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Criteria and Standards for Drinking Water Quality
Published in Samuel D. Faust, Osman M. Aly, Chemistry of Water Treatment, 2018
Secondary MCLs, related to aesthetic effects, were set for two substances under Phase II (Table 1.8). An SMCL was established for aluminum at 0.05 to 0.2 mg/L to prevent post-precipitation of Al(OH)3 and discoloration of drinking water in distribution systems. An SMCL of 0.1 mg/L for silver was set for prevention of skin discoloration (argyria). Also, the USEPA considered setting SMCLs for seven organic chemicals under the Phase II rule.48 However, they deferred to the odor SMCL of TON 3, rather than set individual SMCLs over and above their MCLs for health reasons.36
Efficacy of copper and silver as residual disinfectants in drinking water
Published in Journal of Environmental Science and Health, Part A, 2019
Enue E. Sicairos-Ruelas, Charles P. Gerba, Kelly R. Bright
Both the EPA and the World Health Organization (WHO) regard silver as safe for human consumption. Only argyria, an irreversible but not dangerous skin discoloration, occurs with the ingestion of large quantities of silver (e.g., grams) over several years or by the administration of higher concentrations to ill individuals. Based on epidemiological and pharmacokinetic data, the WHO has determined a No Observable Adverse Effect Level (NOAEL) for humans of a maximum of 10 grams of silver over the course of a lifetime[71]. In the United States, no primary drinking water standard exists for silver; however, the EPA recommends a secondary non-enforceable standard of 100 μg/L [https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals; accessed April 2018]. The WHO has stated that this amount of silver for the treatment of water could easily be tolerated since the total absorbed dose would only be half of the NOAEL after 70 years[71].