The newspapers La Croix and La Voix du Nord report that tests carried out on ground water in the Nord - Pas-de-Calais have revealed unusually high concentrations of ammonium perchlorate. The chemical is used in a number of applications connected with pyrotechnics and explosives.
The fighting on the Western Front is being fingered as the root cause, but as the above map, from the newspaper La Voix du Nord, seems to show, the highest concentrations (the red) do not systematically follow the path of the front line. It may be blasting associated with the mining industry that may be at least partly to blame.