Trachycephalus resinifictrix can produce a noxious secretion (thus the "milky" in their name) but you are probably thinking about Trachycephalus venulosus, a close relative which produces more potent excretions. I haven't heard of any problems with keepers, just wash your hands after handling them and make sure to avoid your eyes, mouth and nostrils (maybe this seems like common sense, but you never know). To be safe you probably shouldn't mix them with any other species. Having said that I know that the guy who bred my milkies kept his breeders in the same tank as his breeder mossies. Hope this helped.