Why you think its toxic? not more toxic than dbol I guess and its not even 17AA. Main reason to use injectible primo vs oral is bad bioavailability of orals. they simply doesnt work well. but very good for competitive sprinters and other athletes not looking for size gains.
Not only is the oral more toxic, but the absorption rate is somewhere between 40 and 50% of the injectible Primo, therefore you need twice as much in oral form to get same results, go for the injectible, save your liver, and money.