Draft technical document guidelines for Canadian drinking water quality - Antimony: Rationale for maximum acceptable concentration

Antimony naturally occurs in the environment in the form of organic and inorganic compounds. Antimony enters the environment from natural emissions and anthropogenic activities, with coal combustion, mining and smelting being the most important sources of anthropogenic release. Antimony may enter drinking water from plumbing solders in drinking water distribution systems.

Oral exposure to antimony may induce adverse effects mainly on the gastrointestinal tract and the liver. Kidney, cardiovascular, metabolic and developmental adverse effects have also been reported in the literature.

The derivation of the HBV of 0.003 mg/L (3 ug/L) is based on a form of antimony that is more soluble (and thus more bioavailable) than those forms occurring in drinking water. Therefore, reducing the current MAC of 0.006 mg/L (6 ug/L) to the updated HBV is not expected to significantly increase health protection. Given this fact and the anticipated treatment challenges associated with lowering the MAC, particularly for private wells and for small systems, the Federal-Provincial-Territorial Committee on Drinking Water is proposing a risk managed approach which would reaffirm the MAC of 0.006 mg/L (6 µg/L) for antimony in drinking water.

The proposed MAC is expected to be protective of all forms of antimony in drinking water. As part of its ongoing guideline review process, Health Canada will continue to monitor new research in this area and recommend any changes to this guideline technical document that it deems necessary.

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