Tobacco

There are many types of tobacco. Nicotiana tabacum, or common tobacco, is the type used to make tobacco products such as cigarettes. About 90 per cent of the content of cigarettes is plant matter; the remaining 10 per cent is a combination of chemicals and other additives. Nicotine is a powerful central nervous system stimulant found naturally in the tobacco leaf and other plants. Nicotine is classified as a drug under Canada’s Food and Drugs Act.

Nicotine can be inhaled by burning tobacco leaves (in the form of cigarettes, cigars, pipes, etc.), or absorbed through the mouth in the form of smokeless tobacco (such as chew or snuff).

Aside from chemical fertilizers and pesticides used while growing tobacco, manufacturers also typically add compounds like ammonia to cigarettes. These compounds are commonly referred to as additives or flavourings. Tar, a term that refers to the solid particles found in tobacco smoke, is made of the by-products of burning tobacco and chemical additives. Tobacco smoke contains over 4,000 chemicals. At least 50 of them-including tar, nicotine, carbon monoxide, formaldehyde, hydrogen cyanide and benzene-are known cancer-causing agents.

Effects on general health

Cancer: Smokers are at increased risk of developing cancer. Common cancers related to smoking include cancers of the mouth, throat, pharynx, larynx (voice box), esophagus (food pipe), lungs, pancreas, kidney and cervix.

Lung disease: An estimated 85 per cent to 90 per cent of lung cancer is attributable to smoking. Smoking has also been known to cause chronic obstructive pulmonary diseases such as emphysema, bronchitis and asthmatic bronchitis.

Heart disease: Smokers are at increased risk for both stroke and cardiovascular disease, including high blood pressure and heart attack.

Gastrointestinal disease: There appears to be a link between smoking and the development of some stomach and digestive system disorders. Peptic ulcers (holes in the stomach or digestive tract) and Crohn’s disease (inflammation of the digestive tract) tend to be more common among smokers than non-smokers.

Effects on women's health

Reproduction and fertility: Smoking may have harmful effects on a woman's reproductive system and her ability to become pregnant.

• Women who smoke and use oral contraceptives (birth control pills) are at risk of developing serious cardiovascular side effects such as blood clots, heart attack or stroke.
• Smoking can lead to women having problems with becoming pregnant, and pregnant women who smoke are more likely than non-smokers to have a miscarriage or premature birth.
• Smoking may affect menstruation. Monthly periods can stop or be disrupted, and there is some evidence that smoking may destroy eggs in the ovaries, even in young women.
• Women who smoke are more likely to go through menopause early, meaning that their menstrual cycle, and therefore their ability to become pregnant, may end at an earlier age.

Women who smoke are at increased risk of developing osteoporosis, a condition in which the bones become thin and weak. There is some evidence that women are more likely than men to develop lung cancer and other respiratory diseases after the same levels of exposure to cigarettes. Women who smoke are more likely to develop cervical cancer than women who do not smoke. Women who smoke are at increased risk of developing cataracts.

Effects during pregnancy

There is no known safe level of tobacco consumption.

It is not clear whether a child's health problems are caused directly by a mother's use of tobacco during pregnancy or in combination with other factors including

• poor nutritional habits
• alcohol consumption
• using other drugs
• using more than one drug
• sleep problems
• a mother's general health prior to pregnancy
• genetics
• how much alcohol, tobacco or other drugs are consumed during pregnancy
• at what stage in the pregnancy a substance is consumed
• the length of time over which the substance is consumed

The effects of tobacco use have been difficult to study because these other factors also affect pregnancy. However, it is safest to avoid alcohol, tobacco and other drugs during pregnancy.

Nicotine and its metabolite, cotinine, are metabolized much more quickly by pregnant women than by non-pregnant women. This could mean that women who continue smoking into pregnancy may smoke more, thereby exposing the fetus to the dangerous health effects of tobacco more often.

Effects on the fetus

Carbon monoxide, nicotine and other chemicals in tobacco smoke enter the mother’s bloodstream and pass into the baby’s body. This affects the supply of food and oxygen a baby needs to grow. Therefore, a common effect of smoking during pregnancy is low birth weight of the infant.

