Silver

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

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:

48 h

Dose descriptor:

EC10

Effect conc.:

0.31 µg/L

95% CI:

>= 0.13 - <= 0.73

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: population size

Remarks on result:

other: Effect concentrations are expressed as the geometric mean of the measured dissolved Ag concentrations in fresh and old solutions.

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

2.6 µg/L

95% CI:

>= 1.5 - <= 4.7

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: population growth rate

Remarks on result:

other: Effect concentrations are expressed as the geometric mean of the measured dissolved Ag concentrations in fresh and old solutions.

Details on results:

Concentration–response analysis was based on the time-weighted average of dissolved Ag concentrations measured in fresh medium after algae addition (t 0 h) and those measured in the old solutions after the 24 (when available) and 48-h exposures. These time-weighted average dissolved Ag concentrations were on average 90 ± 4% lower than nominal concentrations.

Reported statistics and error estimates:

Effect concentrations were calculated based on relative responses (expressed relative to the mean control response of the respective experiment). The EC10, EC20, and EC50 values and corresponding confidence intervals were determined based on a log-logistic concentration response model with 2 parameters using Statistica software.
NOEC and LOECs were calculated with the nonparametric Jonckheere-Terpstra test.

Overview of average* population size (at end of test) and population growth rate in the different exposure treatments of the 48-h Brachionus calyciflorus reproduction test

	Dissolved Ag (µg/L)
Nominal Ag concentration (µg/L)	t 0 h before algae addition	t 0 h after algae addition	t 24 h	t 48 h	Time-weighted dissolved Ag**(µg/L)	Population size	Population growth rate (d^–1)	Mortality (%)
Control	<0.01	<0.01	<0.01	<0.01	<0.01	7.4 ± 0.7	0.95 ± 0.07	6
5	2.8	0.7	<3.7	0.07	0.27	6.9 ± 0.4	0.95 ± 0.03	0
10	6.6	1.4	<3.7	0.12	0.52	6.1 ± 0.4	0.89 ± 0.04	0
20	20	4.5	<3.7	0.23	1.4	5.3 ± 0.4	0.82 ± 0.03	0
40	38	9.8	5.0	2.1	5.2	4.3 ± 0.4	0.70 ± 0.04	0
80	89	18	11	4.5	11	3.6 ± 0.2	0.62 ± 0.04	0
160	172	30	21	18	23	4.0 ± 0.4	0.65 ± 0.06	0
320	296	42	33	34	35	0.3 ± 0.2	0.02 ± 0.02	75

*Average of all replicates ± standard error is reported.

**Time-weighted average of dissolved Ag concentrations in fresh solutions at t 0 h (after addition of algae) and in old solutions at t 24 h (when available) and t 48  h.

Above table shows that a clear concentration–response behavior of population size and population growth rate was observed.

Corresponding effect concentrations are shown in the table below. The EC10 and EC50 values for population size are lower than for population growth rate, and NOEC and LOEC levels for both endpoints are similar.

Effect concentrations(expressed as the geometric mean of the measured dissolved Ag concentrations in fresh and old solutions )for the 48h-Brachionus calyciflorustest.

 

Endpoint	EC10 (μg diss. Ag/L)	EC20 (μg diss. Ag/L)	EC50 (μg diss. Ag/L)	NOEC (μg diss. Ag/L)	LOEC (μg diss. Ag/L)
Population size	0.31 (0.13-0.73)	1.0 (0.6-1.9)	8.2 (5.9-11.3)	0.27 6.8±7.8	0.52 17.0±8.6
Population growth rate	2.6 (1.5-4.7)	5.2 (3.5-7.7)	16.7 (13.5-20.7)	0.27 0.2±4.6	0.52 6.9±5.3

EC10, EC20 and EC50’s were calculated using a log-logistic concentration response model with 2 parameters. 95% confidential intervals are reported between parentheses.

NOEC and LOECs were calculated using the non-parametric Jonkhere-Terpstra-test. The average growth rate inhibition±standard error relative to the control (%) at the NOEC or LOEC are reported between brackets.

Validity criteria fulfilled:

yes

Remarks:

The average control population size at the end of the test was 7.4 ± 0.7 rotifers. Reproduction occurred in 94% of the control replicates, and the control population growth rate was 0.95 ± 0.07 d–1. As such, the test is considered valid.

Conclusions:

An EC10 of 0.31 μg dissolved Ag /L for the endpoint population size and an EC10 of 2.6 μg dissolved Ag /L for the endpoint population growth rate was found after 48h exposure of B. calyciflorus to silver nitrate.

Executive summary:

In a 48 hour study with the rotifer Brachionus calyciflorus exposed to silver nitrate, the EC10 for the most sensitive endpoint (population size) was 0.31 µg dissolved Ag/L.

This is a guideline study considered suitable for use as a key study for this endpoint.

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

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:

21 d

Dose descriptor:

EC10

Effect conc.:

2.7 µg/L

95% CI:

>= 2.2 - <= 3.4

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

2.9 µg/L

95% CI:

>= 2.8 - <= 3

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Details on results:

The EC10 for Daphnia magna is 2.14 µg/L for growth.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

EC10 values have been re-calculated using Graph Digitizer and log-logistic curve fitting (TRAP software). Dose response curves are reported.

