Tobacco is a temperate crop which is grown in more than 100 countries world-wide, mostly in developing countries.
China is the world's largest producer, followed by the USA, India, Brazil and Turkey.
In 1994, these five countries produced nearly two-thirds of global output. The effects of these chemicals are not monitored generally but it is known that they leach into the soil and find their way into streams, rivers, and food chains. These substances may indirectly cause the genetic selection of pesticide-resistant mosquitoes or flies, making the control of diseases such as malaria much more difficult. This involves slowly drying the tobacco leaf in hot air produced by the controlled burning of wood. In the traditional tobacco barns made from mud and thatch, found in many parts of Africa, the efficiency of the curing process is extremely low.