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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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well conducted with standard guidelines and chemical analysis. No GLP no analytical certificates and no raw data.
Qualifier:
according to guideline
Guideline:
other: ASTM E 1295-01 (2002)
Principles of method if other than guideline:
Three-brood survival/reproduction bioassays were performed according to the above mentioned guideline.
Long-term measurement of reproduction rate was performed as follows. Organisms were cultured according to US EPA methods with the only modification being that the culture water contained an elevated sodium sulfate concentration of 1000 mg SO4 2-/l. Cultures were initiated simultaneously using the same cohort of neonates produced by animals cultured in MHRW. Neonates to start a new generation were selected from animals that had produced at least three broods and had not reproduced on the previous day. Five generations were cultured in each treatment.
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
No details given
Vehicle:
no
Details on test solutions:
Three-brood survival/reproduction bioassays: six sulfate concentrations, including a control
Long-term measurement of reproductive rate (5 generations): control, 1000 mg SO4 2-/l
Test organisms (species):
Ceriodaphnia dubia
Details on test organisms:
TEST ORGANISM
- Source: in-house culture according to US EPA methods. Initially obtained from Aquatic Research Organisms, Hampton, NH
- Age at study initiation: less than 24h
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Remarks on exposure duration:
differs per test
Hardness:
92 ± 2 mg CaCO3/l
pH:
8.0 ± 0.1
Details on test conditions:
Three-brood survival/reproduction bioassay:

TEST SYSTEM
- Test vessel:
- Type: open
- Material, size, headspace, fill volume: 50 ml glass beakers
- Renewal rate of test solution (frequency/flow rate): daily
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10
- Feeding: as in culture according to US EPA methods

TEST MEDIUM / WATER PARAMETERS
- Type of water: Moderately Hard Reconstituted Water (MHRW) and Reformulated Moderately Hard Reconstituted Water (RMHRW)
RMHRW had similar hardness but a different Ca:Mg ratio and chloride concentration from MHRW.

TEST DURATION
Until at least 60% of the test organisms had produced three broods. This was 7 days in all cases.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): number of young and survival of parent animals were counted daily.


Long-term measurement of reproductive rate:

TEST SYSTEM
- Test vessel:
- Type: open
- Material, size, headspace, fill volume: 50 ml glass beakers
- Renewal rate of test solution (frequency/flow rate): daily
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 20
- No. of vessels per control (replicates): 20
- Feeding: as in culture according to US EPA methods

TEST MEDIUM / WATER PARAMETERS
- Type of water: Moderately Hard Reconstituted Water (MHRW)

TEST DURATION
Five generations

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): total number of neonates produced per animal after 8 days. Neonates were counted and removed daily.
Reference substance (positive control):
no
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
1 329 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Test medium is MHRW
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
1 698 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Test medium is MHRW
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
3 277 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Test medium is MHRW
Duration:
7 d
Dose descriptor:
LC50
Effect conc.:
3 030 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Test medium is MHRW
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
1 828 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Test medium is RMHRW
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
2 156 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: Test medium is RMHRW
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
4 436 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Test medium is RMHRW
Duration:
7 d
Dose descriptor:
LC50
Effect conc.:
3 611 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Test medium is RMHRW
Details on results:
From a graph it can be seen that the lowest test concentration of approx. 1109 mg/l (which is given in the graph as 750 mg SO4 2-/l) did not give a significant effect, therefore 1109 mg/l can be taken as the NOEC.

Long-term measurement of reproductive rate:
C. dubia cultured in 1000 mg SO4 2-/l produced significantly fewer neonates than in the control.
Combining the 5 generations the overal mean number of neonates produced per animal after 8 days in MHRW was 62.2 ± 6.6 and for MHRW with 1000 mg SO4 2-/l it was 50.6 ± 5.3.
Reported statistics and error estimates:
Three-brood survival/reproduction bioassay:
Three tests were conducted in each water type to obtain average values for percent survival and reproduction. For survival Fisher's Exact test was used to compare treatments to controls and for reproduction Dunnett's test was used.

Long-term measurement of reproductive rate:
Repeated-measures ANOVA was used to test the difference between the treatment and control, and if that difference varied from generation to generation.

The results in the publication are given as mg sulfate ion, these values were converted to mg sodium sulfate.

It is not known whether nominal or measured concentrations are use for the results. It is written that analyses were performed to confirm sulphate concentrations, but no details are given in the publication whether or not measured concentrations were similar to nominals.

Validity criteria fulfilled:
not specified
Conclusions:
Sodium sulfate is not toxic to C. dubia in the long-term experiments. The LOEC for reproduction in MHRW was 1329 mg/l, which was the lowest result obtained in this test. The NOEC (taken from a graph) is 1109 mg/l.
Over 5 generations reproduction was significantly lower in 1000 mg SO4 2-/l compared to the control.
The test was found to be valid with restrictions because the study was well conducted with standard guidelines and chemical analysis. No GLP no analytical certificates and no raw data were documented.
Executive summary:

Three-brood survival/reproduction bioassays were performed according to standard ASTM guidelines. Mortality and reproduction were checked daily and LOEC-, LC50- and EC50 values were determined.

Long-term measurement of reproduction rate was performed as follows. Organisms were cultured according to US EPA methods with the only modification being that the culture water contained an elevated sodium sulfate concentration of 1000 mg SO4 2-/l. Cultures were initiated simultaneously using the same cohort of neonates produced by animals cultured in MHRW. Neonates to start a new generation were selected from animals that had produced at least three broods and had not reproduced on the previous day. Five generations were cultured in each treatment.

Sodium sulfate is not toxic to C. dubia in the long-term experiments. The LOEC for reproduction in MHRW was 1329 mg/l, which was the lowest result obtained in this test. The NOEC (taken from a graph) is 1109 mg/l.

Over 5 generations reproduction was significantly lower in 1000 mg SO4 2-/l compared to the control.

Description of key information

A 7d-LOEC of 1329 mg/Lwas obtained concerning the reproduction of Ceriodaphnia dubia exposed to sodium sulfate. The NOEC on the reproduction was estimated graphically at 1109 mg/L. Sodium sulphate is not toxic regarding the reproduction of Ceriodaphnia dubia, and according to CLP criteria, it is not classified for long-term aquatic toxicity on invertebrates.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
1 109 mg/L

Additional information

Three-brood survival/reproduction bioassays were performed according to standard ASTM guidelines. Mortality and reproduction were checked daily and LOEC-, LC50- and EC50 values were determined.

Long-term measurement of reproduction rate was performed as follows. Organisms were cultured according to US EPA methods with the only modification being that the culture water contained an elevated sodium sulfate concentration of 1000 mg SO4 2-/l. Cultures were initiated simultaneously using the same cohort of neonates produced by animals cultured in MHRW (Moderate Hardness Reconstituted Water). Neonates to start a new generation study were selected from animals that had produced at least three broods previously and had not reproduced on the previous day. So five generations were cultured in each treatment.

Sodium sulfate is not toxic to Ceriodaphnia dubia in the long-term experiments. The LOEC for reproduction in MHRW was 1329 mg/l, which was the lowest result obtained in this test. The NOEC (taken from a graph) is 1109 mg/l.

Over 5 generations, reproduction was significantly lower in 1000 mg SO4 2-/l compared to the control.

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