Validity criteria fulfilled:

yes

Conclusions:

For D. magna EC10 value of 2.7 μg/L is calculated for the endpoint growth. For the endpoint reproduction, EC10 of 2.9 μg/L is calculated. All toxicity valus are expressed as dissolved Ag.

Executive summary:

This is a non-GLP, chronic toxicity study on Daphnia magna following ASTM guidelines for conducting D. magna life cycle tests. EC10 values of 2.7 μg/L for the endpoint growth and 2.9 μg/L for the endpoint reproduction are calculated. All toxicity valus are expressed as dissolved Ag.

The study is considered reliable and suitable for use for this endpoint.

Reference 3

Endpoint:

long-term toxicity to aquatic invertebrates

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:

10 d

Dose descriptor:

EC10

Effect conc.:

12.54 µg/L

95% CI:

>= 10.4 - <= 15.1

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

13 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth

Details on results:

No data reported

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

NOEC and LOEC values determined using Anova followed by Bonferroni’s test. EC10 have been re-calculated using log-logistic curve fitting (TRAP software)

Validity criteria fulfilled:

not applicable

Remarks:

No applicable criteria but water quality appears acceptable.

Conclusions:

The 10 day EC10 (growth) of AgNO3 to Chironomus tentans was determined to be 12.54 µg dissolved Ag/L.

Executive summary:

In a non-GLP, non-guideline, test the 10 day EC10 (growth) of AgNO3 to Chironomus tentans was determined to be 12.54 µg dissolved Ag/L.

Reference 4

Endpoint:

long-term toxicity to aquatic invertebrates

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:

14 d

Dose descriptor:

EC10

Effect conc.:

1.48 µg/L

95% CI:

>= 1.2 - <= 1.78

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth

Remarks:

growth rate (wet weight)

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

2.56 µg/L

95% CI:

>= 2.3 - <= 2.82

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth

Remarks:

growth rate (wet weight)

Details on results:

The EC10 for Ag of 13.7 nM (=1.48 µg/L) is reported in Table 1 of the study and was derived by compiling all of the different single-metal toxicity tests performed in this study (see also caption under Figure 1 of the study). Since conditions between the different single-metal toxicity tests were identical, it is justified to compile the results to derive a single EC10.
Dose response: dose response curves for growth rate (weight) based on free ion and dissolved Ag are reported
Toxicity value: the manuscript reports an EC10 of 1.48 (1.20-1.78), and EC20 of 1.81 (1.56-2.05) and an EC50 of 2.56 (2.3-2.82) μg/L as dissolved Ag for the endpoint relative growth rate (wet weight).

Reported statistics and error estimates:

EC10 values were calculated based on the reported dose-response graphs using a log-logistic function. Because the toxicity data analysis was regression-based, treatments had only one replicate to maximize their numbers (32 different Ag concentrations). This allows better coverage of the response curves and surfaces and, hence, increased reliability and power in the analysis.

Validity criteria fulfilled:

not applicable

Remarks:

Validity criteria based on control performance do not exist as this is not a standard test but initial and final growth (weight) is reported in the controls

Conclusions:

Reliable EC10 of 1.48 μg/L (growth rate) could be extracted for L. stagnalis as dissolved Ag.

Executive summary:

Reliable EC10 of 1.48 μg/L (growth rate) could be extracted for L. stagnalis as dissolved Ag.

Reference 5

Endpoint:

long-term toxicity to aquatic invertebrates

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:

14 d

Dose descriptor:

NOEC

Effect conc.:

1 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: molting

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Duration:

14 d

Dose descriptor:

EC10

Effect conc.:

4.1 µg/L

95% CI:

>= 2.5 - <= 6.9

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Details on results:

Survival NOEC of 3.7 µg/L and survival LC10 of 4.1 µg/L (dissolved Ag).
Molting NOEC of 1 µg/L and molting EC10 of 0.31 µg/L (CI: 0.003-37.1) (dissolved Ag); EC10 for molting not selected because of the too wide confidence interval.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Larval survival was analysed at 7 and 14 days to yield NOECs using ANOVA and Dunnett’s Test. Survival data were transformed (arc-sine square root) before analysing by using a significance level of 0.05. Growth was analysed by examining 3 endpoints: A) molt or exuviae production at 7 and 14 days, B) body length after 14 days of exposure and C) head capsule width after 14 days exposure. Differences in the number of molts between treatments and controls were analysed by ANOVA and Dunnett’s test at a p value of 0.05. Treatments were compared to each other with either ANOVA and Tukey’s HSD test (if data satisfied parametric test assumptions) or Kruskal-Wallis nonparametric ANOVA and multiple means test. Differences in final body length and head capsule width between controls and treatments at 14 days were analysed with ANOVA and Bonferroni’s t test (p at 0.05) because these data met parametric test assumptions.
EC10 values were calculated based on the reported dose-response data using a logistic func-tion (TRAP software).

Validity criteria fulfilled:

not applicable

Remarks:

80% survival after 14 d in the control

Conclusions:

Reliable LC10/NOEC could be extracted, i.e. the LC10 of 4.1 μg/L for the endpoint mortality and the NOEC of 1.0 μg/L for the endpoint molting, as dissolved Ag.

Executive summary:

The study presents the results of a subacute toxicity test with the mayfly (Stenonema modestum). A series of effluent toxicity tests were conducted, each consisting of a 14 day exposure using a static-renewal test mode.

