Question: what enzyme system is linked to the metabolism of toxins and drugs
[{'answer': 'xenobiotic metabolism', 'provenance': [{'wikipedia_id': '1173475', 'title': 'Drug metabolism', 'start_paragraph_id': 1, 'start_character': 136, 'end_paragraph_id': 1, 'end_character': 157, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1173475', 'title': 'Drug metabolism', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 758, 'bleu_score': 0.9822204502117851, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17245323640366627307}, 'section': 'Section::::Abstract.'}]}]