National Drug Data File	Exposure Ontology	Source
http://purl.bioontology.org/ontology/NDDF/UN	http://purl.obolibrary.org/obo/ExO_0000066	LOOM
http://purl.bioontology.org/ontology/STY/T024	http://purl.obolibrary.org/obo/ExO_0000045	LOOM
http://purl.bioontology.org/ontology/STY/T025	http://purl.obolibrary.org/obo/ExO_0000046	LOOM