Silver carbonate

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP status unknown, similar to standard guideline, methods well-described, reliable with restrictions

Principles of method if other than guideline:

10-day sediment test following a protocol adapted from standardised US EPA test procedures.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
None

Analytical monitoring:

yes

Details on sediment and application:

Sediment samples were collected from two lakes.
Bond lake sediment: 95.3% sand; 0.29% TOC
West Bearskin lake sediment: 59.0% silt, 11.2% clay; 2.5% TOC
A solution of AgNO3 was added into a weighted quantity of wet sediment and stirred with a motorised stirrer to yield desired nominal concentrations of AgNO3 on a dry-weight basis.

Test organisms (species):

Hyalella azteca

Details on test organisms:

Age: 7 - 14 days
Source: University of Wisconsin-Superior culture facility

Study type:

laboratory study

Test type:

flow-through

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

10 d

Exposure phase:

total exposure duration

Post exposure observation period:

None

Hardness:

Bond lake test: 48.1 +-2.05 mg/l as CaCO3
West Bearskin lake test: 57.3 +- 2.8 mg/l as CaCO3

Test temperature:

Bond lake test: 22.9 +- 0.2°C
West Bearskin lake test: 22.9 +- 0.2°C

pH:

Bond lake test: 7.75 +- 0.14
West Bearskin lake test: 7.66 +- 0.32

Dissolved oxygen:

Bond lake test: 7.8 +- 0.48 mg/l
West Bearskin lake test: 7.9 +- 0.3 mg/l

Salinity:

No data

Ammonia:

Bond lake test: 0.15 +- 0.1 mg/l
West Bearskin lake test: 0.076 +-0.057 mg/l

Nominal and measured concentrations:

Bond lake: Nominal Ag concentrtions: 0.012, 0.031, 0.078, 0.195, 0.487 and 1.22 g Ag/kg dry sediment
West Bearskin lake: 1.08, 2.15, 4.31,8.61, 17.2 and 34.4 g Ag/kg dry sediment.
Spiked sedmiment samples were flushed with overlying water for 7 days prior to addition of the test animals.

Details on test conditions:

Number of replicates: 3
Number of animals per replicate: 10
4 additional replicate beakers at each exposure level reserved for chemical analysis.
The 7 beakers for each exposure level and control were kept in an aquarium that was replenished with freshwater to provide a minimum of 4 volume exchanges per day.
Aquaria were placed in a temperature controlled water bath, 23 +- 2°C

Reference substance (positive control):

no

Duration:

10 d

Dose descriptor:

LC50

Effect conc.:

0.084 other: g/kg

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality

Remarks on result:

other: Bond lake sediment

Duration:

10 d

Dose descriptor:

LC50

Effect conc.:

2.98 other: g/kg

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality

Remarks on result:

other: West Bearskin lake sediment

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

0.012 other: g/kg

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: Bond lake sediment

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

2.15 other: g/kg

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: West Bearskin lake sediment.

Conclusions:

The 10-day LC50 values were 0.084 g Ag/kg and 2.98 g Ag/kg for the two sediment types. The 10-day NOECs were 0.012 g Ag/kg and 2.15 g Ag/kg for the two sediment types, based on growth.

Executive summary:

The GLP status of this study is not known. It follows an adapted version of a standard guideline. The methods are well-described and it is considered reliable and suitable for use for this endpoint. The most sendistive

Description of key information

The most sensitive endpoint is a 10-day NOEC (growth) for Hyalella azteca of 12 mg Ag/kg dry weight (Call et al. 2006). 

Additional information

Long-term NOECs are available for three benthic species:Chironomus tentans (Call et al. 1999), Hyalella azteca (Hirsch 1998a, Call et al. 2006) and Lumbriculus variegatus (Hirsch 1998b). The most sensitive reported sediment NOEC is 12 mg Ag/kg dry sediment for growth of the amphipod Hyalella azteca exposed after a 10 day exposure to contaminated sediments (Call et al. 2006). The organic carbon content of the sediment used to generate this NOEC was 0.29%.

The derivation of the PNECsediment, including the basis for a correction for sediment organic carbon concentration is described in the appended PNEC summary document.

Berry et al. (1999) exposed the marine amphipod Ampelisca abdita for 10 days to two marine sediments with different amounts of acid-volatile sulfide spiked with silver (Sediment 1: 2.7 – 4415 mg silver/kg dw, Sediment 2: 2.7 – 72,770 mg silver/kg dw). The EC10 values for these two sediments were 4415 and 6626 mg/kg, respectively. In general, sediment treatments with an excess of acid-volatile sulfide (AVS) relative to simultaneously extracted metal were not toxic to marine amphipods.