Silver

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to fish, other

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Substance considered to fall within the scope of the read-across 'Silver metal: Justification of a read-across approach for environmental information requirements' (document attached in IUCLID section 13).

Reason / purpose for cross-reference:

read-across source

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

130 other: μg dissolved Ag/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element

Remarks:

silver

Basis for effect:

other: mortality and growth

Remarks on result:

other: at 30% salinity

Details on results:

The effect values from the toxicity test demonstrate that increasing salinity has a mitigating effect on silver toxicity if toxicity is determined using measured concentrations of dissolved silver.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Values for NOEC and LOEC were calculated using ANOVA and a parmetric Dunnettt's test or nonparametric William's test. The LC20 calculated by weighted least-squares nonlinear regression, and the EC50 calculated by binomial/nonlinear interpolation. (p<0.05).

Salinity	NOEC	LOEC	EC20	ACR
‰	µg/L dissolved Ag
Mysids
10	6	13	3.9	>3.2
20	34	60	60	5.8
30	19	37	35	9.3
Fish
10	26	42	38	3
20	49	100	100	1.9
30	130	290	170	> 3

Validity criteria fulfilled:

not specified

Conclusions:

The 28 day NOEC (mortality and growth) is 130 μg dissolved Ag/L.

Executive summary:

This is a GLP, guideline study and is considered reliable and fully acceptable for use for this endpoint.

Reference 2

Endpoint:

fish early-life stage toxicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Substance considered to fall within the scope of the read-across 'Silver metal: Justification of a read-across approach for environmental information requirements' (document attached in IUCLID section 13).

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

217 d

Dose descriptor:

EC10

Effect conc.:

0.23 µg/L

95% CI:

>= 0.19 - <= 0.27

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

silver

Basis for effect:

mortality

Remarks on result:

other: water hardness: soft

Duration:

217 d

Dose descriptor:

EC10

Effect conc.:

0.8 µg/L

95% CI:

>= 0.75 - <= 0.85

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

silver

Basis for effect:

mortality

Remarks on result:

other: water hardness: medium

Duration:

217 d

Dose descriptor:

EC10

Effect conc.:

1.39 µg/L

95% CI:

>= 1.22 - <= 1.58

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

silver

Basis for effect:

mortality

Remarks on result:

other: water hardness: hard

Details on results:

Chronic values were defined on the basis of mortality, though very similar toxic limits were also defined based on retarded embryonic development and growth of early life stages. Despite early retardation of development and growth, after more than six months of exposure, fish did not show significant differences in growth between silver exposure concentrations and controls at termination of the experiments.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Effect concentrations were evaluated based on mortality with chronic values calculated from their geometric mean.

Validity criteria fulfilled:

yes

Remarks:

Validity criteria in OECD 201 met

Conclusions:

217 day early-life stage EC10 (mortality) of AgNO3 to Salmo trutta was determined to be 0.23 µg/L dissolved Ag.

Executive summary:

In a non-GLP, guideline test, the 217 day early-life stage EC10 (mortality) of AgNO3 to Salmo trutta was determined to be 0.23 µg/L dissolved Ag.

Reference 3

Endpoint:

fish early-life stage toxicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Substance considered to fall within the scope of the read-across 'Silver metal: Justification of a read-across approach for environmental information requirements' (document attached in IUCLID section 13).

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

196 d

Dose descriptor:

EC10

Effect conc.:

0.17 µg/L

95% CI:

>= 0.17 - <= 0.18

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

silver

Basis for effect:

mortality

Remarks on result:

other: soft

Duration:

196 d

Dose descriptor:

EC10

Effect conc.:

0.44 µg/L

95% CI:

>= 0.38 - <= 0.52

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

silver

Basis for effect:

mortality

Remarks on result:

other: medium

Duration:

196 d

Dose descriptor:

EC10

Effect conc.:

0.96 µg/L

95% CI:

>= 0.76 - <= 1.2

Nominal / measured:

meas. (geom. mean)

Conc. based on:

dissolved

Remarks:

silver

Basis for effect:

mortality

Remarks on result:

other: hard

Details on results:

Chronic values were defined on the basis of mortality, though very similar toxic limits were also defined based on retarded embryonic development and growth of early life stages. Despite early retardation of development and growth, after more than six months of exposure, fish did not show significant differences in growth between silver exposure concentrations and controls at termination of the experiments.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Effect concentrations were evaluated based on moratlity with chronic values calculated from their geometric mean.

