That study was specifically on Australian firemen IIRC. Firemen are exposed to more of those particular chemicals because of their widespread use in flame retardant sprays.
As someone on similar medication for health reasons (severe testosterone deficiency), I can provide some more specific information that might be helpful.
The issue with testosterone is that it's linked to an increase in hematocrit (level of red blood cells in blood). There's a band of hematocrit levels that's healthy for donation. If the hematocrit level is too high, it's potentially dangerous to the recipient, but too low a level of hematocrit makes the donation dangerous to the donor. As a result, hematocrit level testing is one of the few tests that they do before every single donation.
These chemicals aren't dangerous, they're present in all humans. No blood clotting is hemophilia, which is also a dangerous condition. Regular blood donation can prevent build-up, and the decrease in hematocrit after blood donation is one of the reasons for the required interval between donations.