Reliable LC10/NOEC could be extracted, i.e. the LC10 of 4.1 μg/L for the endpoint mortality and the NOEC of 1.0 μg/L for the endpoint molting, as dissolved Ag.

The study is considered to be reliable and suitable for use for this endpoint.

Reference 6

Endpoint:

long-term toxicity to aquatic invertebrates

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:

14 d

Dose descriptor:

NOEC

Effect conc.:

0.16 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: molting

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Duration:

14 d

Dose descriptor:

EC10

Effect conc.:

1.02 µg/L

95% CI:

>= 0.18 - <= 5.71

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: molting

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

1.67 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Details on results:

The 14 day NOEC for Isonychia bicolor is 0.16 µg/L.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Dissolved Ag calculated based on mean recovery between unfiltered and filtered samples.
NOEC and LOEC values determined using Anova followed by Dunnett’s test, Tukey’s test or Kruskal-Wallis test. EC10 values were calculated based on the reported dose-response graphs using a logistic function (TRAP software).

Validity criteria fulfilled:

not applicable

Conclusions:

The 14 day NOEC for Isonychia bicolor is 0.16 µg/L.

Executive summary:

Phys-chem in the tests (DOC) is not reported; Estimation of dissolved Ag is based on a mean recovery rate, therefore not considering differences among measurements between samples; Reliable NOEC of 0.16 μg/L (molting) and 1.67 μg/L (mortality) could be extracted for I. bicolor as dissolved Ag. The EC₁₀value for molting of I. bicolor could not be retained because of the too wide (> factor of 10) confidence interval.

Although not a traditional endpoint, molting is indicative of effects on growth and valid for use as part of the overall dataset.

Reference 7

Endpoint:

long-term toxicity to aquatic invertebrates

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:

21 d

Dose descriptor:

NOEC

Effect conc.:

1.46 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Key result

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

0.84 µg/L

95% CI:

>= 0.34 - <= 2.13

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth

Remarks:

(weight)

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

4.4 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Details on results:

21 day NOEC growth (weight and length) is 2.6 μg total silver/L and the 21 day EC10 for growth (weight) is 1.68 µg/L.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Dissolved Ag calculated based on mean recovery between unfiltered and filtered samples.
NOEC and LOEC values determined using Anova followed by Dunnett’s test, Tukey’s test or Kruskal-Wallis test. EC10 values were calculated based on the reported dose-response graphs using a logistic function (TRAP software).

Validity criteria fulfilled:

yes

Conclusions:

The 21 day EC10 for growth (weight) is 0.84 µg/L.

Executive summary:

This study is a non-GLP, non-guideline study in which juvenile Corbicula were exposed in a 21 day static-renewal growth test.

Phys-chem in the tests (DOC) is not reported; Estimation of dissolved Ag is based on a mean recovery rate, therefore not considering differences among measurements between samples; ReliableEC₁₀/NOEC of 0.84 μg/L (growth) and 4.4 μg/L (mortality) could be extracted as dissolved Ag.

The study is considered to be reliable and suitable for use for this endpoint.

Reference 8

Endpoint:

long-term toxicity to aquatic invertebrates

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:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.59 µg/L

Nominal / measured:

estimated

Conc. based on:

element (dissolved fraction)

Remarks:

silver

Basis for effect:

mortality

Remarks on result:

other: dissolved Ag calculated based on mean recovery between unfiltered and filtered samples

Details on results:

Authors state that they are unable to obtain valid sublethal reproduction value due to insufficient number of offspring in test. No results included for acute tests.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

NOEC value determined using Anova followed by Dunnett’s test, Tukey’s test or Kruskal-Wallis test.

Validity criteria fulfilled:

not applicable

Conclusions:

The 21 day survival NOEC is 0.59 µg dissolved Ag/L.

Executive summary:

Phys-chem in the tests (DOC) is not reported; Estimation of dissolved Ag is based on a mean recovery rate, therefore not considering differences among measurements between samples; Reliable NOEC of 0.59 μg/L (mortality) could be extracted for H. azteca as dissolved Ag.

The study is considered to be reliable and suitable for use for this endpoint.

Reference 9

Endpoint:

long-term toxicity to aquatic invertebrates

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:

21 d

Dose descriptor:

EC10

Effect conc.:

5.37 µg/L

95% CI:

>= 2.89 - <= 7.12

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (total fraction)

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

12.01 µg/L

95% CI:

>= 9.79 - <= 14.95

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (total fraction)

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

4.08 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (total fraction)

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

8.33 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (total fraction)

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

3.49 µg/L

95% CI:

>= 1.98 - <= 4.49

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Remarks on result:

other: based on conventional dissolved Ag

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

6.97 µg/L

95% CI:

>= 5.81 - <= 8.44

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Remarks on result:

other: based on conventional dissolved Ag

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

5.03 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Remarks on result:

other: based on conventional dissolved Ag

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

2.52 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Remarks on result:

other: based on conventional dissolved Ag

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

0.059 µg/L

95% CI:

>= 0.022 - <= 0.088

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element

Basis for effect:

reproduction

Remarks on result:

other: Based on truly dissolved Ag

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

0.195 µg/L

95% CI:

