Assessment of asbestos fiber contamination in lake sediment cores of the Thetford Mines region, southern Quebec (Canada)

•Lake sediments of the Thetford Mines region contain high asbestos concentrations.•Stratigraphic asbestos concentrations vary in accordance with mining history.•Asbestos mining waste erosion still today releases high amounts of asbestos fibers.•Asbestos fibers are transported over at least 25 km by the Bécancour River.