The following criteria are based on information presented in the technical appendix, and are summarized in the tables below. The Canadian Council of Ministers of the Environment (CCME) is considering similar guidelines for silver.
Summary Table
recommended criteria for the protection of
marine and freshwater aquatic life
Environment |
Criteria as total Silver |
Conditions | |
fresh water |
0.05 µg/L as a 30-day mean |
hardness 100 mg/L | |
0.1 µg/L maximum |
hardness 100 mg/L | ||
1.5 µg/L as a 30-day mean |
hardness > 100 mg/L | ||
3.0 µg/L maximum |
hardness > 100 mg/L | ||
marine water |
1.5 µg/L as a 30-day mean |
open coast and estuaries | |
3.0 µg/L maximum |
open coast and estuaries |
drinking water and food processing industries
For human, laboratory animal, wildlife and livestock drinking water, and for food processing industries where water is incorporated into the product, no silver criterion appears to be necessary. The aquatic life criteria are more than adequate for any such uses. The level used by Health and Welfare Canada in 1987, and by Australia in 1992, for human drinking water was 50 µg/L. Health and Welfare Canada deleted silver from the 1989 Guidelines for Canadian Drinking Water Quality as the value was very conservative and had no defensible, scientific basis.
recreation and aesthetics
Silver is not volatile, has no offensive odour and does not cause any colour or other visual effects in water, therefore it is not a concern for aesthetics. For recreation, levels of concern would be at least as high as, or higher, than the drinking water criterion. Therefore, no silver criterion appears to be necessary for these uses of the water. The aquatic life criteria are more than adequate for any such uses.
industrial
Industries, such as solid state electronics and photofinishing, which may have stringent silver requirements, may need to reduce silver concentrations in-house to levels suitable for their processes.