Tobacco is a tall, leafy annual plant, originally grown in South and Central America, but now cultivated throughout the world. Tobacco is an agricultural product processed from the fresh leaves of plants in the genus Nicotiana. Its most common usage is for smoking in the form of a cigarette or cigar. Tobacco is commercially available in dried, cured, and natural forms. Tobacco is the only crop grown in Pakistan whose yield is well above the world average and matches the per hectare yield in the US and other developed countries an average yield of 1,900 kilograms per hectare. In Pakistan, Tobacco was cultivated over an area of 6.2 million hectare with production of 126 thousand tons, during 2007 with an increase of 11.5 per cent production as compared to previous year. Tobacco growing, manufacturing, distribution and retailing employ over one million persons directly or otherwise. This translates in the full time equivalent of 312,500 jobs supporting approximately 1.2 million persons. Manufacturing employs the highest number of persons 35 per cent followed by 33 per cent by growing and 32 per cent in distribution and retail. Growing, manufacturing, distribution and retailing contributed 4.4 per cent or over R.s 27.5 billion to the total GDP of Pakistan including Rs 15.17 billion in excise duty and Rs 14.54 billion in sales tax in 1997. It is the only highest contributor of excise duty, six-times than that from cotton yarn. Over 5 per cent of all taxes collected in the country come from the tobacco industry. In view of the economic importance of tobacco, The Pakistan Tobacco Board was established in 1968. Before the establishment of Board, the balance of the trade was unfavorable, but now our exports outstripped imports. The Board has set up research stations at Mardan, Mansehra, Gujrat, Okara and Sahiwal with a zonal office at Lahore and head office in Peshawer. The purpose of these stations is to conduct research, solve local problems and convey information to the growers through the extension staff. Besides improving the quality and quantity of tobacco, the Board is extending the cultivation of tobacco to new suitable areas of the country. Nicotine, a powerful central nervous system stimulant found naturally in the tobacco leaf, is classified as a drug. Nicotine is one of the main ingredients in tobacco. It is poisonous and its higher dose is extremely dangerous. It is commonly used as an insecticide. Tobacco seeds are scattered onto the surface of the soil, as their germination is activated by light. Seedbeds are fertilized with wood ash or animal manure. Seedbeds are then covered with branches to protect the young plants from frost damage. These plants are left to grow until around April. After the plants have reached a certain height, they are transplanted into fields. This is originally done by making a relatively large hole in the tilled earth and then place the small plant in the hole. Various mechanical tobacco planters were invented throughout the late 19th and early 20th century to automate this process. Topping on tobacco is the removal of the terminal bud with or without some of the small top leaves just before or after the appearance of the flower head. Immediately after topping, the buds in the axis of the leaves, which otherwise remain dormant, become active and put forth shoots known as suckers. Since, like flowers, the suckers also become a drain on the nutrients of the plant, these are also removed. The removal of these suckers is called suckering or de-suckering. Topping reduces lodging, both by removing the seed head and by inducing development of stronger roots. It also increases the leaf area of the upper 1/3 of the plant and hastens leaf maturity. Topped plants have turgid leaves and can withstand greater moisture stress than non topped plants. For good retunes, only as many leaves should be left on the plant as are capable of maturing. For maximum yield under a given set of environmental conditions, a certain minimum number of leaves per hectare are required, irrespective of whether this number is obtained by high plant population and low topping or low plant population and high topping. Suckering is done either manually or by applying chemicals. If the growers and the industries both are to reap the benefits of these chemicals, suckericides should be put on the governments free import list are sufficient for domestic production arranged. Tobacco is harvested in one of two ways. In the oldest method, the entire plant is harvested at once by cutting off the stalk at the ground with a sickle. In the nineteenth century, bright tobacco began to be harvested by picking individual leaves off the stalk as they ripened. The leaves ripen from the ground upwards, so a field of tobacco may go through several "pickings" before the tobacco is entirely harvested, and the stalks may be turned into the soil. The first crop at the very bottom of the stalks are called "sand lugs", as they are often against the ground and are coated with dirt splashed up when it rains. Sand lugs weigh the most, and are most difficult to work with. Originally workers cropped the tobacco and placed