Found a study about it here...
http://www.aensi.org/aeb/2007/39-43.pdf
Conclusion taken from study....
"The outcome of this investigative experiment
shows that stanozolol and trenbolone have the
potential to be genotoxic and cytotoxic, especially at
40 and 60 mM, with or without metabolic activation,
in cultured human lymphocytes. The evaluation of
these genotoxicity tests is a useful tool for
determining the toxic effects of potentially genotoxic
chemicals, leading to identification of such
carcinogenic agents. It is advisable to use the steroids
studied here at their lowest effective dosage so that
the risk to public health could be minimized. The
risk of damage to human genetic material is very
likely at higher doses of these drugs."
Read it today and don't know what to think of it, especially with that last sentence.