A federal agency wants to fine a Columbus manufacturer for safety violations. The Occupational Safety and Health Administration issued four safety citations against Columbus Castings. OSHA says the company has exposed workers to machine hazards at the South Parsons Avenue plant. In the latest incident in April, a worker suffered a broken back and other serious injuries when he was pinned by a hydraulic machine. The company makes steel castings for rail car manufacturers and other heavy industry. It recently announced a near doubling of its workforce. OSHA proposes a $90,000. The company has 15 business days to either pay the fine or file an appeal.