How low is too low for LDL-c

For years the medical community has been at war with cholesterol. In the 50s and 60s it was total cholesterol that was thought to cause heart attacks. It was not found to be a reliable indicator of risk. We discovered some cholesterol containing particles (HDL)  were related to decreased risk of heart disease and some (LDL) increased. Drug companies developed drugs which lowered LDL pretty well.