Validity criteria fulfilled:

yes

Remarks:

Validity criteria in OECD 201 met

Conclusions:

The 196 day early-life stage EC10 (mortality) of AgNO3 to Oncorhynchus mykiss was determined to be 0.17 µg dissolved Ag/L.

Executive summary:

In a non-GLP, guideline test, the 196 day early-life stage EC10 (mortality) of AgNO3 to Oncorhynchus mykiss was determined to be 0.17 µg dissolved Ag/L.

Reference 4

Endpoint:

fish early-life stage toxicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Substance considered to fall within the scope of the read-across 'Silver metal: Justification of a read-across approach for environmental information requirements' (document attached in IUCLID section 13).

Reason / purpose for cross-reference:

read-across source

Duration:

73 d

Dose descriptor:

NOEC

Effect conc.:

> 1.25 µg/L

Nominal / measured:

meas. (TWA)

Basis for effect:

other: Mortality; weight; hatching

Remarks on result:

other: dissolved Ag/L, for survival, mean day to hatch, mean day to swimup, growth and whole-body sodium content in the unamended water.

Duration:

77 d

Dose descriptor:

EC10

Effect conc.:

0.89 µg/L

95% CI:

>= 0.47 - <= 1.69

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: EC10 value recalculated from originally reported data

Duration:

77 d

Dose descriptor:

LC10

Effect conc.:

1.24 µg/L

95% CI:

>= 1.11 - <= 1.37

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: LC10 value recalculated from originally reported data

Duration:

77 d

Dose descriptor:

NOEC

Effect conc.:

> 2.26 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

time to hatch

Details on results:

Survival NOEC >1.25 µg l-1 soft; 1.09 µg l-1 amended (4.4 ± 5 % survival at 2.26 µg l-1). No sublethal effect seen in soft water exposure. Growth (mean dry weight) NOEC 0.21 µg l-1; LOEC 0.48 µg l-1

Reported statistics and error estimates:

NOEC and LOEC values determined using Anova followed by Dunnett’s test, Wilcoxon’s rank sum test or Steel’s many-one rank test. LC10 and EC10 have been re-calculated using log-logistic curve fitting (TRAP software)

See table provided in Materials and methods.

The chronic toxicity of silver to rainbow trout, Oncorhynchus mykiss, was determined in flow-through exposures in two water types; soft water in the presence and absence of 49 mg l-1 NaCl (30 mg Cl l-1). Rainbow trout embryos were exposed to silver (as AgNO3) from 48h or less post-fertilization to 30d post-swimup. The NOEC was > than 1.25 μg dissolved Ag l-1 (measured) for survival, mean day to hatch, mean day to swimup, growth and whole-body sodium content in the unamended water. 96% mortality was observed in the highest test concentration in the NaCl-amended water exposure 4 μg Ag l-1, nominal (2.26 μg dissolved Ag l-1 measured). This concentration was not included in the unamended water exposures. Average dry weights of surviving organisms exposed in NaCl-amended water were significantly reduced in treatments ≥ 0.48 μg dissolved Ag l-1, the NOEC was 0.21 μg dissolved Ag l-1. Differences in sensitivity to silver may have been partly due to the fact that different strains of rainbow trout were used. Whole body silver concentrations increased significantly at 0.13 μg dissolved Ag l-1 (measured) in unamended water and at 1.09 dissolved Ag l-1 (measured) in NaCl-amended water.

Validity criteria fulfilled:

yes

Conclusions:

The 73-day NOEC was >1.25 μg dissolved Ag/L for survival, mean day to hatch, mean day to swimup, growth and whole-body sodium content in the unamended water.
Reliable LC10 and EC10 for O. mykiss for the endpoint mortality of 1.24 μg/L and 0.89 μg/L for the endpoint weight could be extracted. All values are reported as dissolved Ag.

