I don't believe that steroids will cause any testicular damage except in extreme abuse situations. The crazy Mr. Olympia style abuse is about 10 times normal testosterone levels.

Testicular shrinkage factor is not really common with moderate use and furthermore is just a temporary thing where your body figures it has enough testosterone so doesn't need more at the moment.

I've never seen any literature that mentions any permanent castration effect, at least at any doses that weren't so extreme as to be causing all sorts of other health problems.

Note that steroids generally have no adverse effects. At least they have less than pretty much any depression medication, allergy med, etc.

It is only that they are prone to abuse by guys with body image disorders. But you literally have to be pumping thousands of dollars worth of steroids into your body per week to get into those dangerous levels.

I have used rather large quantities of anabolic steroids over the past 15 years. I ran every cycle with what (in the power lifting world) would probably be described a moderate dose of testosterone —usually between 250 and 500 mg per week. This has always been combined with other anabolics (equipoise, trenbolone, dianabol, deca) and I’m fairly certain that my testicles are dead. My problem is that I “blast” (high levels of testosterone plus another anabolic) and then after 12-16 weeks, I “cruise” (lower the dosage of the testosterone back to 250 mg per week; no other anabolics) for the rest of the time. So basically, I haven’t produced any indigenous testosterone since I was in my late 20s. My testicles are roughly the size of olive pits and and hard. They do still have some feeling. A friend of mine is a urology nurse and he checked them out about a year ago. Based on what he saw and felt, plus information from me, that I would be lucky if they ever worked again. Furthermore, if I did cycle off to get them working that it would take 12-24 months of no testosterone for them to come back, assuming that they would. So, yes they will basically castrate you, especially over a long period of time.