There was a chemical that Noriega used when the civil population came out against him en mass. Water tank trucks would come on the scene and hose the crowds down with a watery liquid that had a red color. A doctor was telling me that it caused pain, burned the skin, and medical staff who touched the liquid on the patients were also injured if they didn't have gloves or something on.
My guess it was sulfuric acid and that the trucks were manned by the Cubans and Nicaraguans he had in Panama. Strange-- I never heard Amnesty or the press ever complain about it.