Executive summary:

This guideline study observed GLP and is considered reliable and fully acceptable for use as a supporting study for this endpoint. Reliable LC10 and EC10 for O. mykiss for the endpoint mortality of 1.24 μg/L and 0.89 μg/L for the endpoint weight could be extracted. All values are reported as dissolved Ag.

Reference 5

Endpoint:

fish early-life stage toxicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Substance considered to fall within the scope of the read-across 'Silver metal: Justification of a read-across approach for environmental information requirements' (document attached in IUCLID section 13).

Reason / purpose for cross-reference:

read-across source

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

0.351 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: mortality and growth rate

Remarks on result:

other: HT conditions

Duration:

32 d

Dose descriptor:

EC10

Effect conc.:

0.66 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: HT conditions; EC10 value recalculated from originally reported data

Duration:

32 d

Dose descriptor:

EC10

Effect conc.:

0.65 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: HT conditions; EC10 value recalculated from originally reported data

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

> 0.795 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

number hatched

Remarks on result:

other: HT conditions

Duration:

33 d

Dose descriptor:

NOEC

Effect conc.:

0.27 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: mortality; growth rate; number hatched

Remarks on result:

other: HT-high conditions. Estimated Ag concentrations 81% of nominal Ag as total Ag, 53% as dissolved Ag.

Duration:

33 d

Dose descriptor:

EC10

Effect conc.:

0.42 µg/L

95% CI:

>= 0 - <= 1 542

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: HT-high conditions. Estimated Ag concentrations 81% of nominal Ag as total Ag, 53% as dissolved Ag. EC10 value recalculated from originally reported data.

Duration:

33 d

Dose descriptor:

EC10

Effect conc.:

0.32 µg/L

95% CI:

>= 0.23 - <= 0.45

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: HT-high conditions. Estimated Ag concentrations 81% of nominal Ag as total Ag, 53% as dissolved Ag. EC10 value recalculated from originally reported data.

Key result

Duration:

33 d

Dose descriptor:

EC10

Effect conc.:

0.38 µg/L

95% CI:

>= 0.25 - <= 0.59

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

number hatched

Remarks on result:

other: HT-high conditions. Estimated Ag concentrations 81% of nominal Ag as total Ag, 53% as dissolved Ag. EC10 value recalculated from originally reported data.

Duration:

34 d

Dose descriptor:

NOEC

Effect conc.:

1 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: HT-high NaCl conditions. Estimated Ag concentrations 90% of nominal Ag as total Ag, 67% as dissolved Ag.

Duration:

34 d

Dose descriptor:

EC10

Effect conc.:

0.25 µg/L

95% CI:

>= 0 - <= 70 000 000

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: HT-high NaCl conditions. Estimated Ag concentrations 81% of nominal Ag as total Ag, 53% as dissolved Ag. EC10 value recalculated from originally reported data.

Duration:

34 d

Dose descriptor:

NOEC

Effect conc.:

0.5 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: HT-high NaCl conditions. Estimated Ag concentrations 90% of nominal Ag as total Ag, 67% as dissolved Ag.

Duration:

34 d

Dose descriptor:

EC10

Effect conc.:

0.86 µg/L

95% CI:

>= 0.56 - <= 1.33

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: HT-high NaCl conditions. Estimated Ag concentrations 81% of nominal Ag as total Ag, 53% as dissolved Ag. EC10 value recalculated from originally reported data.

Duration:

34 d

Dose descriptor:

NOEC

Effect conc.:

> 2 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

number hatched

Remarks on result:

other: HT-high NaCl conditions. Estimated Ag concentrations 90% of nominal Ag as total Ag, 67% as dissolved Ag.

Details on results:

Dissolved Ag calculated based on mean recovery between unfiltered and filtered samples.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

NOEC and LOEC values determined using Anova followed by Dunnett’s test, or Steel’s many-one rank test. EC10 have been re-calculated using log-logistic curve fitting (TRAP software).

Validity criteria fulfilled:

yes

Conclusions:

Wide confidence intervals of the LC10 values are noted for the endpoint mortality and therefore only the NOEC were selected for that endpoint, i.e. NOEC of 0.351, 0.27 and 1.0 μg/L, resulting in a geomean of 0.46 µg/L.
For the endpoint hatching the EC10 of 0.38 μg/L was selected.
For the endpoint growth the NOEC of 0.351, and the EC10 of 0.32 and 0.86 μg/L were selected, resulting in a geomean of 0.46 µg/L.

