Danger is a different concept from Safety. Safety is related to Medicine. Medicine is related to Cotton. 
Maintenance is a synonym of Care. Care is related to Matter. Matter is related to Important. Important is related to Principal. 
Danger <--DistinctFrom--> Safety <--RelatedTo--> Medicine <--RelatedTo--> Cotton 
Maintenance <--Synonym--> Care <--RelatedTo--> Matter <--RelatedTo--> Important <--RelatedTo--> Principal 