Secondhand Smoke Exposure Linked to Higher Rates of Allergies in ChildrenDec 27, 2007 | Parker Waichman LLP Secondhand smoke exposure is even more dangerous to children than once thought. Although experts have long known that exposure to secondhand smoke either prenatally or early in life can raise a child's risk of developing asthma symptoms, the evidence regarding allergies in general has been mixed, resulting in mixed consensus as to the effects of secondhand smoke on youngsters. Secondhand smoke exposure causes respiratory symptoms in children and slows their lung growth and causes sudden infant death syndrome (SIDS), acute respiratory infections, ear problems, and more frequent and severe asthma attacks in children. But now, a new secondhand smoke study, conducted at the Kaolinska Institute in Stockholm and led by Dr. Eva Lannero suggests that young children who were exposed to cigarette smoke as babies may be more likely to suffer from certain allergies. This new secondhand smoke study suggests that it is possible that being exposed to secondhand smoke triggers inflammation in the lining of young children's airways which may sensitize them to allergy-triggering substances. In the new study, Swedish researchers found that four-year-olds who had been exposed to their parents' cigarette smoking during early infancy were at greater risk of developing allergies to indoor allergens such as dust mites and cat dander. The children studied were also at an increased risk of developing food allergies. Lannero and her colleagues reported the findings in the medical journal Thorax.
The study included more than 4,000 families with infants born between 1994 and 1996. Parents were asked whether either of them smoked when the child was two months, one year, or two years old. At the age of four, the children had their blood tested for antibodies to a range of common allergens, such as cat dander, dust mite, and mold, as well as foods such as milk, eggs, and wheat. The researchers found that children who had been exposed to cigarette smoke at the age of two months were 28 percent more likely to have antibodies to either an indoor air allergen or a food allergen. In particular, their odds of being sensitized to cat dander were double that of children with no secondhand smoke exposure at two months of age. These children were also nearly 50 percent more likely to have antibodies to food allergens. The findings, according to Lannero's team, support the theory that early damage to the mucous membranes lining the airways may make children more sensitive to allergens and offer parents yet another reason to keep their children away from secondhand smoke.
There is no risk-free level of secondhand smoke exposure. Even brief exposure can be dangerous. Secondhand smoke, also known as environmental tobacco smoke, is a complex mixture of gases and particles that include smoke from the burning cigarette, cigar, or pipe tip as well as exhaled smoke and contains at least 250 chemicals known to be toxic, including over 50 that can cause cancer. Exposure causes heart disease and lung cancer in nonsmoking adults; nonsmokers exposed to secondhand smoke increase their heart disease risk by 25–30% and their lung cancer risk by 20–30%. Those with heart disease are at especially high risk.