Silver chloride

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.046 µg/L

Assessment factor:

3

Extrapolation method:

sensitivity distribution

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.86 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.025 mg/L

Assessment factor:

1

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

438.13 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

438.13 mg/kg sediment dw

Assessment factor:

10

Extrapolation method:

assessment factor

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

1.05 mg/kg soil dw

Assessment factor:

3

Extrapolation method:

sensitivity distribution

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

See CSR Annex 4 - PNEC Summary Report

Conclusion on classification

In the below table, the ERV values, TDp data (where applicable) and derived classifications (incl. M-factors) for silver compounds are summarised. Molecular weight of silver is 107.87.

Table 1: Basis for environmental classification of silver compounds, including reference to relevant figures/tables in CLP guidance (ECHA 2017).

Acute ERV = 0,00022 mg Ag/L

Chronic ERV = 0,0001 mg Ag/L

	Ag2O	AgNO3	AgCl	AgBr	AgI	Ag2SO4	Ag2CO3
MW (g)	231,74	169,87	143,32	187,77	234,77	311,8	275,75
classify as…	insoluble	soluble	soluble	soluble	soluble	soluble	soluble
TDp(7d;1 mg/L) in mg/L	0,053	/	/	/	/	/	/
TDp(28d;1 mg/L) in mg/L	0,062	/	/	/	/	/	/
TDp(28d;0.1 mg/L) in mg/L	0,0062*	/	/	/	/	/	/
Acute ERV (substance basis; mg/L)	0,00047	0,00035	0,00029	0,00038	0,00048	0,00064	0,00056
Chronic ERV (substance basis; mg/L)	0,00021	0,00016	0,00013	0,00017	0,00022	0,00029	0,000256
Acute classification	Acute 1	Acute 1	Acute 1	Acute 1	Acute 1	Acute 1	Acute 1
Chronic classification	Chronic 1	Chronic 1	Chronic 1	Chronic 1	Chronic 1	Chronic 1	Chronic 1
Acute M	100	1000	1000	1000	1000	1000	1000
Chronic M	10	100	100	100	100	100	100
*assuming 10x lower dissolution
Reference in CLP Guidance version 5.0 (July 2017)
Basis for classification - acute	Fig IV.4	Fig IV.4	Fig IV.4	Fig IV.4	Fig IV.4	Fig IV.4	Fig IV.4
Basis for classification - chronic	Fig IV.5	Fig IV.5	Fig IV.5	Fig IV.5	Fig IV.5	Fig IV.5	Fig IV.5
Basis for M acute	ratio TDp(7d;1mg/L) / ERV(acute)	Table IV.1	Table IV.1	Table IV.1	Table IV.1	Table IV.1	Table IV.1
Basis for M chronic	ratio TDp(28d;0.1mg/L) / ERV(chronic)	Table IV.1	Table IV.1	Table IV.1	Table IV.1	Table IV.1	Table IV.1

Acute and chronic ERV values for the silver ion 

Acute and chronic aquatic toxicity data are available for a range of different freshwater and marine species. For silver metal and silver compounds, the acute ecotoxicity reference value (ERV) is 0.22 µg Ag/L and the chronic ERV is 0.1 µg Ag/L.

In line with the risk assessment/classification approach adopted for other metals and inorganic metal compounds (ECHA 2017), ecotoxicity data are reported in terms of the concentration of dissolved silver ions from soluble inorganic silver species. Predominantly, these are studies that used silver nitrate (AgNO₃) as the source of dissolved silver ions. Silver nitrate is considered as the silver substance with the greatest toxicity as it dissociates rapidly and completely in aqueousmedia. Where data for silver nitrate was not available, data derived from other inorganic silver salts (e.g. silver chloride) were used, but only after the exposure conditions were determined to be acceptable (e.g. testing was conducted within the limits of solubility and the Ag+ ion was likely to be the dominant dissolved species).

A complete base set of acute ecotoxicity studies is available for soluble inorganic silver species, comprising numerous studies for fish, invertebrates and algae. The lowest reliable acute value is an EC50 of 0.22 µg Ag/L for the invertebrateDaphnia magna(pH 8.2, total organic carbon <0.1 mg/L; Bianchini et al. 2002).

A complete chronic data set is also available for soluble inorganic silver species, with chronic ecotoxicity data available for various species of fish, invertebrates and algae. The lowest reliable chronic value is an EC10 of 0.1 µg Ag/L for the algaePseudokirchneriella subcapitata(pH 7.2-8.5, DOC 0.38-0.88 mg/L; Fraunhofer 2017). Additional chronic toxicity data of similar sensitivity are also available forIsonychia bicolor(14-day NOEC of 0.16 µg Ag/L; Diamond et al, 1990),Salmo trutta(217-day EC10 of 0.23 µg Ag/L; Davies et al, 1998) andBrachionus calyciflorus(EC10 of 0.31 µg Ag/L; Arijs et al. 2021).

CONCLUSION: for the silver ion, the Acute ERV = 0.22 µg Ag/L and the Chronic ERV = 0.1 µg Ag/L.

Soluble silver compounds: environmental classification

The classification and labelling guidance states that if the solubility of a metal compound is greater than the L(E)C50 then it should be classified for acute and chronic hazard based on the available ecotoxicity data and the standard classification criteria. On 10th March 2011, Commission Regulation (EC) No 1272/2008 [CLP Regulations] was amended for the second time. The acute environmental classification is still based on acute data. However, the chronic environmental classification is now based on a chronic data set, if this is available. A complete chronic data set is available for silver and silver compounds.

Silver nitrate, silver chloride, silver bromide, silver iodide, disilver sulphate and disilver carbonate are classified as ‘soluble metal salt’. Since the acute ERV(recalculated on a substance basis using molecular weight conversion) is <1 mg/L for all soluble silver salts, they are all classified as aquatic acute category 1. The chronic ERV is <0.1 mg/L for all soluble silver salts, so they are all classified as aquatic chronic category 1 classification.

Under the CLP Regulations, an M factor must also be assigned to substances classified asaquatic acute/ chronic category 1.

For aquatic acute 1, the M-factor is based on the value of the acute ERV value (on a substance basis) and is determined as 1000 for all water-soluble Ag compounds.

For aquatic chronic 1, the M-factor is based on the value of the chronic ERV value (on a substance basis) and is determined as 100 (in absence of rapid environmental transformation) for all water-soluble Ag compounds.