Question: when did they start using pvc for plumbing
[{'answer': 'in the 1940s', 'provenance': [{'wikipedia_id': '43982', 'title': 'Plumbing', 'start_paragraph_id': 41, 'start_character': 266, 'end_paragraph_id': 41, 'end_character': 278, 'bleu_score': 1.0, 'section': 'Section::::Difference between pipes and tubes.:Materials.:Plastic.\n'}]}, {'provenance': [{'wikipedia_id': '43982', 'title': 'Plumbing', 'start_paragraph_id': 41, 'start_character': 0, 'end_paragraph_id': 41, 'end_character': 708, 'bleu_score': 0.818381150525276, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7165618734316150562}, 'section': 'Section::::Difference between pipes and tubes.:Materials.:Plastic.\n'}]}]