What diseases were there in the trench in World War 1? Trenche foot was very common in the trench warfare. caused from wet feet and not being able to change their socks and boots. Edit
Repels Sharks No.........human urine actually repells sharks and other fish.
1 Sharks can smell a drop of blood within a million drops of water or, in a slightly less scientific way, say a teaspoon of blood in an Olympic sized swimming pool and can smell blood hundreds of meters away.  Before sandpaper was developed shark skin was used to sand wood due to the rough dermal denticles.