KRISHNA N. DAS and JENNIFER RIGBY AN unnamed middleman in Mumbai provided a crucial raw material used in Indian-made cough syrups that have been linked to the deaths of more than 70 children in Gambia, a chemicals trader involved in the supply chain told Reuters. The World Health Organization said last year the syrups, made by Indian manufacturer Maiden Pharmaceuticals Ltd, contained lethal toxins ethylene glycol (EG) and diethylene glycol (DEG) – used in car brake fluid. These ingredients can be used by unscrupulous actors as a substitute for propylene glycol (PG), which is a key base of syrupy medicines…