>= 0.151 - <= 0.266

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element

Basis for effect:

reproduction

Remarks on result:

other: Based on truly dissolved Ag

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

0.163 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element

Basis for effect:

reproduction

Remarks on result:

other: Based on truly dissolved Ag

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.057 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element

Basis for effect:

reproduction

Remarks on result:

other: Based on truly dissolved Ag

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

3.97 µg/L

95% CI:

>= 1.7 - <= 5.4

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

immobilisation

Remarks on result:

other: based on conventional dissolved Ag

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

6.4 µg/L

95% CI:

>= 4.8 - <= 9.4

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth

Remarks:

length

Remarks on result:

other: based on conventional dissolved Ag

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

5 µg/L

95% CI:

>= 1.7 - <= 14.6

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: intrinsic rate

Remarks on result:

other: based on conventional dissolved Ag

Details on results:

- Observations on body length and weight: Adult body length showed significant differences between control and the two highest treatments.
- Other biological observations: There was a significant difference in survival of individuals between control and the highest treatments with silver nitrate. Thus, a concentration relating mortality of the adults was observed in the treatment with silver nitrate. No other clinical signs were observed in any replicate at any concentration tested. Neither any physical nor pathological symptoms were obtained.
- Mortality of control: There was 8% mortality in control.
- Particle size and zeta potential: The measurements of size and zeta potential revealed at all test concentrations that the chosen concentrations, which represented an optimal range for the growth test, were not sufficient for the size and zeta potential analysis. Especially the count rate of the size measurements indicated that the test concentrations were too low.

Results with reference substance (positive control):

24 h EC50 value (immobilization): 1.088 mg/L (95% CL: 0.632 – 1.841 mg/L)

Reported statistics and error estimates:

A LOEC was calculated by using ANOVA followed by Student-t test, Fisher's Exact Binomial test, Dunnett’s or Williams’ test or an appropriate non-parametric test. If no effect was observed up to the highest tested concentration the NOEC values were determined using appropriate statistical methods.
Since the test results of the reproduction test show a concentration-response relationship they were statistically analysed to determine an EC50, EC20 and EC10 value together with 95 % confidence intervals using Probit-analysis assuming log-normal distribution of the values.
Statistical calculations were done with the computer program ToxRat® Pro 3.2.1.

 Effective concentrations based on total Ag

Table 1: Percent reduction of survival, length and reproduction compared to controls after21 days.

Mean measured total Ag [µg Ag/L]	% reduction of survival (immobility)	% reduction of reproduction per introduced parent	% minimum detectable difference of age of first production	% decrease in length	% inhibition of intrinsic rate r
Control	8.3	0	0	0	0
0.95	16.7 (-)	6.5 (-)	7.5 (-)	-2.3 (-)	-1.6 (-)
1.99	0 (-)	1.0 (-)	7.8 (+)	1.0 (-)	3.8 (-)
4.08	0 (-)	5.5 (-)	7.9 (+)	2.1 (-)	6.6 (-)
8.33	25.0 (-)	22.7 (+)	8.0 (+)	6.2 (+)	5.4 (-)
18.8	66.7 (+)	79.0 (+)	9.7 (+)	15.9 (+)	36.3 (+)

(+) statistically significant difference between controls / (-) no significant difference between controls and treatments; Cochran-Armitage (survival), Williams Multiple Sequential t-test Procedure (reproduction, age of first reproduction and intrinsic rate), Multiple Sequentially-rejective Welsh-t-test after Bonferroni-Holm (Length); significance level 0.05, one-sided smaller.

 

 Table 2: Effective concentrations based on mean measured total Ag concentrations for the exposure of Daphnia magna for 21 days.

Mean measured test item concentrations [µg/L] - total Ag
Parameter^a		EC10	EC20	EC50	LOEC	NOEC
Immobility	Value	6.483	8.421	13.891	18.8	8.33
	95 %-cl lower	2.613	10.120	10.120
	95 %-cl upper	9.076	23.179	23.179
Reproduction	Value	5.37	7.08	12.01	8.33	4.08
	95 %-cl lower	2.89	4.56	9.79
	95 %-cl upper	7.12	8.85	14.95
Age of first reproduction	Value	0.0	0.0	0.0	1.99	0.95
	95 %-cl lower	0.0	0.0	0.0
	95 %-cl upper	0.0	0.0	0.0
Length	Value	10.93	31.90^b	247.59^b	18.8	8.33^a
	95 %-cl lower	8.05	20.04^b	89.65^b
	95 %-cl upper	16.40	87.10^b	n.d.
Intrinsic rate r	Value	9.53	13.18	24.51^b	18.8	8.33
	95 %-cl lower	0.06	1.30	18.88^b
	95 %-cl upper	13.27	16.83	n.d.

n.d.: not determined
^a: The NOEC for length was calculated to be at 40.8 µg Ag/L based on arithmetic mean measured concentrations of total Ag. However, due to the low inhibition of 6.2% at a concentration of 8.33 µg Ag/L, the NOEC was set to 8.33 µg Ag/L, since effects below 10 % compared to control are generally not considered to be ecotoxicologically relevant and it is generally recommended by OECD and EFSA to use the EC₁₀approach in preference to the NOEC approach for the environmental risk assessment .

^b: The value is above the highest test concentration of 18.8 µg Ag/L and therefore extrapolated.

