NOT many smokers know what they are consuming when they light up a cigarette. The tobacco in cigarettes is usually blended from two types of tobacco leaves, which have about 2.5% to 4% nicotine. The cigarette is designed to deliver a steady dose of nicotine to the smoker.
In addition to the tobacco leaf, the cigarette contains fillers made from other parts of the tobacco plant and they are mixed with various flavours and additives. The additives increase the acceptability of the cigarette to the smoker as well as increase the addictiveness of cigarettes. The additives include sugars, which make it easier to inhale the smoke, and flavourings like mint. Some of these are harmless by themselves but when taken in combination with other substances, they may be harmful.
It is usual for the cigarettes, sold today, to have a filter at the mouth end. The filters, which are produced from cellulose, trap some of the smoke and tar from the inhaled smoke. Claims have been made that filtered brands contain less tar than others. There are also claims that they are safer because of the filters but these claims are poorly substantiated. But the fact remains that there is no such thing as a safe cigarette.
Tobacco smoke
The effects of cigarette smoking depend on the quantity smoked, type of cigarette and how the tobacco is prepared. There are two types of smoke from a cigarette: the mainstream smoke from the mouth end or filter, and the sidestream smoke from the burning tip of the cigarette. When a smoker inhales, the cigarette has been found to burn at 700°C at the tip and 60°C at the core. The tobacco is broken down to produce numerous chemicals, which are released into the atmosphere as invisible gases and particles, with the smoke making up 5% to 8% of a cigarette’s output. The gases include carbon monoxide, formaldehyde, hydrogen cyanide and dimethylnitrosamine. The particles include nicotine, benzene, benzopyrene and tar.
Most smokers are unaware of the uses of some of the gases and particles found in tobacco smoke. Formaldehyde is used to embalm the dead; acetone to remove nail varnish; benzene as a petrol additive; and cyanide in gas chambers during WWII.
Carbon monoxide, a toxic gas found in motor vehicle exhaust fumes, is present in all cigarette smoke. This poisonous gas attaches itself to the haemoglobin in the blood more readily than oxygen, thereby reducing the ability of the blood to carry oxygen. Britain’s Royal College of Physicians has reported a 15% reduction in the oxygen carrying capability of heavy smokers.
Nicotine is contained in the moisture of the tobacco leaf. When the cigarette is lit, the nicotine evaporates and attaches itself to the droplets in the tobacco smoke inhaled by the smoker.
It is absorbed very rapidly by the body and reaches the brain within 10 to 15 seconds. Nicotine stimulates the central nervous system and increases the heart rate and blood pressure, resulting in an increased need for more oxygen. Nicotine is a very powerful drug. When 60mg of pure nicotine is placed on an individual’s tongue, it kills within minutes. Nicotine causes addiction in the similar manner as heroin and cocaine. Nicotine deprivation leads to a strong craving, which is accompanied by anxiety, irritability, hunger, restlessness and decreased concentration.
All cigarettes produce tar in varying amounts. It is always taken into the body when a smoker inhales the smoke in a lit cigarette. The tar, which is composed of many chemicals, contains known cancer-causing agents (carcinogens). They include compounds like formaldehyde, arsenic, cyanide, benzopyrene, benzene, toluene and acrolein. When the tar condenses, it forms the sticky brown substance that stains the smokers’ teeth and fingers yellow brown.
Some of the contents of tobacco smoke are irritants and more than 50 of the compounds are carcinogens or toxins. A study, which was reported in the respected journal, Science, has established a link between smoking and lung cancer at the cellular level. Other substances are known or suspected mutagens that can cause permanent and harmful changes in the genetic materials in the cells.
Low-tar cigarettes
When it became known about half a century ago that the tar in the tobacco smoke was associated with an increased risk of lung cancer, a programme was established to gradually reduce the tar content of cigarettes. Studies from the United States report that the widespread usage of low-tar cigarettes has not prevented an increase in lung cancer among older male Americans. The presumed advantage of low tar cigarettes has been largely offset by an increase in the number of cigarettes smoked and/or deeper inhalation, because of the smokers’ need to compensate for the lower nicotine content in low tar cigarettes.
Pregnancy
The single most preventable cause of illness and death in mothers and infants is smoking. Female and male smokers have decreased fertility. The sperm quality of smokers is impaired with decreases in the count, motility and form. There may be erectile difficulties. It is believed that smoking affects sex hormone production in the female and egg transport in the fallopian tubes to the uterus.
A foetus gets all its nutrients and oxygen from the pregnant woman via the placenta and umbilical cord. A pregnant woman exposed to tobacco smoke will transmit the toxins in it to the foetus. The carbon monoxide content of foetal blood is increased leading to it containing less oxygen than normal, which means that the foetal heart has to beat harder on every occasion the pregnant woman inhales tobacco smoke. The toxins of tobacco smoke also affects placental function and hence, foetal nutrition.
Women who smoke during pregnancy are at increased risk of miscarriage and stillbirth. They have double the risk of premature rupture of the membranes, placental abruption and placenta praevia, all of which can lead to prematurity and even stillbirth.
The babies of mothers exposed to tobacco smoke are at increased risk of prematurity and low birth weight, that is, below 2.5kg. Their babies’ organs are smaller than that of non-smokers’ babies. These babies’ lung function is poorer and they are more likely to get middle ear infections and asthmatic bronchitis in early childhood. Their likelihood of cot death (sudden infant death syndrome) is increased by 1.5 to 3 times. They are sick more often than babies of non-smokers. In addition, the babies are more likely to become smokers when they grow up.
Cessation
It is never too late to cease smoking. The damage from smoking can be reversed when there is cessation of smoking. There is evidence that women who cease smoking in mid-pregnancy gave birth to babies with the same average birth weight as non-smokers. Many women smokers ceased smoking during their pregnancies and never smoked again.
The greatest gift that a pregnant smoker can give to her unborn child is to cease smoking. It is important to remember that the foetus is totally dependent on the mother to prevent toxins from poisoning him or her.
Dr Milton Lum is a member of the board of Medical Defence Malaysia. This article is not intended to replace, dictate or define evaluation by a qualified doctor. The views expressed do not represent that of any organisation the writer is associated with.
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