QUOTE The increased risk to non-smokers of lung cancer from secondhand smoke (SHS) was estimated at 24% ...

New studies on SHS exposure and the risk of heart disease have strengthened the findings of the 1998 SCOTH overview which estimated that the excess risk in non smokers exposed to SHS compared to those not exposed was 23%. We now have greater understanding of the ways in which tobacco smoke inhalation damages the blood vessels. Whereas lung cancer risk increases in a linear fashion with the number of cigarettes smoked and the duration of smoking, damage to the heart and the arteries occurs disproportionately at the lower exposures experienced by those exposed to SHS. ..

... Children are at greatest risk in their homes and the evidence strongly links SHS with an increased risk of pneumonia and bronchitis, asthma attacks, middle ear disease, decreased lung function and sudden infant death syndrome. It has also been shown that babies born to mothers who come into contact with SHS have lower birth weights.

Overall exposure to secondhand tobacco smoke in the population has declined somewhat as cigarette smoking prevalence has continued to come down. However, some groups, for example bar staff, are heavily exposed at their place of work and almost half of all children still live in households with at least one smoker.

QUOTE Nonsmokers are exposed to the same carcinogens as active smokers. Even the typical levels of passive exposure have been shown to cause lung cancer among never smokers. Second-hand tobacco smoke IS carcinogenic to humans.

QUOTE Environmental tobacco smoke (ETS) is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans that indicate a causal relationship between passive exposure to tobacco smoke and human lung cancer. Studies also support an association of ETS with cancers of the nasal sinus.

...Many studies, including recent large population-based case control studies, have demonstrated increased risks of about 20% for developing lung cancer following prolonged exposure to ETS, with some studies suggesting higher risks with higher exposures. Exposure to ETS from spouses smoking or exposure in an occupational setting appears most strongly related to increased risk.

QUOTE Exposure to environmental tobacco smoke is a cause of lung cancer and, in those with long term exposure, the increased risk is in the order of 20-30%.

Exposure to environmental tobacco smoke is a cause of ischaemic heart disease and, if current published estimates of magnitude of relative risk are validated, such exposure represents a substantial public health hazard.

Smoking in the presence of infants and children is a cause of serious respiratory illness and asthmatic attacks.

Sudden infant death syndrome, the main cause of post-neonatal death in the first year of life, is associated with exposure to environmental tobacco smoke. The association is judged to be one of cause and effect.

Middle ear disease in children is linked with parental smoking and this association is likely to be causal.

QUOTE The review of the scientific evidence found positive associations between passive smoking and the following diseases: asthma in children, lower respiratory illness, lung cancer, major coronary events and other illnesses.

QUOTE Based on the weight of the available scientific evidence, EPA has concluded that the widespread exposure to environmental tobacco smoke in the U.S. presents a serious and substantial public health risk.

In adults:

ETS is a human lung carcinogen, responsible for approximately 3,000 lung cancer deaths annually in U.S. non-smokers. ETS has been classified as a Group A carcinogen under EPA's carcinogen assessment guidelines. This classification is reserved for those compounds or mixtures which have been shown to cause cancer in humans, based on studies in human populations.

In children:

ETS exposure increases the risk of lower respiratory tract infections such as bronchitis and pneumonia. EPA estimates that between 150,000 and 300,000 of these cases annually in infants and young children up to 18 months of age are attributable to exposure to ETS. Of these, between 7,500 and 15,000 will result in hospitalization.

ETS exposure increases the prevalence of fluid in the middle ear, a sign of chronic middle ear disease.

ETS exposure in children irritates the upper respiratory tract and is associated with a small but significant reduction in lung function.

ETS exposure increases the frequency of episodes and severity of symptoms in asthmatic children. The report estimates that 200,000 to 1,000,000 asthmatic children have their condition worsened by exposure to environmental tobacco smoke.

ETS exposure is a risk factor for new cases of asthma in children who have not previously displayed symptoms.

QUOTE Environmental tobacco smoke (ETS) is potentially carcinogenic to occupationally exposed workers.

Research on the toxicity and carcinogenicity of tobacco smoke has demonstrated that the health risk from inhaling tobacco smoke is not limited to the smoker, but also includes those who inhale ETS.

[Authoritative] reviews estimated the relative risk of lung cancer to be approximately 1.3 for a non-smoker living with a smoker compared to a non-smoker living with a non-smoker.

Recent evidence suggests a possible association between exposure of non-smokers to ETS and an increased risk of heart disease.

By 1986, 15 years ago, there was strong consensus that Secondhand smoke causes lung cancer, and respiratory problems in children:

QUOTE 1. Involuntary smoking is a cause of disease, including lung cancer, in healthy non-smokers.

2. The children of parents who smoke, compared with the children of non-smoking parents, have an increased frequency of respiratory infections, increased respiratory symptoms, and slightly smaller rates of increase in lung function as the lung matures.

3. Simple separation of smokers and non-smokers within the same air space may reduce, but does not eliminate, exposure of non-smokers to environmental tobacco smoke.

QUOTE Considering the evidence as a whole, ETS increases the incidence of lung cancer in non-smokers.

Since children exposed to ETS from parental smoking have an increased frequency of pulmonary symptoms and respiratory infections, it is prudent to eliminate ETS exposure from the environments of small children.

QUOTE There is strong evidence to suggest that maternal smoking after birth is associated with increased diseases of the lower respiratory tract for the first year of life.

Council notes that the epidemiological evidence shows that inhalation of passive smoke by healthy individuals and those with pre-existing respiratory disease commonly causes acute irritant effects in the upper, and, to a less extent, the lower respiratory tracts. There are sufficient data to indicate that asthmatics suffer significant acute effects following exposure to passive smoke.

Council notes that there is mounting epidemiological evidence that passive smoking may increase the risk of occurrence of lung cancer.