Effective concentrations based on conventional dissolved Ag

 

Table 3: Percent reduction of survival, length and reproduction compared to controls after 21 days.

Mean measured conventional dissolved Ag [µg Ag/L]	% reduction of survival (immobility)	% reduction of reproduction per introduced parent	% minimum detectable difference of age of first production	% decrease in length	% inhibition of intrinsic rate r
Control	8.3	0	0	0	0
0.612	16.7 (-)	6.5 (-)	7.5 (-)	-2.3 (-)	-1.6 (-)
1.270	0 (-)	1.0 (-)	7.8 (+)	1.0 (-)	3.8 (-)
2.520	0 (-)	5.5 (-)	7.9 (+)	2.1 (-)	6.6 (-)
5.030	25.0 (-)	22.7 (+)	8.0 (+)	6.2 (+)	5.4 (-)
10.30	66.7 (+)	79.0 (+)	9.7 (+)	15.9 (+)	36.3 (+)

(+) statistically significant difference between controls / (-) no significant difference between controls and treatments; Cochran-Armitage (survival), Williams Multiple Sequential t-test Procedure (reproduction, age of first reproduction and intrinsic rate), Multiple Sequentially-rejective Welsh-t-test after Bonferroni-Holm (Length); significance level 0.05, one-sided smaller.

Table 4: Effective concentrations based on mean measured conventional dissolved Ag concentrations for the exposure of Daphnia magna for 21 days.

Mean measured test item concentrations [µg/L] – conventional dissolved Ag
Parameter^a		EC10	EC20	EC50	LOEC	NOEC
Immobility	Value	3.968	5.020	7.872	10.3	5.03
	95 %-cl lower	1.651	2.776	5.900
	95 %-cl upper	5.393	6.632	12.525
Reproduction	Value	3.49	4.43	6.97	5.03	2.52
	95 %-cl lower	1.98	2.96	5.81
	95 %-cl upper	4.49	5.40	8.44
Age of first reproduction	Value	0.0	0.0	0.0	1.27	0.612
	95 %-cl lower	0.0	0.0	0.0
	95 %-cl upper	0.0	0.0	0.0
Length	Value	6.35	17.33^b	118.47^b	10.3	5.03
	95 %-cl lower	4.76	11.14^b	44.99^b
	95 %-cl upper	9.37	46.36^b	n.d.
Intrinsic rate r	Value	5.76	7.60	12.90^b	10.3	5.03
	95 %-cl lower	n.d.	0.18	10.29^b
	95 %-cl upper	n.d.	9.41	n.d.

n.d.: not determined
^a:The NOEC for length was calculated to be at 2.52 µg Ag/L based on arithmetic mean measured concentrations of conventional dissolved Ag. However, due to the low inhibition of 6.2% at a concentration of 5.03.6 µg Ag/L, the NOEC was set to 5.03 µg Ag/L, since effects below 10 % compared to control are generally not considered to be ecotoxicologically relevant and it is generally recommended by OECD and EFSA to use the EC10 approach in preference to the NOEC approach for the environmental risk assessment .

^b: The value is about the highest test concentration of 10.3 µg Ag/L and therefore extrapolated.

 

 Effective concentrations based on truly dissolved Ag

 

Table 5: Percent reduction of survival, length and reproduction compared to controls after 21 days.

Mean measured truly dissolved Ag [µg Ag/L]	% reduction of survival (immobility)	% reduction of reproduction per introduced parent	% minimum detectable difference of age of first production	% decrease in length	% inhibition of intrinsic rate r
Control	8.3	0	0	0	0
0.020	16.7 (-)	6.5 (-)	7.5 (-)	-2.3 (-)	-1.6 (-)
0.024	0 (-)	1.0 (-)	7.8 (+)	1.0 (-)	3.8 (-)
0.057	0 (-)	5.5 (-)	7.9 (+)	2.1 (-)	6.6 (-)
0.163	25.0 (-)	22.7 (+)	8.0 (+)	6.2 (+)	5.4 (-)
0.269	66.7 (+)	79.0 (+)	9.7 (+)	15.9 (+)	36.3 (+)

(+) statistically significant difference between controls / (-) no significant difference between controls and treatments; Cochran-Armitage (survival), Williams Multiple Sequential t-test Procedure (reproduction, age of first reproduction and intrinsic rate), Multiple Sequentially-rejective Welsh-t-test after Bonferroni-Holm (Length); significance level 0.05, one-sided smaller.

Table 6: Effective concentrations based on mean measured truly dissolved Ag concentrations for the exposure of Daphnia magna for 21 days.

