http://fluoridealert.org/ claims that "water fluoridation disproportionately harms low-income and minority communities" and is an Environmental Justice concern, and points out that 97% of western Europe has rejected fluoridation.
Fluoride Free NZ
http://fluoridefree.org.nz/ states, "The overwhelming body of scientific and statistical evidence does not support fluoridation." Particularly interesting is the article by the late Dr John Colquhoun at http://fluoridefree.org.nz/dr-colquhoun/
Global Healing Center
https://www.globalhealingcenter.com/natural-health/how-safe-is-fluoride/ warns of numerous dangers of fluoride exposure, including weakened skeletal health and toxicity to thyroid, and lowered IQ in children.
https://draxe.com/is-fluoride-bad-for-you/ states that fluoride can contain arsenic and "may cause damage to the brain and central nervous system"