Because non-communicable diseases are not passed from one person to another - communicable diseases are.
Toilet seats have almost zero impact on the spread of communicable disease. Although of course if there are smears on the seat you should clean it or use a different one, even in the case that you encounter disease on a seat, your skin is almost always an effective barrier between you and anything left there. You should be careful if you have open wounds on your buttocks, and shouldn't wipe the seat and then yourself with the same paper, but if you have an uncompromised immune system, a toilet seat should not be a dangerous thing. The most important thing is to wash your hands thoroughly.
When a person encounters a potentially dangerous situation, the hypothalamus in the brain signals the adrenal glands to release adrenaline and other hormones directly into the bloodstream.
The two factors that make biofilm in an intravenous line especially dangerous to the patient is infection and the difficulty of treatment. While the microorganisms are within the biofilm, they cannot be eradicated with antibiotics. However, if the biofilm were to detach from the IV line, the access to the circulatory system would potentially cause a massive infection.
It is dangerous because the animals can kill you if they are irritated.
92 bacteria are dangerous
All the seas are potentially dangerous
It is incorrect to assume that all chemicals are potentially dangerous or hazardous because that is not true.
Humans.
All explosives are potentially dangerous if the correct precautions are not taken.
Nefarious
Communicable diseases are diseases that are typically very dangerous and very contagious. Usually, diseases of this kind are spread by one person that catches the illness and unknowingly gives it to others.
probably a stall, but they are not that dangerous, if you are trained to get out of them
A wackjob is a crazy, potentially dangerous, person.
All dogs are potentially dangerous its mainly how there brought up.
If music is too loud, it can potentially damage the eardrums. This is why it's dangerous.
Natural gas is a potentially dangerous fossil fuel due to its combustibility
Tiger by the tail. means you are in a potentially dangerous position.