Mean measured test item concentrations [µg/L] – truly dissolved Ag
Parameter^a		EC10	EC20	EC50	LOEC	NOEC
Immobility	Value	0.126	0.153	0.221	0.269	0.163
	95 %-cl lower	0.010	0.030	0.161
	95 %-cl upper	0.169	0.195	0.389
Reproduction	Value	0.059	0.089	0.195	0.163	0.057
	95 %-cl lower	0.022	0.046	0.151
	95 %-cl upper	0.088	0.120	0.266
Age of first reproduction	Value	0.0	0.0	0.0	0.024	0.020
	95 %-cl lower	0.0	0.0	0.0
	95 %-cl upper	0.0	0.0	0.0
Length	Value	0.188	0.626^b	n.d.	0.269	0.163^a
	95 %-cl lower	0.131	0.348^b	n.d.
	95 %-cl upper	0.332	2.798^b	n.d.
Intrinsic rate r	Value	0.159	0.207	0.344 ^b	0.269	0.163
	95 %-cl lower	n.d.	n.d.	n.d.
	95 %-cl upper	n.d.	n.d.	n.d.

n.d.: not determined
^a:The NOEC for length was calculated to be at 0.057 µg Ag/L based on arithmetic mean measured concentrations of truly dissolved Ag. However, due to the low inhibition of 6.2% at a concentration of 0.163 µg Ag/L, the NOEC was set to 0.163 µg Ag/L, since effects below 10 % compared to control are generally not considered to be ecotoxicologically relevant and it is generally recommended by OECD and EFSA to use the EC10 approach in preference to the NOEC approach for the environmental risk assessment .

^b: The value is about the highest test concentration of 0.269 µg Ag/L and therefore extrapolated.

 

Validity criteria fulfilled:

yes

Remarks:

Mortality in controls was 8%; mean number of offspring in the control was 101/ female; dissolved O2 was > 3 mg/L; pH was within the range 6 - 9, and did not vary by more than 1.5 units; CV for the mean number of control offspring was 28.2 %.

Conclusions:

Based on mean measured total Ag concentrations the EC10 was 5.37 and 6.48 µg Ag/L for reproduction and immobility, respectively. The NOECs were 4.08 and 8.33 µg Ag/L for reproduction and immobility, respectively and LOECs were 8.33 and 18.80 µg Ag/L for reproduction and immobility, respectively.
Based on mean measured conventional dissolved Ag concentrations the EC10 was 3.49 and 3.97 µg Ag/L for reproduction and immobility, respectively. The NOECs were 2.52 and 5.03 µg Ag/L and LOECs were 5.03 and 10.30 µg Ag/L for reproduction and immobility, respectively.
Based on mean measured truly dissolved Ag concentrations the EC10 was 0.059 and 0.126 µg Ag/L for reproduction and immobility, respectively. The NOECs were 0.057 and 0.163 µg Ag/L and LOECs were 0.163 and 0.269 µg Ag/L for reproduction and immobility, respectively.

Executive summary:

The 21 day toxicity of silver nitrate to the test organism Daphnia magna was determined in a study according to the OECD 211 guideline. Daphnids were exposed to nominal concentrations of 1.5, 3.0, 6.0, 12.0 and 24.0 µg Ag/L in a semi-static system with renewal of test medium three times per week. The nominal test concentrations were prepared in modified Elendt M7 medium. The concentrations of the test item in the test media were determined by chemical analysis in the aqueous phase of all treatment levels by ICP-MS. The results were based on the arithmetic mean measured concentrations of total Ag, conventional dissolved Ag and truly dissolved Ag.

For PNEC derivation, reliable EC10 for D. magna on the endpoint immobility of 3.97 μg/L, on reproduction of 3.5 μg/L, on length of 6.4 μg/L, and on intrinsic rate of 5.0 μg/L could be extracted from this study. All data are expressed as conventional dissolved Ag.

This is a guideline, GLP- study and considered suitable for use as a key study for this endpoint.

Reference 10

Endpoint:

long-term toxicity to aquatic invertebrates

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:

7 d

Dose descriptor:

EC10

Effect conc.:

1.14 µg/L

95% CI:

>= 0.5 - <= 2.47

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Details on results:

The 7 day reproduction EC10 is 1.14 µg dissolved Ag/L

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

No data reported

Validity criteria fulfilled:

yes

Conclusions:

The 7 day reproduction EC10 is 1.14 µg dissolved Ag/L

Executive summary:

This is a non-GLP, long term toxicity study on Ceriodaphnia dubia following US-EPA (2002) guideline "Short-term methods for estimating the chronic toxicity of effluents and receiving waters to freshwater organisms". A reliable EC10 for reproduction of 1.14 (0.5-2.47) µg/L as dissolved Ag could be extracted.

The study is considered reliable and suitable for use for this endpoint.

Reference 11

Endpoint:

long-term toxicity to aquatic invertebrates

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:

7 d

Dose descriptor:

EC10

Effect conc.:

9.5 µg/L

95% CI:

>= 8.7 - <= 10.3

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Remarks on result:

other: HT+NOM study

Key result

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

10.1 µg/L

95% CI:

>= 7.3 - <= 13.8

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Remarks on result:

other: HT study

Key result

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

10.3 µg/L

95% CI:

>= 6.9 - <= 15.4

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Remarks on result:

other: mono study

Key result

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

11.5 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Remarks on result:

other: mass study

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

10.4 µg/L

95% CI:

>= 10.2 - <= 10.6

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: HT+NOM study

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

14.8 µg/L

95% CI:

>= 14.6 - <= 14.9

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: HT study

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

10.9 µg/L

95% CI:

>= 9.5 - <= 12.3

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: mono study

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

11.2 µg/L

95% CI:

>= 11.1 - <= 11.2

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: mass study

Details on results:

LC10 values of 10.4 μg/L, 14.8 μg/L, 10.9 μg/L and 11.2 μg/L (mortality) are calculated. For the endpoint reproduction, toxicity values of 9.5 μg/L, 10.1 μg/L, 10.3 μg/L and 11.5 μg/L are selected. EC10 values with too wide confidence interval (> factor of 10) were not further selected. All toxicity valus are expressed as dissolved Ag.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

