Stefan, all commercial chemicals have MSDS (US) or COHSS (EU) data sheets and even before these two systems data was published about the toxicity of these chemicals.

The toxicity of various photographic chemicals has been known about for a considerable period of time, and as such authors like Anchell & Troop would have access to a wide variety of sources. However they were not publishing a scientific or academic paper so had no call to cite sources.

Ian