PARIS: A test run meant to allow Olympic athletes to familiarize themselves with the marathon swimming course in the Seine River was canceled Tuesday over concerns about water quality in the Paris waterway. World Aquatics made the decision to cancel the exercise at an early morning meeting, the organization said in a statement. Fluctuating bacteria levels in the long-polluted waterway have been a constant concern throughout the Games with the swimming portion of the triathlon and the marathon swimming events both planned in the river.