Executive summary:

A GLP, guideline, 34 days post-hatch early-life stage test with AgNO3 to Pimephales promelas ws performed.

Wide confidence intervals of the LC10 values are noted for the endpoint mortality and therefore only the NOEC were selected for that endpoint, i.e. NOEC of 0.351, 0.27 and 1.0 μg/L, resulting in a geomean of 0.46 µg/L.

For the endpoint hatching the EC10 of 0.38 μg/L was selected.

For the endpoint growth the NOEC of 0.351, and the EC10 of 0.32 and 0.86 μg/L were selected, resulting in a geomean of 0.46 µg/L.

All toxicity values are expressed as dissolved Ag.

Description of key information

Read across from ionic silver

Plus supporting published data from several studies included in the REACH dossier as Endpoint Study Records with various sizes of nanoparticles and coating types, showing that nanosilver is less toxic than ionic silver

Additional information

Summary of available data for uncoated and coated nanosilver

Reliable and relevant data in the long-term toxicity of uncoated and coated nanosilver to fish are available from two studies (Kwok et al. 2012, Schäfers and Weil 2013). Both studies were based on early-life stage exposure of fish embryos. Kwok et al. (2012) report the effects of various forms of nanosilver on Oryzias latipes (Japanese medaka) after 21 days exposure, whilst Schäfers and Weil (2013) report the effects of exposure to NM-300K standard nanosilver in Danio rerio (zebra fish) after a 35 day OECD 210 early life test. Both studies were conducted in freshwater media.

Kwok et al. (2012) exposed medaka embryos to two sizes of PVP coated spherical nanoparticles with mean raw materials particle sizes of 21 ± 7 and 75 ± 21 nm, as well as citrate and gum arabic coated nanosilver particles with mean particle raw materials sizes of 7 ± 11 and 6 ± 2 nm, respectively (gum arabic particle measurements are based on the silver core of the particles). All forms of nanosilver were found to aggregate/agglomerate in test systems, with aggregates/agglomerates of PVP coated silver nanoparticles reported to exceed 1 µm in size after 48 hours within the test system. NOECs for survival after 21 days exposure ranged from 150 µg/L for the larger PVP coated and citrate coated nanosilver particles, 500 µg/L for the gum arabic coated silver particles and 1,500 µg/L for the smallest PVP coated nanoparticles. The equivalent NOEC for ionic silver (silver nitrate) exposure for 21 days was 15 µg/L, approximately 10 times more toxic than the forms of nanosilver used in the study.

Schäfers and Weil (2013) exposed zebrafish embryos to uncoated NM-300K nanosilver in an OECD standard early life-stage toxicity test (OECD 210). NM-300K has a primary particle size of 15 nm (with 99% of particles below 20 nm) and is widely used in the OECD Sponsorship Programme for the testing of engineered nanomaterials. Test were semi-static with seven day renewal periods for media. Aggregates of 50-60 nm were reported in test media and were considered stable between media renewals. The test was initiated with fertilised eggs and various endpoints were monitored during the test period including hatching success, post-hatch success (survival), length, weight and abnormal development. All test validity criteria were achieved and an overall NOEC of 5.9 µg/L was reported (length and weight endpoints). An EC10 of 41 µg/L was also reported for post-hatch survival. No concurrent exposure with ionic silver was undertaken.

Neither of the studies report effects at concentrations approaching the EC10 for chronic exposure to fish of 0.17 µg/L for ionic silver used in the REACH CSR. The EC10 for ionic silver is currently approximately 30 times more sensitive than the most sensitive chronic fish toxicity data for nanosilver, although the exposure duration of the study with dissolved silver was significantly longer than the available studies with nanosilver. As such, the hazard properties of ionic silver are considered to adequately cover the potential hazard of nanosilver to fish.

There is currently insufficient information available to make any conclusions regarding the influence of particle size, morphology or coating on the long-term toxicity of nanosilver to fish.