Intravenous Injection of Chemotherapy. It is very common for chemotherapy medications to be injected into a vein, or intravenously. In many cases, a nurse or doctor will insert a needle into your vein, often in your hand or arm, and the chemotherapy will be given through there.
5. Box Jellyfish. The Box Jellyfish is arguably the world's most toxic animal and is responsible for over 5,000 human casualties over the past 50 years. These pestilent creatures reside mainly in the waters near Australia, Japan, Hawaii, and the Phillipines.
The bark is poisonous too -- burning it releases a smoke that causes temporary (and in some cases, permanent) blindness. Considering all the ways it can hurt you, it's no wonder the manchineel currently holds the Guinness record for world's most dangerous tree. Legend has it that one of the most infamous deaths by manchineel poison was of Spanish conquistador Juan Ponce de Leon.