Review Articles
http://www.fluorideresearch.org/424/424/files/FJ2009_v42_n4_p260-276.pdf
Human Observational Studies
Cross-sectional study: Higher urinary flouride associated with lower testosterone in Chinese male farmers
https://www.ncbi.nlm.nih.gov/pubmed/27154732
Two-site study: Men from two areas of China, area with higher flouride in drinking water had lower testosterone
https://www.ncbi.nlm.nih.gov/pubmed/20364589
Findings: Men from the high flouride area had lower testosterone, but higher LH.
Limitations: They only looked at two areas and there could have been a great many other differences other than flouride alone.
Two-site study: Men from two areas of China, area with higher flouride in drinking water had lower testosterone
http://www.fluoridealert.org/wp-content/uploads/chen-1997.pdf
Similar to above, in results and caveats.
Case-control study: Cases of skeletal fluorosis have lower testosterone than controls
http://www.tandfonline.com/doi/abs/10.3109/15563659609013768
**Case-control study: A significant increase in FSH (P<0.05) and a reduction of inhibin-B, free testosterone, and prolactin in serum (P<0.05) were noticed in the HFEG.
http://www.sciencedirect.com/science/article/pii/S0013935103000598
Thyroid
More flouride, worse thyroid
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3890436/
Animal Studies
Management of fluoride induced testicular disorders by calcium and vitamin-E co-administration in the albino rat.
https://www.ncbi.nlm.nih.gov/pubmed/16769200
http://www.fluorideresearch.org/323/files/FJ1999_v32_n3_p162-170.doc
Flouride harms, but glutamine and glycine restore testosterone