your welcome. please post your findings and/or thoughts. i'd be interested.
the above first link from a UK news site is just a convenient one, further research suggested the same, it seemed like a good comprehensive one and possibly a credible outfit. (idk though, i'm not privy to UK news, us yanks are sheltered)
as far as synthetic drugs go with the way the rate they are popping up with everyone and their mother owning a chemistry set and using it with gold plated dollar (pound) signs in their eyes it's boggling. i do know that quiet a few are of cathinone relation; though some are synthetic cathinone and some are not. there are other ingredients that go into it that i'm more wary of.
i am not a synthetic user, i prefer the real thing. synthetics seem like a good idea but very bad in everyday use. (not judging anyone, i just don't like to eat other peoples faces for lunch. color me wrong.)
edit: a common misconception here in the states is that spice is bath salts. that's as far from the truth as one can get in most ways. spice is supposed to be a syunthetic marijuana, bath salts are supposedly to mimic more like cocaine, MDMDA/ecstasy or methamphetamine's. link provided to support this statement and why i personally don't use synthetics.
https://spiceaddictionsupport.org/what-is-spice/ (it's an american addiction recovery site. still not judging or preaching, just a firm belief to each their own.)