The government puts fluoride in our drinking water. What is the evidence that this is safe? We examine two studies that purport to show a connection between fluoride in our water and both thyroid disease and lower IQ. We also learn a little about so-called “ecological” studies, some stuff about statistics, and whose name is the earliest in recorded history. So let’s get our learn on, people.

Links from today’s episode:

• The full clip from Dr Strangelove
• Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water
• Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis
• Flawed study overstates link between fluoride and ill health: experts
• Water fluoridation and hypothyroidism: results of this study need much more cautious interpretation
• Debunking Unreliable Claims: The “Harvard study”
• The Birth of Writing: The Kushim Tablet