MARIETTA -  (WAOK/AJC)  Emergency responders are being treated after they were exposed to a potentially dangerous chemical,   during the discovery of a dead body found in a unit at the Jefferson Lakeside Apartments,  near Marietta.   Maintenance workers who found the deceased person were also quarantined,   as well as the occupant,   living in an adjacent apartment.   Cobb county emergency supervisors say the incident is one involving suicide by some kind of chemical cocktail,  but they have not revealed what kind of chemicals may have been used,  or the identity of the victim.   Firefighters were going door to door at the complex to make sure no one else was exposed.