A maximum acceptable concentration (MAC) of 0.05 mg/L (50 µg/L) is proposed for diquat (measured as the cation) in drinking water. Any exceedance of the proposed MAC should be investigated and followed by the appropriate corrective actions if required.
Diquat is an herbicide that is applied to food crops and to water sources for weed control. The general Canadian population is therefore potentially exposed to diquat through food, and to a lesser extent, through drinking water. In 2016, more than 500,000 kg of diquat (as active ingredient) was sold in Canada. Very low levels of diquat have been detected in foods. Data provided by provinces and territories that monitor for diquat in source and drinking water indicate that levels of diquat are below the detection limit.
Health effects: In repeat-dose animal studies, diquat primarily targeted the eyes, causing cataracts, and also affected the kidneys and liver. The proposed MAC of 0.05 mg/L (50 µg/L) is based on cataract formation
CWWA’s Drinking Water Quality Committee is reviewing the proposal to determine if the Association should submit comments on the proposed Guidelines.
Access the Gazette Notice at:
http://gazette.gc.ca/rp-pr/p1/2020/2020-07-04/html/notice-avis-eng.html#nb2
Canadian Water and Wastewater Association