Having a small baby does not mean labour and delivery will be easier. On the contrary, a smaller baby is not strong enough to help in its delivery, making the labour more difficult. Low-birth-weight infants are also more likely to suffer health and developmental complications throughout life, including delayed speech, cerebral palsy, visual and hearing difficulties, learning disabilities and respiratory problems.

Other increased risks for babies exposed to tobacco before birth include

• premature labour and delivery
• placenta abnormalities such as low-lying placenta or premature separation of the placenta from the wall of the uterus; each of these conditions can be serious for both mother and baby
• increased risk of spontaneous abortion, miscarriage, stillbirth and early infant death
• increased risk of sudden infant death syndrome (SIDS, or “crib death”)

Effects on breastfeeding

The nicotine in tobacco transfers into breast milk. This may affect the way breast milk smells and tastes, and may decrease the amount of milk produced by a nursing mother. Although nursing mothers who use tobacco should not be deterred from breastfeeding, quitting tobacco (and therefore eliminating nicotine from the mother’s breast milk) is best for both the baby and mother.

Effects on child development

Effects on long-term development

Children exposed to tobacco before birth may experience the negative effects of that exposure for years after they are born. Studies show that children are at increased risk for developmental and behavioural problems such as

• immature, aggressive, and oppositional or defiant behaviour
• inattention and impulsivity
• reduced lung functioning
• poor performance at school
• disruptive or impulsive behaviour
• depression and anxiety
• decreased motor, memory, language, creativity or reasoning skills
• developing alcohol or other drug problems as they get older

Evidence suggests that children of mothers who smoked during pregnancy are at increased risk of developing tobacco dependence later in their lives. Also, the transition from initial to daily use of cigarettes was more rapid for women who were exposed prenatally to tobacco. There is also growing evidence that children whose fathers smoked before conception are at risk of developing childhood leukemia as a result of genetic damage caused by tobacco exposure. This risk is higher for children whose mothers also smoked before conception, and children who are also exposed to second-hand smoke after birth.

Second-hand smoke

Second-hand smoke contains higher levels of tar, nicotine and carbon monoxide than inhaled cigarette smoke. Exposure to second-hand smoke, also called passive smoking, can cause problems during and after pregnancy.

Effects on children

• Mothers exposed to second-hand smoke during pregnancy tend to have pre-term births and low-birth-weight babies, even after a full gestation term.
• Low-birth-weight infants who are exposed to second-hand smoke after birth have an increased risk of developing respiratory illnesses.
• Incidence of sudden infant death syndrome (SIDS) is higher among infants who are exposed to second-hand smoke after birth.
• Children who live with smokers have an increased risk of developing conditions such as pneumonia, asthma, bronchitis and middle ear disease.

Effects on women

• Women exposed to significant amounts of second-hand smoke during pregnancy are more likely to give birth to low-birth-weight babies.
• Women, even if they do not smoke, are at risk of developing lung cancer and coronary heart disease when exposed to second-hand smoke.

Smokeless tobacco

Mothers who use smokeless tobacco during pregnancy are at risk of pre-term delivery and decreased infant birth weight, even at full gestational age. There are indications that using smokeless tobacco is just as harmful to fetal health as cigarette smoking.

Nicotine replacement therapy

It is not yet known whether nicotine replacement therapy (NRT) is safer for a fetus than tobacco exposure. Tobacco cessation as early as possible in a pregnancy is healthiest for both the mother and her fetus, but more research is needed to determine the effects of NRTs on an unborn child.

Tobacco cessation

Some people think that withdrawal from tobacco may be harmful to fetal health. However, quitting tobacco is healthiest for both the mother and infant, at any stage or time during pregnancy. Withdrawal is temporary; smoking, on the other hand, even just one cigarette a day, constantly exposes the mother and child to dangerous health risks.

It is never too late to quit using tobacco products. Studies show that infants of women who quit smoking in the first trimester have weight and body measurements similar to those among infants of mothers who never smoked during pregnancy. The negative health effects that may be caused by using smokeless tobacco, smoking or being exposed to second-hand smoke eventually disappear after quitting tobacco or eliminating exposure to second-hand smoke.