The CHEMDNER corpus of chemicals and drugs and its annotation principles

Abstract

The automatic extraction of chemical information from text requires the recognition of chemical entity mentions as one of its key steps. When developing supervised named entity recognition (NER) systems, the availability of a large, manually annotated text corpus is desirable. Furthermore, large corpora permit the robust evaluation and comparison of different approaches that detect chemicals in documents. We present the CHEMDNER corpus, a collection of 10,000 PubMed abstracts that contain a total of 84,355 chemical entity mentions labeled manually by expert chemistry literature curators, following annotation guidelines specifically defined for this task. The abstracts of the CHEMDNER corpus were selected to be representative for all major chemical disciplines. Each of the chemical entity mentions was manually labeled according to its structure-associated chemical entity mention (SACEM) class: abbreviation, family, formula, identifier, multiple, systematic and trivial. The difficulty and consistency of tagging chemicals in text was measured using an agreement study between annotators, obtaining a percentage agreement of 91. For a subset of the CHEMDNER corpus (the test set of 3,000 abstracts) we provide not only the Gold Standard manual annotations, but also mentions automatically detected by the 26 teams that participated in the BioCreative IV CHEMDNER chemical mention recognition task. In addition, we release the CHEMDNER silver standard corpus of automatically extracted mentions from 17,000 randomly selected PubMed abstracts. A version of the CHEMDNER corpus in the BioC format has been generated as well. We propose a standard for required minimum information about entity annotations for the construction of domain specific corpora on chemical and drug entities. The CHEMDNER corpus and annotation guidelines are available at: http://www.biocreative.org/resources/biocreative-iv/chemdner-corpus/.

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Affiliated Institutions

• Institute of Scientific and Technical Information CN
• National Central University TW
• Hokkaido University JP
• The University of Melbourne AU
• Institute of Scientific and Technical Information of China CN
• The University of Texas Health Science Center at Houston US
• University of Ljubljana SI
• Indian Institute of Technology Patna IN
• University College London GB
• Middle East Technical University TR
• Universidad de Navarra ES
• Indian Institute of Technology Madras IN
• Universitat de Lleida ES
• University of Lisbon PT
• Erasmus MC NL
• Universidad Politécnica de Madrid ES
• National Institutes of Health US
• Chungbuk National University KR
• Wuhan University CN
• Universidad Carlos III de Madrid ES
• Humboldt-Universität zu Berlin DE
• Taipei Medical University TW
• Pennsylvania State University US
• Spanish National Cancer Research Centre ES
• Hôpital de la Timone FR
• Harbin Institute of Technology CN
• Beijing Forestry University CN
• University of Aveiro PT
• National Center for Biotechnology Information US

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