Complex sentence: Proper hand washing after handling should prevent any problems with infection from Salmonella (which newts are known to carry) or ingestion of TTX, however, some individuals are known to be allergic to contact with the toxin.
Split into simpler sentences: Proper hand washing after handling should prevent any problems with infection from Salmonella (which newts are known to carry) or ingestion of TTX. However, some individuals are known to be allergic to contact with the toxin.