All data are treated with analysis of variance (ANOVA) followed by Dunnett’s test. LC10/EC10 have been re-calculated using log-logistic distribution (TRAP software)

Validity criteria fulfilled:

yes

Conclusions:

LC10 values of 10.4 μg/L, 14.8 μg/L, 10.9 μg/L and 11.2 μg/L (mortality) are calculated. For the endpoint reproduction, toxicity values of 9.5 μg/L, 10.1 μg/L, 10.3 μg/L and 11.5 μg/L are selected. EC10 values with too wide confidence interval (> factor of 10) were not further selected. All toxicity valus are expressed as dissolved Ag.

Executive summary:

LC10 values of 10.4 μg/L, 14.8 μg/L, 10.9 μg/L and 11.2 μg/L (mortality) are calculated. For the endpoint reproduction, toxicity values of 9.5 μg/L, 10.1 μg/L, 10.3 μg/L and 11.5 μg/L are selected. EC10 values with too wide confidence interval (> factor of 10) were not further selected. All toxicity valus are expressed as dissolved Ag.

The study is considered reliable and suitable for use for this endpoint.

Reference 12

Endpoint:

long-term toxicity to aquatic invertebrates

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:

24 mo

Dose descriptor:

NOEC

Effect conc.:

5 µg/L

Nominal / measured:

not specified

Conc. based on:

element

Basis for effect:

reproduction

Details on results:

Larval releases in the parental stock of C. fornicata were significantly reduced in the 0.010 mg/L silver exposure group. The generation times, from egg to adulthood and first spawning of females at 0.001 and 0.005 mg/L were significantly different from controls. Females at 0.005 mg/L were significantly smaller than controls upon fist larval release. No differences were found in larval size at release for F1 C. fornicata.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

No data reported

Validity criteria fulfilled:

not specified

Conclusions:

The 2 year NOEC is 5 µg/L silver.

Executive summary:

C. fornicata was exposed for 24 month to silver as nitrate. 10 mated pairs of C. fornicata per concentration were exposed to 1, 5 and 10 µg Ag/L (1.34, 4.97 and 10.93 µg/L actual silver concentrations). After copulation and fertilization the females produced egg sacs, which allowed observation of developing larvae. The number of larval releases for each of 10 females from each test concentration of silver and controls was recorded for the entire test period. Fifteen larvae were then measured to determine their size at release. F1 larvae from each release of a single mating pair of the parental stock at each test concentration and control were held at the same silver exposure concentrations as the parents (15-25 °C). Each culture was changed daily. The larvae were reared through metamorphosis and the percentage that set was determined. F1 juveniles were maintained at ambient seawater conditions (4.5 - 25 °C) and at the same silver concentrations in which they were hatched. F1 juveniles were then reared to adulthood. A maximum of 10 mated pairs from each release of the single mated pair of parents was retained to observe fecundity. Results: Larval releases in the parental stock of C. fornicata were significantly reduced in the 0.010 mg/L silver exposure group. The generation times, from egg to adulthood and first spawning of females at 0.001 and 0.005 mg/L were significantly different from controls. Females at 0.005 mg/L were significantly smaller than controls upon fist larval release. No differences were found in larval size at release for F1 C. fornicata.

Reference 13

Endpoint:

long-term toxicity to aquatic invertebrates

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:

10 d

Dose descriptor:

NOEC

Effect conc.:

0.53 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

other: reproduction/mortality

Details on results:

Results with AgCl and Ag(SO2O3)nabove water solubility: 10d reproduction/survival NOEC 0.53 μg total Ag/L, 10d reproduction LOEC 1.14 μg total Ag/L and 96h and 10d LC50 0.92 (0.69 - 1.23) μg total silver/L.

Reported statistics and error estimates:

All data are treated with analysis of variance (ANOVA) followed by Dunnett’s test

Validity criteria fulfilled:

not specified

Conclusions:

10d reproduction/mortality NOEC is 0.53 μg dissolved silver/L.

Executive summary:

A 10 d reproduction test with Ceriodaphnia dubia resulted in a reliable NOEC for reproduction/mortality of 0.53 μg dissolved silver/L.

Reference 14

Endpoint:

long-term toxicity to aquatic invertebrates

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:

10 d

Dose descriptor:

NOEC

Effect conc.:

0.8 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

reproduction

Details on results:

10d reproduction NOEC 0.8 μg dissolved Ag/L

Reported statistics and error estimates:

All data are treated with analysis of variance (ANOVA) followed by Dunnett’s test

Validity criteria fulfilled:

not specified

Conclusions:

10d reproduction NOEC is 0.8 μg dissolved silver/L.

Executive summary:

A 10 d reproduction test with Daphnia magna resulted in a reliable NOEC for reproduction of 0.8 μg dissolved silver/L.

Reference 15

Endpoint:

long-term toxicity to aquatic invertebrates

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:

10 d

Dose descriptor:

NOEC

Effect conc.:

4 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Details on results:

10d mortality NOEC 4 μg dissolved Ag/L

Reported statistics and error estimates:

All data are treated with analysis of variance (ANOVA) followed by Dunnett’s test

Validity criteria fulfilled:

not specified

Conclusions:

10d mortality NOEC is 4 μg dissolved silver/L.

