I'm glad to see the two of you are aware of this problem. I want to specify something.

Fluoride /ˈflʊəraɪd/,[3] /ˈflɔːraɪd/[3] is an inorganic, monatomic anion of fluorine with the chemical formula F−. (wikipedia)

Fluorine is the element. Fluorine is present in the human body. It's the top 13 most present atom by weight. Like @kennyskitchen said one of the most used type of fluoride fed to people is hydrofluorosilic acid which is very toxic itself but is also filled with contaminant such as lead and arsenic. This isn't hidden.I provide a link to the epa.gov below stating just this but they state that the contaminant level are very low.

I would never ingest nor brush my teeth with fluoride whether it be food grade fluoride or fluoride coming from the toxic waste of the phosphate fertilizer industry.

I've read way too much on the subject to risk ingesting more fluoride than there is already everywhere. Here's just a tiny bit of what I read.

Harvard Study Finds Fluoride Lowers IQ - Published in Federal Gov't Journal | Reuters

In a meta-analysis, researchers from Harvard School of Public Health (HSPH) and China Medical University in Shenyang for the first time combined 27 studies and found strong indications that fluoride may adversely affect cognitive development in children. Based on the findings, the authors say that this risk should not be ignored, and that more research on fluoride’s impact on the developing brain is warranted.

EPA UNIONS CALL FOR NATIONWIDE MORATORIUM ON FLUORIDATION, CONGRESSIONAL HEARING ON ADVERSE EFFECTS, YOUTH CANCER COVER UP

WASHINGTON, DC, August 30, 2005 --/WORLD-WIRE/-- Eleven EPA employee unions representing over 7000 environmental and public health professionals of the Civil Service have called for a moratorium on drinking water fluoridation programs across the country, and have asked EPA management to recognize fluoride as posing a serious risk of causing cancer in people. The unions acted following revelations of an apparent cover-up of evidence from Harvard School of Dental Medicine linking fluoridation with elevated risk of a fatal bone cancer in young boys.

$750,000 Given In Childs Death In Fluorine Case (New York Times)

https://www.organicconsumers.org/old_articles/foodsafety/flouride090105.php
https://www.hsph.harvard.edu/news/features/fluoride-childrens-health-grandjean-choi/
https://www.cdc.gov/fluoridation/factsheets/engineering/wfadditives.htm
https://en.wikipedia.org/wiki/Composition_of_the_human_body#Elemental_composition_list
http://www.slideshare.net/benjaminyap/750000-given-in-childs-death-in-fluorine-case