Pyrovalerones are absolutely not per se toxic, neither to specific parts or the whole organism at once, but only some of them, just as some Phenetylamines are, but not the whole palette of them! MPHP is, for what I know, toxic to the liver while MDPHP on the other hand is not, just as the most potent NDRI known to man, to date, is nothing but far better to ones body as believers thought it is, reported it to be, which is funnily just the one that's the top-of-the-pops, the ultra, the one and only compound I know, that's exactly as poorly stigmatized, misunderstood and misinterpreted like Diamorphine, which is, needless to say: 3,4-Methylenedioxypyrovalerone (MDPV), to some the the powdered devil, that's coming with more bullhickey-trashtalk attached to it than bullhickey can carry, which's mostly just the faster-traveling infamously chosen portion of downsides whilst forgetting all the up-ones, the hollow paragraphs that are unfortunately of no real all-encompassing value/meaning/reality which is 100% true, that's in a serious way standing in a complete, contextual manner to it! I so wouldn't want to believe in those who say it's bad to shoot a Cathinone-derived Compound of the Pyrovalerone-Class that's not proven to be toxic, or bad in other ways to ones health - even though I think a-PHP is the one I wouldn't want to administer to myself as first-choice, but also not as the last...
I till today cannot really reprocess what I was thinking back when I decided to do so, but I did gave myself shots of MDPHP a few months ago, the intramuscular way, and am still alive with my deltoids just as fine as all my life, but since it did nothing in any thinkable way to prefer over plugging the stuff, but pose a greater risk to my body- and some of it's parts I wouldn't wanna risk to no advance, I'd say it's better using the more "common" routes of administration as shooting stuff which is reportedly even in it's impossible to beat best ways, meaning MDPV, known to provide no rush or something to consider worth the possible risks of intravenously introducing the body to a Compound...
I hope this helps?