The federal Mine Safety and Health Administration has cited six Kentucky mines for safety violations. Those mines were among the 19 nationwide that the agency inspected in May as part of their special impact inspections, which target mines with a history of compliance problems.At Perry County Coal Corporation’s E 4-2 Mine in southeastern Kentucky, federal inspectors found that the mine operator wasn’t maintaining dust collection systems, which are designed to protect miners from black lung disease. There were also ventilation problems, and the mine was cited for letting combustible materials accumulate near electrical equipment, which could lead to an explosion.MSHA began special impact inspections after the explosion last year at the Upper Big Branch Mine in West Virginia killed twenty-nine miners. The agency will release its conclusions about the causes of that explosion tomorrow.