Calcium

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

supporting study

Study period:

19 - 21 June 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Reliability for the original study report: 1 (reliable without restriction). Rationale: GLP study, according to the OECD 202 guideline. For read-across purpose reliability rating 2 was considered applicable.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

Although the pH increased significantly, it was not neutralized.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Calcium dihydroxide

EC Number:

215-137-3

EC Name:

Calcium dihydroxide

Cas Number:

1305-62-0

Molecular formula:

CaH2O2

IUPAC Name:

calcium dihydroxide

Details on test material:

Test item: PRECAL 50S
Active ingredient: Calcium dihydroxide
Batch no.: 7025
Content: 98.2% (w/w)
Physical appearance: white powder
Water solubility: 1.26 g/l (20°C)
Date of receipt/quantity received: Jan. 31, 2007 / approx. 2 kg
Storage requirements: store under dry conditions, tightly closed
Stability under correct storage conditions / expiry date: January 30, 2009

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Control, and all test solutions were sampled in duplicate. The duplicate sample was kept separately as a reserve. Immediately after sampling, the samples were superposed with nitrogen.

Test solutions

Vehicle:

not specified

Details on test solutions:

Elendt Medium M4 was used to dilute the test item and to keep the daphnids during the period of the test. The preparation of medium M4 is described in the Standard Operation Procedure (SOP) A 5.6.
The required amount of Medium M4 was prepared not longer than 4 weeks before it was used.
During storage Medium M4 was aerated.
CHARACTERISTICS OF THE BATCH MEDIUM M4:
Water hardness: 250 mg/l as CaCO3.
pH: 7.6
Temperature: 21.3 °C
Dissolved oxygen: 98%
Dissolved oxygen: 8.6 mg/l
Conductivity: 600 μS/cm

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna (Straus), clone 5, cultured at ECT Oekotoxikologie GmbH since October 11, 2000.
The organisms were originally supplied by Aventis, Frankfurt a.M.
The age of the daphnids at the beginning of the test: 6 - 24 h.
CULTURING OF DAPHNIA MAGNA:
Material of stock vessel: glass
Amount of medium per stock vessel: 1.8 l
Depth of medium in the stock vessel: 14 - 15 cm
Number of daphnids kept as stock per culture vessel: approximately 20
Separation of adult and young daphnids: 1 to 4 times per week
Medium: medium M4
Renewal of medium: approximately 2 times per week
Temperature: 20 ± 2°C
Photoperiod (light/dark): 16/8 h
Light intensity: 50 - 1000 lx
Aeration: none
Food: Algae (Desmodesmus subspicatus, Pseudokirchneriella subcapitata), TetraMin, instant baker's yeast suspension
Feeding frequency: 3 times a week
One day before starting the exposure, all young daphnids were removed from selected holding vessels which contained adult daphnids aged 15 to 45 days. Al least 6 hours before placing young daphnids
into the test vessels the newborn daphnids were separated from the parental daphnids which were kept in the selected holding vessels.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

not applicable

Test conditions

Hardness:

250 (mean) mg/l CaCO3

Test temperature:

19.1-21.7°C

pH:

7.7-11.1

Dissolved oxygen:

8.5-8.7 mg/l O2

Salinity:

not applicable

Nominal and measured concentrations:

Nominal: 0.0, 14.8, 22.2, 33.3, 50.0 and 75.0 mg/l.

Details on test conditions:

Number of replicates per test concentration: 4
Number of organisms per test vessel: 5
Test units: 300 ml glass beaker, covered by glass lids
Amount of test solution per test vessel: 150 - 200 ml
Test medium: Medium M4
Aeration of test vessel: none
Adjustment of pH in the test solutions: none
Renewal of the rest solution during the test: none
Feeding during exposure: none
Light regimen: 16 h light : 8 h dark
Light intensity: 354 lx (247 - 453 lx)

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC50

Remarks:

from regression curve

Effect conc.:

49.1 mg/L

Nominal / measured:

estimated

Conc. based on:

act. ingr.

Remarks:

Ca(OH)2

Basis for effect:

mobility

Remarks on result:

other: calculated pH 10.9

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

33.3 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Remarks:

Ca(OH)2

Basis for effect:

mobility

Remarks on result:

other: initial pH 10.1

Effect concentrations 3

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

75 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Remarks:

Ca(OH)2

Basis for effect:

mobility

Remarks on result:

other: initial pH 11.1

Details on results:

- Behavioural abnormalities: some daphnids sticking to the water surface were observed at all concentrations, except the control and the highest test concentration. Daphnids with reduced swimming
activities compared to controls were observed at the 50 mg/L level.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: with increasing test item concentrations, precipitates formed over time. The formation of
precipitates is likely the result of the reaction between Ca(OH)2 and CO2 dissolved in the medium yielding poorly soluble CaCO3.

Results with reference substance (positive control):

24h-EC50 is 2.06 mg/L, which is in the range between 0.6 and 2.1 mg/L (OECD, April, 2004). Therefore the results with the reference substance are acceptable.

Any other information on results incl. tables

Initial pH values: 7.7 (control), 9.5 (14.8 mg/L), 9.7 (22.2 mg/L), 10.1 (33.3 mg/L), 10.7 (50 mg/L) and 11.1 (75 mg/L). Using nonlinear regression analysis of the initial OH- concentration against the % inhibition, resulted in an equation (r2=0.992) from which the EC50 was derived: OH- concentration of 0.000717 mol/L (i.e. 49.1 mg/L) and pH 10.9.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Immobilised daphnids in the control: 0%. Dissolved oxygen concentration at the end of the test in control and test vessels: 8,5 mg/l.

Conclusions:

A clear concentration-response relationship was observed.
The biological findings (immobilisation of the daphnids) were closely related to the initial pH and the corresponding OH- concentrations in the test solutions. At the test item concentration used in this study,
the pH values were in the range of the control pH within 24 hours. Therefore the initial pH is considered to be the main reason for the effects of the test item on the test organisms.