Sodium sulphate

Long-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Literature data, well conducted

Data source

Reference

Reference Type:

publication

Title:

Bioenergetic effects of sodium sulfate on the freshwater crustacean, Ceriodaphnia dubia

Author:

Soucek David J.

Year:

2007

Bibliographic source:

Ecotoxicology (2007) 16:317–325

Materials and methods

Principles of method if other than guideline:

To investigate the long-term, generational effects of exposure to sodium sulfate on C. dubia fecundity, organisms were cultured according to U. S. EPA (2002) methods. The concentration of 1000 mg/L was selected because of its proximity to reproductive impairment thresholds generated in the three-brood chronic bioassays in MHRW. The endpoint evaluated was the total number of neonates produced per female after 8 days (usually three or four broods per female). Because C. dubia neonates are clones, there is dependence between generations, thus the unit of measure was a clonal line.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Sodium sulphate

EC Number:

231-820-9

EC Name:

Sodium sulphate

Cas Number:

7757-82-6

Molecular formula:

H2O4S.2Na

IUPAC Name:

disodium sulfate

Test solutions

Details on test solutions:

Previous experiments indicated that the salts and deionized water sources used for experiments had low to undetectable levels of trace metal contaminants.
With the exception of conductivity, the addition of sodium sulfate to test solutions had a negligible effect on the above listed water quality parameters.
Samples from each experimental treatment were analyzed to confirm sulfate concentrations by ion chromatography at the Illinois Natural History Survey Aquatic Chemistry Laboratory, Champaign, IL, USA.

Test organisms

Test organisms (species):

Ceriodaphnia dubia

Details on test organisms:

TEST ORGANISM
- Reason of the choice: the cladoceran, Ceriodaphnia dubia, was selected as a test organism because of its ubiquitous use in the United States for regulatory permit testing, its greater sensitivity to contaminants compared to other cladocerans and the large base of data available on its response to other contaminants. Previous studies have demonstrated the repeatability of its response to sodium sulfate (Soucek and Kennedy 2005; Kennedy et al. 2005).
- Source: organisms were initially obtained from a commercial source (Aquatic Research Organisms, Hampton, NH) and then a continuous culture of the organisms initiated from a single female was maintained in the laboratory for at least 1 year prior to commencement of testing.
- Culture condiitons: cultured according to U. S. EPA (2002) methods with the only modification being that the culture water contained elevated sodium sulfate.

Study design

Test type:

semi-static

Water media type:

freshwater

Total exposure duration:

8 d

Test conditions

Hardness:

92 ± 2 mg/L as CaCO3

pH:

8.0 ± 0.1

Nominal and measured concentrations:

1000 mg/L

Details on test conditions:

TEST SYSTEM
- Generation: 5 generations cultured in each treatment (control, elevated sulfate).

TEST MEDIUM / WATER PARAMETERS
Tests were conducted in two different dilution waters: MHRW and a ‘‘reformulated MHRW’’ or RMHRW (Smith et al. 1997) which had a similar hardness and pH but different Ca:Mg ratio and chloride concentration. RMHRW was tested in addition to MHRW. Three tests were conducted in each water type to obtain average values for percent survival and reproduction.
- Alkalinity: 62 ± 2 mg/L as CaCO3
- Conductivity: 300 ± 7 µS/cm

END POINT EVALUATIONS: the endpoint evaluated was the total number of neonates produced per female after 8 days (usually three or four broods per female). Because C. dubia neonates are clones, there is dependence between generations, thus the unit of measure was a clonal line.

PREVIOUS TEST
The concentration of 1000 mg/L was selected because of its proximity to reproductive impairment thresholds generated in the three-brood chronic bioassays in MHRW. Control (MHRW) and treatment (MHRW + 1000 mg/L) cultures were initiated simultaneously using the same cohort of neonates produced by females cultured in MHRW. One adult organism was held in each of twenty 50-ml culture beakers, and neonates were counted and removed daily. Neonates to start a new generation were selected from a female that had produced at least three broods and had not reproduced on the previous day. After the first generation, only neonates produced in MHRW were used to start a new MHRW culture and likewise for the MHRW + 1000 mg/L treatment.

Results and discussion

Effect concentrations

Remarks on result:

not measured/tested

Any other information on results incl. tables

Organisms that either died due to technician error or did not reproduce at all (two out of 100 individuals in the MHRW and three out of 100 individuals in the MHRW + 1000 mg /L treatment) were excluded from analyses.

Ceriodaphnia dubia cultured in 1000 mg/L produced significantly fewer neonates than those cultured in MHRW according to the repeated measures ANOVA (F = 359.464, DF = 36, p < 0.0001 for treatment effect). In addition, sulfate affected C. dubia reproduction differently in different generations as both the generation term (F = 43.760, DF = 33, p < 0.0001) and the generation treatment interaction term (F = 4.018, DF = 33, p = 0.0092) were significant.

Separate pairwise analysis of treatment effects for each generation also indicated that C. dubia cultured in 1000 mg/L produced significantly fewer neonates after 8 days than controls (p < 0.0001 for each generation).

Combining the five generations, the overall mean (± standard deviation) number of neonates produced per female after 8 days in MHRW was 62.2 ± 6.6 (n = 98), and for the MHRW + 1000 mg/L it was 50.6 ± 5.3 (n = 97).

Applicant's summary and conclusion

Conclusions:

Ceriodaphnia dubia cultured in 1000 mg/L produced significantly fewer neonates than those cultured in MHRW. In addition, sulfate affected C. dubia reproduction differently in different generations as both the generation term and the generation treatment interaction term were significant.

Executive summary:

To investigate the long-term, generational effects of exposure to sodium sulfate on C. dubia fecundity, organisms were cultured according to U. S. EPA (2002) methods. The concentration of 1000 mg/L was selected because of its proximity to reproductive impairment thresholds generated in the three-brood chronic bioassays in MHRW.

The endpoint evaluated was the total number of neonates produced per female after 8 days (usually three or four broods per female). Because C. dubia neonates are clones, there is dependence between generations, thus the unit of measure was a clonal line.

Result

Ceriodaphnia dubia cultured in 1000 mg/L produced significantly fewer neonates than those cultured in MHRW. In addition, sulfate affected C. dubia reproduction differently in different generations as both the generation term and the generation treatment interaction term were significant.

Combining the five generations, the overall mean number of neonates produced per female after 8 days in MHRW was 62.2 ± 6.6 and for the MHRW + 1000 mg/L it was 50.6 ± 5.3.