Effects of secondhand smoke in children

Children exposed to secondhand cigarette smoke in early infancy are more likely to suffer certain allergies than those who had not been so exposed. Passive smoking has been associated with lung cancer and heart disease and is the main reason for smoking bans in workplaces and indoor public places, including restaurants, bars and nightclubs. But when children are exposed to passive smoking, it has all the more negative consequences. Experts have known that exposure to secondhand smoke either before birth or early in life can raise a child's risk of developing asthma symptoms. But the evidence regarding allergies in general has been mixed. To study the association of secondhand smoke with allergy in children, researchers from the Karolinska Institute in Stockholm studied more than 4,000 families with infants born between 1994 and 1996. Parents were asked about their smoking habits when the child was two months, one year or two years old. At the age of four years, the children had their blood tested for antibodies to a range of common allergens, such as cat dander, dust mites and mold, as well as foods such as milk, eggs and wheat. It was found that children who had been exposed to cigarette smoke at the age of two months were 28 per cent more likely to have antibodies to either an indoor air allergen or a food allergen. In particular, their odds of being sensitised to cat dander (hair and dead skin) were double that of children with no secondhand smoke exposure at two months of age. And they were nearly 50 per cent more likely to have antibodies to food allergens. This could be because secondhand smoke triggers inflammation in the lining of young children's airways, which may sensitise them to allergy-triggering substances. The findings support the theory that early damage to the mucous membranes lining the airways may make children more sensitive to allergens. The results also offer parents yet another reason to keep their children away from secondhand smoke.