of Died Parental daphnids (days)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Control 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2.2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
4.6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
22 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
46 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Validity criteria fulfilled:
yes
Conclusions:
Daphnia magna neonates (< 24 h old) were exposed to m-toluic acid in dechlorinated tap water in a GLP-conform chronic reproduction test according to OECD TG 211. Mortality was not observed in the control or at any of the tested concentrations (LC50 >46 mg/L; NOEC >= 46 mg/L). A reduction of offsprings was observed at 22 mg/L (LOEC) after 21 days; the corresponding NOEC amounts to 9 mg/L (all measured TWA).

Description of key information

In a GLP-conform OECD 211 chronic reproduction test with Daphnia magna, effects on reproduction were observed at 22 mg m-toluic acid/L. The corresponding NOEC amounts to 9.7 mg/L m-toluic acid (measured).

Key value for chemical safety assessment

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

Additional information