Barium oxide, obtained by calcining witherite

Long-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Not conducted according current guideline but study well documented and meeting generally accepted scientific principles

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Effects of various metals on survival, growth, reproduction and metabolism of Daphnia magna

Author:

Biesinger K. E. and Christensen G. M.

Year:

1972

Bibliographic source:

Journal fisheries Research Board of Canada, Vol. 29 No. 12, 1972

Reference 2

Reference Type:

secondary source

Title:

Barium and Barium Compounds

Author:

World Health Organization

Year:

2001

Bibliographic source:

Concise International Chemical Assessment Document 33. World Health Organisation (Geneva)

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Barium chloride

EC Number:

233-788-1

EC Name:

Barium chloride

Cas Number:

10361-37-2

IUPAC Name:

barium dichloride

Sampling and analysis

Analytical monitoring:

not specified

Test solutions

Vehicle:

no

Details on test solutions:

The number of concentrations tested ranged from 5 to 12 dependent on the toxicant and the initial effects observed.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

- Strain: laboratory clone
- Source: University of Michigan
- Age at study initiation (mean and range, SD): 12h +/- 12h

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Test conditions

Hardness:

Mean: 45.3 mg/L (Range: 44.0 - 53.0)

Test temperature:

18 +/- 1 °C

pH:

Mean: 7.74 (Range: 7.4 - 8.2)

Dissolved oxygen:

Near saturation

Details on test conditions:

Five Daphnids were placed in 200 mL of water in 250-mL beaker. Four beaker (the test chambers) were used with a total of 20 animals for each experimental and control condition for each test. The test chambers were covered with a pane of glass to minimize evaporation and distributed randomly in a constant temperature room.. Young daphnids were placed in test chambers into new medium at the beginning of each week and subjected to test conditions for 3 weeks. Survival of the initial animals was noted after1, 2 and 3 weeks. At the end of three weeksthe surviving animals were weighed and prepared for protein and GOT analyses. Reproduction was assessed by counting the young produced each week. Light intensity of about 115 ft-c at the water interface was provided. An automatically controlled16-hr photoperiod was used.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

8.9 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

reproduction

Effect concentrations 2

Duration:

21 d

Dose descriptor:

other: EC16

Effect conc.:

5.8 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

reproduction

Reported statistics and error estimates:

Results were statistically evaluated with the method of Lichtfield and Wilcoxon (1949) for establishing appoximations of the 95% confidence limit for survival. Reproductive effects were analyzed in a similar manner excluding confidence limits, but are given in terms of reproductive impairment by percentage. Both 50% and 16% reproduction-impairments are given. These values imply decreases in the total number of youngproduced as compared with the control. The 16% reproductive-impairment concentration is given since it represented a minimal reproducible value below which the variability in reproduction could not be detected from controls.