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Short-term toxicity to fish

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short-term toxicity to fish
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
September 6, 2007 - September 10, 2007
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
GLP study according to OECD 203. No. of replicates per concentration used = 1. Rationale for read-across: in the environment, lime substances rapidly dissociate or react with water. These reactions, together with the equivalent amount of hydroxyl ions set free when considering 100mg of the lime compound (hypothetic example), are illustrated below: Ca(OH)2 <-> Ca2+ + 2OH- 100 mg Ca(OH)2 or 1.35 mmol sets free 2.70 mmol OH Ca(OH)2 + 2Ca2SiO4 +9CaCO3 + 13H2O <-> 14Ca2+ + 2SiO2 + 9CO2 + 28OH- 100 mg “Reaction mass of limestone and dicalcium silicate” or 0.08 mmol sets free 2.24 mmol OH- has to be noted that CO32- is not expected to directly release two hydroxyl ions under most environmental conditions (depends on CO2 concentrations and pH) and this is therefore a worst case assumption. From these reactions it is clear that the effect of "Reaction mass of limestone and dicalcium silicate" will be caused either by calcium or hydroxyl ions. Since calcium is abundantly present in the environment and since the effect concentrations are within the same order of magnitude of its natural concentration, it can be assumed that the adverse effects are mainly caused by the pH increase caused by the hydroxyl ions. Furthermore, the above mentioned calculations show that the base equivalents are within a factor 2 for lime (chemical), hydraulic and calcium hydroxide. As such, it can be reasonably expected that the effect on pH of "Reaction mass of limestone and dicalcium silicate" is comparable to calcium hydroxide for a same application on a weight basis. Consequently, read-across from calcium hydroxide to "Reaction mass of limestone and dicalcium silicate" is justified.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Calcium dihydroxide
EC Number:
EC Name:
Calcium dihydroxide
Cas Number:
Molecular formula:
calcium dihydroxide
Details on test material:
IUPAC name: Calcium dihydroxide
Product type: PRECAL(R) 50S
Batch no: 7025
Received: 30 January 2007
Purity active ingredient: 98.2% calcium dihydroxide
Chemical analysis: 74.4% CaO, 0.6% MgO, 0.07% SiO2, 0.05% Al2O3, 0.04% Fe2O3, 0.02% Mn3O4, 0.01% SiO3
Air jet sieving: R>90 um 4%; R>200 um 0.1%; R>630 um 0%
Laser particle size distribution: 27.3% <1 um; 50% < 1.7 um; 97% < 50 um
Expiry date: 30 January 2009
Appearance: white powder
Water solubility (20°C): 1.26 g/l
Storage conditions: room temperature, dry conditions

Sampling and analysis

Analytical monitoring:
Details on sampling:
- samples were taken in duplicate of all test solutions and the control
- stored with minimum headspace above solution at ambient temperature in plastic bottles
- sampling time points: at beginning of test and at the end of test immediately after determination of biological and physico-chemical parameters

Test solutions

Details on test solutions:
- Evidence of undissolved material (e.g. precipitate, surface film, etc): With increasing test item concentrations, precipitates formed over time. The formation of precipitates is likely the result of the reaction
between Calcium hydroxide and Carbon dioxide dissolved in the medium yielding poorly soluble Calcium carbonate. At the end of the test, precipitates were found to be difficult to release from the bottom of
the test vessels.
- test item was weighed for each test vessel into a weighboat, added to 10L of temperature adapted test medium directly in the test tank and stirred vigorously for 1 minute. under stirring the pH was

Test organisms

Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
- common name: rainbow trout
- source: Forellenzucht Trostadt GbR, 98646 Trostadt, Thüringen, Germany
- date of purchase: August 13, 2007
- additional information see 'Holding conditions' in table 1

Study design

Test type:
Water media type:
Limit test:
Total exposure duration:
96 h

Test conditions

232 mg/L CaCO3
Test temperature:
Dissolved oxygen:
8.4-10.1 mg/L
Details on test conditions:
− Amount of test solution per test vessel: 10 L
− Depth of test solution in the test vessels: 11.5 cm
− Number of fish per test vessel: 7
− Average length of fish: 4.8 ± 0.6 cm (n = 11)
− Average weight of fish: 1.2 ± 0.5 g (n = 11)
− Fish loading: 0.84 g per L
− Renewal of the test solution during the test period: none
− Feeding: none
− Photoperiod: light/dark - 12 h/12 h
− Light intensity: 100 - 1000 lx; measured: 255 ± 34 (SD) lx
− Temperature (min / max): 15.0 / 15.5 °C
− Aeration: permanent
Reference substance (positive control):

Results and discussion

Effect concentrations
96 h
Dose descriptor:
Effect conc.:
50.6 mg/L
Nominal / measured:
Conc. based on:
not specified
Basis for effect:
mortality (fish)
Details on results:
- Behavioural abnormalities: no data
- Other biological observations: at 33.3 mg/L and higher an increased mucus production was observed. At 50 and 75 mg/L (initial pH 11.1) all fish showed whitish discoloration of the fins, probably due to
severe corrosion.
- Mortality of control: no
- Other adverse effects control: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: the measured Ca concentrations were much below the nominal concentrations, due to the high
concentration of Ca from CaCl2 already present in the test medium, and due to the reaction of the test item with CO2 to poorly soluble CaCO3, thus forming precipitates. However, measurement of Ca after
acidification at the end of the test resulted in a recovery of 98% (58-122%).
- Initial pH values: 7.8 (control), 9.6 (14.8 mg/L), 9.9 (22.2 mg/L), 10.4 (33.3 mg/L), 10.8 (50 mg/L) and 11.1 (75 mg/L).

Applicant's summary and conclusion

Validity criteria fulfilled:
Mortality in the control: 0%. Dissolved oxygen concentration in control and test vessels: ≥84,8%
A clear concentration-response relationship was observed.
The biological findings were closely related to the initial pH of the test solutions. Therefore the initial pH is considered to be the main reason for the effects of the test item on the test organisms.