Tobacco smoke is hazardous because it contains a number of unhealthy chemicals, including some 60 carcinogens (cancer-causing agents), tar, arsenic, carbon monoxide and nicotine.

Arsenic containing compounds have been used as cancer treatment for hundreds of years.

Here a child in Nepal drinks from a well containing water contaminated with arsenic, which can lead to abnormal heart beat, blood vessel damage and cancer, among other ill effects.