Studies have found handwashing to cut risk of diseases like diarrhea and pneumonia by half, which otherwise kill a combined two million children a year.

FORBES: Can The Private Sector Drive Meaningful Social Progress? The Case of Global Handwashing Day

Smoking is estimated to kill more than one million Chinese a year.

CNN: China clouded in cigarette smoke

By contrast, humans kill around 100 million sharks every year - a number that has ballooned in recent years because of the enormous demand for shark fins to make shark fin soup.

CNN: Shark fin soup alters an ecosystem

Nearly 35, 000 people die a year from suicide, while another million people try to kill themselves.

FORBES: The Sick Patients Glaxo, Pfizer, and Lilly Refuse To Help