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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:
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: see 'Remark'
Remarks:
Acceptable, well-documented publication, which meets basic scientific principles. No reproduction assessed. 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- CaO + H2O <-> Ca2+ + 2OH- 100 mg CaO or 1.78 mmol sets free 3.56 mmol OH- From these reactions it is clear that the effect of calcium oxide 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 calcium oxide and calcium hydroxide. As such, it can be reasonably expected that the effect on pH of calcium oxide is comparable to calcium hydroxide for a same application on a weight basis. Consequently, read-across from calcium hydroxide to calcium oxide is justified.
Reason / purpose for cross-reference:
reference to same study
Principles of method if other than guideline:
Toxicity test was conducted by a standard method developed by the laboratory. Test organisms were exposed, 14 d, to different concentrations of the test item in test solutions, prepared in natural seawater.
GLP compliance:
not specified
Analytical monitoring:
no
Details on sampling:
Temperature was checked daily. Water quality was measured three timed a week.
Vehicle:
no
Details on test solutions:
Test solutions were prepared for the samples in natural seawater, acclimated to 15+/-1°C, and initial water quality was measured.
Test organisms (species):
Crangon septemspinosa
Details on test organisms:
- common name: sand shrimp
- source: collected from Kouchibouguac Bay, NB, Canada
- wet weight: mean 3.00 +/- 1.307 mg (n = 20)
Test type:
semi-static
Water media type:
saltwater
Limit test:
no
Total exposure duration:
14 d
Post exposure observation period:
not applicable
Hardness:
no data
Test temperature:
no data
pH:
7.95-9.78
Dissolved oxygen:
no data
Salinity:
no data
Nominal and measured concentrations:
nominal concentrations: 0, 3.2, 10, 32, 100, 320 mg/L
Details on test conditions:
- 20 replicates per test concentration
- water renewal: 80 % of test solution replaced 3 times a week with fresh solution
- feeding frequency: 3 times a week
- feed: 100 mg frozen brine shrimp with some live brine shrimp for the first week, and 200 mg frozen brine shrimp in week two
- after 14 days each sand shrimp was weighed (dry weight).
Reference substance (positive control):
not specified
Duration:
14 d
Dose descriptor:
LC50
Effect conc.:
53.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CL: 48.3-58.4 mg/L
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
- at concentrations of 100 and 320 mg/L a 100 % mortality was observed
- at other concentrations mortality ranged between 5 and 15 %
- no effects on growth were observed.
Results with reference substance (positive control):
not applicable
Reported statistics and error estimates:
- LC50s were calculated following Stephan (1977)
- Analysis of variance was used to examine the effect of treatments on sand shrimp weights (log-transformed to normalize) (JMP version 4, SAS Institute 2000)
Validity criteria fulfilled:
not specified
Conclusions:
In the current test with sand shrimp, the 14d-LC50 for hydrated lime was 53.1 mg/L. Based on pH values measured at t=0 this is equivalent to 9.20 (9.12-9.28) pH units. No effects on growth were observed.

Description of key information

Klimisch 2 study (Locke et al., 2009): nominal 14d-NOEC value for mortality of Crangon septemspinosa = 32 mg Ca(OH)2/L
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-
CaO + H2O <-> Ca2+ + 2OH-
100 mg CaO or 1.78 mmol sets free 3.56 mmol OH-
From these reactions it is clear that the effect of calcium oxide 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 calcium oxide and calcium hydroxide. As such, it can be reasonably expected that the effect on pH of calcium oxide is comparable to calcium hydroxide for a same application on a weight basis. Consequently, read-across from calcium hydroxide to calcium oxide is justified.
An acute toxicity study to Daphnia magna was performed according to OECD 202 with a saturated solution (100% v/v) of calcium carbonate (nano) (Priestly, 2010). No immobilisation or toxic effects were observed in any of the Daphnia magna exposed. As a result, calcium carbonate is considered not acutely toxic to aquatic invertebrates and hence long term testing is considered to be unnecessary.

Key value for chemical safety assessment

Marine water invertebrates

Marine water invertebrates
Effect concentration:
32 mg/L

Additional information