NTP RESEARCH REPOrt ON SYSTEMATIC LITERATURE REVIEW ON THE EFFECTS OF FLUORIDE ON LEArnING AND MEMORY IN ANIMAL STUDIES NTP RR 1 JULY 2016 NTP Research Report on Systematic Literature Review on the Effects of Fluoride on Learning and Memory in Animal Studies Research Report 1 July 2016 National Toxicology Program Public Health Service U.S. Department of Health and Human Services ISSN: 2473-4756 Research Triangle Park, North Carolina, USA Systematic Literature Review on the Effects of Fluoride on Learning and Memory in Animal Studies Table of Contents Tables ............................................................................................................................................. iv Figures............................................................................................................................................ iv About This Report............................................................................................................................v Peer Review ................................................................................................................................. viii Protocol Review ........................................................................................................................... viii Publication Details ......................................................................................................................... ix Abstract ............................................................................................................................................x Introduction ......................................................................................................................................1 Sources of Exposure ....................................................................................................................1 Use of Fluoride to Prevent Tooth Decay.....................................................................................1 Concerns for Potential Fluoride Toxicity ....................................................................................2 Objectives and Research Strategy ...............................................................................................4 Research Strategy.................................................................................................................4 Methods............................................................................................................................................5 Development of Research Question ............................................................................................5 Literature Search Strategies ........................................................................................................5 Searching Electronic Databases ...........................................................................................5 Searching Other Resources ..................................................................................................6 Selection Criteria for the Evidence .............................................................................................6 Data Collection and Presentation ................................................................................................7 Data Extraction ....................................................................................................................7 Quality Assessment of Individual Studies ...........................................................................7 Evidence Synthesis ..............................................................................................................9 Assessment of Confidence in the Body of Evidence .........................................................10 Preparation of Level-of-evidence Conclusions ..................................................................13 Results ............................................................................................................................................14 Literature Search Results ..........................................................................................................14 Overview of Included Studies ...................................................................................................21 Behavioral Tests for Learning and Memory ......................................................................22 Effects of Fluoride on Learning and Memory...........................................................................27 Evidence Synthesis ............................................................................................................27 Exposure during Development ..........................................................................................27 Exposure during Adulthood ...............................................................................................36 Exposure at Less Than 4 ppm ............................................................................................51 Quality of Evidence ...........................................................................................................56 Discussion ......................................................................................................................................58 Summary ...................................................................................................................................58 Relevance to Human Exposure Levels .....................................................................................58 Limitations in the Literature Base .............................................................................................60 Limitations of the Systematic Review ......................................................................................60 ii Systematic Literature Review on the Effects of Fluoride on Learning and Memory in Animal Studies Data Gaps and Research Needs.................................................................................................62 Conclusion ................................................................................................................................62 References ......................................................................................................................................64 Appendix A. Electronic Database Search Strategies .................................................................. A-1 Appendix B. Data Extraction Elements for Animal Studies........................................................B-1 Appendix C. Studies Excluded from the Analysis for Having “Probably High” or “Definitely High” Risk of Bias in Multiple Critical Domains ...............................C-1 Appendix D. Learning and Memory: Morris Water Maze (All Studies) .................................... D-1 Appendix E. Learning and Memory: T-Maze.............................................................................. E-1 Appendix F. Learning and Memory: Y-Maze ............................................................................. F-1 Appendix G. Learning and Memory: Other Maze Tests ............................................................ G-1 Appendix H. Learning and Memory: Exploratory Behavior ...................................................... H-1 Appendix I. Learning and Memory: Passive Avoidance .............................................................. I-1 Appendix J. Learning and Memory: Active Avoidance ............................................................... J-1 Appendix K. Motor and Sensory Function: Locomotor Activity ............................................... K-1 Appendix L. Motor and Sensory Function: Movement Coordination ......................................... L-1 Appendix M. Motor and Sensory Function: Reflex and Motor Sensory Development ............. M-1 Appendix N. Anxiety .................................................................................................................. N-1 Appendix O. Grooming, Defecation, Urination.......................................................................... O-1 Appendix P. Sexual Behavior ...................................................................................................... P-1 Appendix Q. Territorial Aggression ........................................................................................... Q-1 Appendix R. Other .......................................................................................................................R-1 Appendix S. Fluoride Administered and Converted Doses (Individual Studies) ........................ S-1 Appendix T. Fluoride Administered and Converted Doses (Range across Studies for a Given ppm Level) ................................................................................................... T-1 Appendix U. Pharmacokinetics and Concentrations of Fluoride Measured in Tissue, Blood, Urine, or Bone ........................................................................................... U-1 Appendix V. Background Fluoride Levels in Drinking Water and Diet .................................... V-1 iii Systematic Literature Review on the Effects of Fluoride on Learning and Memory in Animal Studies Tables Table 1. Representative Values for Fluoride Intakes Used in Calculation of the Relative Source Contribution from Drinking Water ........................................................................1 Table 2. PECO (Populations, Exposures, Comparators, Outcomes) Statement ..............................5