Arsenic and prostate cancer
In fiction, arsenic is best known as a poison; the metal is so notorious that it's been called the king of poisons. In fact, arsenic has been used by so many members of royal households that it's also been called the poison of kings. But arsenic is much more than a murderer's tool. In the past, it was used to treat a variety of illnesses, ranging from sleeping sickness and syphilis to psoriasis and leukemia. It was also used in many pesticides. And even though medicinal and agricultural uses of arsenic have been largely abandoned, the metal still has a variety of industrial uses; the list includes wood preservatives, lead-acid batteries, automotive body solder, and semiconductor applications.
Arsenic is also widely distributed in the environment. Natural deposits are present in soil and rocks; high levels are found near industrial sites and hazardous waste sites. And arsenic can run off from soil and industrial waste to enter drinking water, making the infamous metal a concern for everyone.