Executive summary:

A 10 d reproduction test with Hyalella azteca resulted in a reliable NOEC for mortality of 4 μg dissolved silver/L.

Reference 16

Endpoint:

long-term toxicity to aquatic invertebrates

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.:

19 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

dissolved

Basis for effect:

mortality

Remarks on result:

other: salinity 30‰

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	6.0	13	3.9	>3.2
20	34	60	60	5.8
30	19	37	35	9.3

Validity criteria fulfilled:

yes

Conclusions:

28 day NOEC mortality is 19 μg dissolved Ag/L (salinity 30‰)

Executive summary:

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

Reference 17

Endpoint:

long-term toxicity to aquatic invertebrates

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:

30 d

Dose descriptor:

NOEC

Effect conc.:

8.6 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

dissolved

Basis for effect:

other: development NOEC effects on spines

Details on results:

Adult NOEC 8.6 µg/L; adult LOEC 19 µg/L. 96 h LC50 40 µg/L. Fertilization EC50 14 µg/L (95% cf 12-16 µg/L)

Results with reference substance (positive control):

Not applicable

Validity criteria fulfilled:

yes

Conclusions:

30 day development NOEC effect on spines is 8.6 μg dissolved silver/L

Description of key information

Read across from ionic silver

Plus supporting data from a Daphnia magna study comparing the effects of the smallest nanosilver form registered under REACH previously (‘Nano 8.1’) and ionic silver (silver nitrate), demonstrating nanosilver is less toxic than ionic silver (based on EC10 and EC50 values)

Plus supporting published data from 2 studies on Daphnia magna included in the REACH dossier as Endpoint Study Records with various sizes of nanoparticles and coating types, showing that nanosilver is equally or less toxic than ionic silver

Additional information

Summary of available data for uncoated and coated nanosilver

Reliable and relevant data on the long-term toxicity of uncoated and coated nanosilver to invertebrates are available from three studies (Zhao and Wang 2011, Blinova et al. 2012, Schlich et al. 2017c,d).

Zhao and Wang (2011) report the effects on Daphnia magna growth and reproduction after exposure to uncoated nanosilver particles (20 nm) in a standard OECD 21 day reproduction test. The authors report that adult growth was significantly different from the control at the lowest concentration of nanosilver particles tested (5 µg/L). According to REACH guidance a NOEC of 2.5 µg/L can be derived from the LOEC (LOEC/2) as the effect observed at the LOEC was below 20%, relative to control response. Daphnia reproduction was unaffected at 5 µg/L but was significantly reduced at 50 µg/L. A parallel exposure to ionic silver (as silver nitrate) was conducted alongside the nanosilver experiments. However, no significant effects on survival, time to first brood, growth or reproduction were observed at the highest concentration tested (1.6 µg/L).

Blinova et al. (2013) also report the effects of exposure to nanosilver on Daphnia magna in an OECD standard reproduction test, but using natural test media rather than artificial water. NOECs of between 50 and 200 µg/L for two types of coated nanosilver: PVP and Collargol (protein) are reported. Aggregation of nanosilver particles was observed to occur in natural media, with protein coated particles aggregating to a lesser extent than PVP coated particles. Coating type was considered to influence aggregation behaviour to a greater extent than water physico-chemistry. In fact, the media effect on the particle size of aggregates was reported by the authors to be “unremarkable”.

The NOEC for Daphnia magna derived for nanosilver from Zhao and Wang (2011) is in the same order of magnitude as the EC10 of 2.14 µg/L for ionic silver reported for Daphnia magna in the REACH CSR (Bianchini and Wood 2008). The NOECs reported by Blinova et al. (2013) are an order of magnitude less sensitive than the EC10 for ionic silver used in the CSR.

Schlich et al. (2017 c,d) undertook comparative studies for nanosilver and silver nitrate with Daphnia magna. Schlich et al. (2017c) describes the long-term effects on Daphnia magna exposed to silver nitrate, while Schlich et al. (2017d) describes the long-term effects on Daphnia magna exposed to nanosilver. Both of these studies were conducted to OECD guideline 211 according to the principles of GLP, Both studies were conducted insynthetic, modified Elendt M7 medium, in which the trace elements and macro nutrients containing Cl^-were replaced by suitable elements containing nitrate (NO₃^-). EDTA was completely excluded from the test media, and to which the Daphnia were acclimated for at least 3 weeks prior to the studies. The nanosilver material used was a powder in aqueous suspension with the following particle size distribution: D25 = 7 nm, D50 = 8 nm, D75 = 9 nm (see section 4.5 of IUCLID), and contained 37% silver. The most sensitive end point in both tests was reproduction after 21 days. The EC10 values for reproduction for nanosilver were 33.4 (<0.45 µm) and 0.292 (<3kDa) µg/L measured dissolved silver. The comparable EC10 values for silver nitrate were 3.49 (<0.45 µm) and 0.059 (<3kDa) µg/L measured dissolved silver. Thus, the directly comparable EC10 values reported by Schlich et al (2017 c,d) were an order of magnitude more toxic for ionic silver than for nanosilver.

There is insufficient chronic data for aquatic invertebrates to investigate the influence of particle size of coating on the observed toxicity.