it on animal-pulled sleds. Eventually tractors with wagons are used to transport leaves to the stringer, an apparatus which uses twine to sew leaves onto a stick. Some farmers use "tobacco harvesters" - basically a trailer pulled behind a tractor. The harvester is a wheeled sled or trailer that has seats for the croppers to sit on and seats just in front of these for the "stringers" to sit on. The croppers pull the leaves off in handfuls, and pass these to the "stringer", who loops twine around the handfuls of tobacco and hangs them on a long wooden square pole. Traditionally, the croppers, down in the dark and wet, with their faces getting slapped by the huge tobacco leaves, were men, and the stringers seated on the higher elevated seats were women. The harvester has places for four teams of workers, eight people cropping and stringing, plus a packer who takes the heavy strung polls of wet green tobacco from the stringers and packs them onto the pallet section of the harvester, plus a driver, making the total crew of each harvester 10 people. Interestingly, the outer seats are suspended from the harvester - slung out over to fit into the aisles of tobacco. As these seats are suspended it is important to balance the weight of the two outside teams (similar to a playground see-saw). Having too heavy or light a person in an unbalanced combination often results in the harvester tipping over especially when turning around at the end of a lane. Water tanks are a common feature on the harvester due to heat, and danger of dehydration for the workers. Salt tablets sometimes get used as well. Cut plants or pulled leaves are immediately transferred to tobacco barns (kiln houses), where they will be cured. Curing methods vary with the type of tobacco grown, and tobacco barn design varies accordingly. Air-cured tobacco is hung in well-ventilated barns and allowed to dry over a period of four to eight weeks. Fire-cured tobacco is hung in large barns where fires of hardwoods are kept on continuous or intermittent low smolder and takes between three days and ten weeks, depending on the process and the tobacco. Flue-cured tobacco was originally strung onto tobacco sticks, which were hung from tier-poles in curing barns. These barns have flues which run from externally fed fire boxes, heat-curing the tobacco without exposing it to smoke, slowly raising the temperature over the course of the curing. The process will generally take about a week. Curing and subsequent aging allows for the slow oxidation and degradation of carotenoids in tobacco leaf. This produces certain compounds in tobacco leaves very similar and give a sweet hay, tea, rose oil, or fruity aromatic flavor that contribute to the "smoothness" of the smoke. Un-aged or low quality tobacco is often flavored with these naturally occurring compounds. Tobacco flavoring is a significant source of revenue for the international multi-million dollar flavor and fragrance industry. The aging process continues for a period of months and often extends into the post-curing harvest process. After tobacco is cured, it is moved from the curing barn into a storage area for processing. For both cut and pulled tobacco, the leaves are then sorted into different grades. In colonial times, the tobacco was then "prized" into hogsheads for transportation. In bright tobacco regions, prizing was replaced by stacking wrapped "hands" into loose piles to be sold at auction. Today, most cured tobacco is baled before sales are made under pre-sold contracts. Tobacco water is a traditional organic insecticide used in domestic gardening. Tobacco dust can be used similarly. It is produced by boiling strong tobacco in water, or by steeping the tobacco in water for a longer period. When cooled the mixture can be applied as a spray, or 'painted' on to the leaves of garden plants, where it will prove deadly to insects. Topical tobacco paste is sometimes recommended as a treatment for wasp, hornet, fire ant, scorpion, and bee stings. An amount equivalent to the contents of a cigarette is mashed in a cup with about a 0.5 to 1 teaspoon of water to make a paste that is then applied to the affected area. Paste has a diameter of 4 to 5 cm (1.5 to 2 inches) and may need to be moistened in dry weather. If made and applied immediately, complete remission is common within 2030 minutes, at which point the paste can be removed. The next day there may be some residual itching, but virtually no swelling or redness. There seems to be no scientific evidence, as yet, that this common home remedy works to relieve pain. For about 2 percent of people, allergic reactions can be life-threatening and require emergency treatment. For more on this, see bee stings. Because of their nicotine addiction, many smokers find it difficult to cease smoking despite their knowledge of ill health effects. The main health risks in tobacco pertain to diseases of the cardiovascular system, in particular myocardial infarction (heart attack), diseases of the respiratory tract such as Chronic Obstructive Pulmonary Disease (COPD), asthma, emphysema, and cancer, particularly lung cancer and cancers of the larynx and tongue.