2012: https://fluoridealert.org/content/50-reasons/

Highly recommend visiting the link for details about each point an references (it is not that long), here is a summary, don't comment if you haven't visited the link:

1) Fluoride is the only chemical added to water for the purpose of medical treatment.
2) Fluoridation is unethical.
3) The dose cannot be controlled.
4) The fluoride goes to everyone regardless of age, health or vulnerability.
5) People now receive fluoride from many other sources besides water.
6) Fluoride is not an essential nutrient.
7) The level in mothers’ milk is very low.
9) No health agency in fluoridated countries is monitoring fluoride exposure or side effects.
10) There has never been a single randomized controlled trial to demonstrate fluoridation’s effectiveness or safety.
11) Benefit is topical not systemic.
12) Fluoridation is not necessary.
13) Fluoridation’s role in the decline of tooth decay is in serious doubt.
14) NIH-funded study on individual fluoride ingestion and tooth decay found no significant correlation.
15) Tooth decay is high in low-income communities that have been fluoridated for years.
16) Tooth decay does not go up when fluoridation is stopped.
17) Tooth decay was coming down before fluoridation started.
18) The studies that launched fluoridation were methodologically flawed.
19) Children are being over-exposed to fluoride.
20) The highest doses of fluoride are going to bottle-fed babies.
21) Dental fluorosis may be an indicator of wider systemic damage.
22) Fluoride may damage the brain.
23) Fluoride may lower IQ.
24) Fluoride may cause non-IQ neurotoxic effects.
25) Fluoride affects the pineal gland.
26) Fluoride affects thyroid function.
27) Fluoride causes arthritic symptoms.
28) Fluoride damages bone.
29) Fluoride may increase hip fractures in the elderly.
30) People with impaired kidney function are particularly vulnerable to bone damage.
31) Fluoride may cause bone cancer (osteosarcoma).
32) Proponents have failed to refute the Bassin-Osteosarcoma study.
33) Fluoride may cause reproductive problems.
34) Some individuals are highly sensitive to low levels of fluoride as shown by case studies and double blind studies.
35) Other subsets of population are more vulnerable to fluoride’s toxicity.
36) There is no margin of safety for several health effects.
37) Low-income families penalized by fluoridation.
38) Black and Hispanic children are more vulnerable to fluoride’s toxicity.
39) Minorities are not being warned about their vulnerabilities to fluoride.
40) Tooth decay reflects low-income not low-fluoride intake.
41) The chemicals used to fluoridate water are not pharmaceutical grade.
42) The silicon fluorides have not been tested comprehensively.
43) The silicon fluorides may increase lead uptake into children’s blood.
44) Fluoride may leach lead from pipes, brass fittings and soldered joints.
45) Key health studies have not been done.
46) Endorsements do not represent scientific evidence.
47) Review panels hand-picked to deliver a pro-fluoridation result.
48) Many scientists oppose fluoridation.
49) Proponents usually refuse to defend fluoridation in open debate.
50) Proponents use very dubious tactics to promote fluoridation.