Triclosan

In vitro study
https://www.ncbi.nlm.nih.gov/pubmed/18655822
Triclosan decrease adenylyl cyclase enzyme, which decreases synthesis of cAMP, which decreases synthesis of testosterone.

Triclosan is found in Colgate Total toothpaste!!!!
http://www.colgatetotal.com/health-benefits/colgate-total-triclosan

From the New York Times… "Colgate Total is the only toothpaste in the United States that contains triclosan"
https://www.nytimes.com/2016/09/07/well/live/why-your-toothpaste-has-triclosan.html?_r=0

Triclosan reduced sperm production, LH and testosterone in rats
http://www.sciencedirect.com/science/article/pii/S089062380800364X

But… http://www.sciencedirect.com/science/article/pii/S0045653510010465