Pesticide residues detected in Quebec drinking water

Analyses conducted by the organization Vigilance OGM in June have detected residues of metolachlor-ESA in the drinking water of several Quebec cities, including Châteauguay and Longueuil. The concentration of this substance, a byproduct of a pesticide used in corn and soy farming, exceeds the 0.1 microgram per liter (µg/L) threshold established by the European Union.

While the levels exceed European preventive standards, local authorities maintain that the water is safe. Châteauguay reported a concentration of 0.13 µg/L, stating the results represent “no quality issue” as they remain well below Quebec's established limits. Longueuil reported 0.147 µg/L and has requested an independent scientific opinion to clarify the findings.

Currently, Canada has no specific standard for metolachlor-ESA, though a standard of 35 µg/L exists for metolachlor. Health Canada is presently re-evaluating metolachlor and may update its reference values. Environmental health professor Maryse Bouchard has noted that the high presence of pesticides in various cities constitutes a public health concern.