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Short-term toxicity to aquatic invertebrates

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short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Non-GLP, non-guideline study, published in peer reviewed literature, some limitations in design and/or reporting but otherwise adequate for assessment.
Principles of method if other than guideline:
The protective effect of reactive sulphide against AgNO3 toxicity to Daphnia magna neonates was studied. Acute (48 hour) toxicity tests were performed in the absence (<5 nM) and presence of low (~25 nM) and high (~250 nM) concentrations of zinc sulphide clusters under oxic conditions.
GLP compliance:
not specified
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable
Analytical monitoring:
Details on sampling:
Full details provided in partner publication. Bowles et al. ET&C Vol. 21
Details on test solutions:
To ensure standardised conditions for water chemistry, synthetic water used for all tests was prepared as a single batch employing 1000 L of reverse osmosis-purified water in a food-grade polyethylene tank. Water was designed to resemble Lake Ontario (Canada) water and was slightly lower in hardness (115 vs. 150 mg/L CaCO3) and higher in pH (8.2 vs. 7.5) than the culture water used by the supplier. The synthetic water was bubbled with pure CO2 for 24 hours to ensure that CaCO3 went into solution and then was bubbled with air for 48 hours to ensure removal of excess CO2 and atmospheric equilibration. Water was then left to stand for 2 weeks prior to use.
Test organisms (species):
Daphnia magna
Details on test organisms:
Source aquatic Research Organisms, Hampton, NH, USA (ARO strain, lot 090600 brood origination US EPA, Cincinnati, OH, USA). Acclimated to synthetic water used in tests; fed a slurry of yeast, cerophyll, and trout chow. Following acclimation, reproduction rate was measured to ensure it met established criteria for a healthy population. Neonates passed through the mesh and into the aquarium of synthetic water and were collected within 6 to 24h of hatch for toxicological studies.
Test type:
Water media type:
Limit test:
Total exposure duration:
48 h
Remarks on exposure duration:
Also 24 hours
Post exposure observation period:
115 mg/L CaCO3
Test temperature:
Dissolved oxygen:
PO2 = 164.2 ± 1.9 mmHg; n = 10
Not applicable
Nominal and measured concentrations:
In the absence of sulfide, nominal concentrations were 0 (control), 0.05, 0.1, 0.2, 0.5, 1, and 2 µg Ag/L (0, 0.46, 0.93, 1.9, 4.6, 9.3, and 19 nM) in both toxicity tests.
Details on test conditions:
Synthetic water in borosilicate glass beakers, acid washed in 1% HNO3 and rinsed with synthetic water prior to use. Three replicas of ten organisms per vessel were used with no aeration. Solution renewed after 24 hours. A 16 hour light, 8 hour dark day was used. The organisms were not fed.
Reference substance (positive control):
48 h
Dose descriptor:
Effect conc.:
0.22 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
Basis for effect:
Remarks on result:
other: 95% CL 0.19–0.25 µg Ag/L. Filtered (0.45 mm), silver concentration.
Details on results:
Results also for 24 hour LC50 and with added sulphide. Reactive sulfide protects D. magna against acute silver toxicity.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
The 48 hour LC50 values and the respective 95% confidence intervals were estimated on the basis of the cumulative mortality data using probit analysis. These values were estimated on the basis of both nominal and mean measured total and filtered silver concentrations over the respective periods of the test and the results were compared.
Validity criteria fulfilled:
not applicable
The freshwater 48 hour LC50 values for Daphnia magna when exposed to silver nitrate are 0.18 to 0.26 µg Ag/L based on measured total silver concentration and 0.22 µg Ag/L based on measured filtered silver concentration.
Executive summary:

The study is a non-guideline study, published in peer reviewed literature and considered suitable for use as a key study for this endpoint. The freshwater 48 hour LC50 values for Daphnia magna when exposed to silver nitrate are 0.18 to 0.26 µg Ag/L based on measured total silver concentration and 0.22 µg Ag/L based on measured filtered silver concentration.

Description of key information

The lowest reported 48 hour EC50 is 0.22 µg Ag/L for Daphnia magna based on measured dissolved silver (Bianchini et al. 2002). This value is also selected as the acute ERV for classification purposes.

Key value for chemical safety assessment

Additional information

Data were available from several published sources on the short-term toxicity of silver to freshwater invertebrates when silver nitrate was used as the test substance. The most sensitive 48 hour EC50 is reported by Bianchini et al. (2002) for the water flea, Daphnia magna. Similar EC50 values were reported by other authors (e.g. Glover et al. 2005).

In freshwater, short-term tests indicate that invertebrates are more sensitive than fish. Within the invertebrates, cladocerans and amphipods are more sensitive than aquatic insects, which are in turn more sensitive than other tested invertebrate groups. This is consistent with other metals (e.g. copper and cadmium).

Data on the toxicity of silver to marine invertebrates are more limited. However, the data indicate that marine invertebrates are less sensitive to silver than freshwater species. The most sensitive acute LC50 (mortality) for a marine invertebrate is 15 μg Ag/L for the sea urchin Strongylocentrotus purpuratus (Dinnel et al. 1989).