Second-hand smoke hits genetically susceptible kids harder

December 15, 2005

When U.S. children who possess a variant gene are exposed to second-hand smoke in their homes, they are at a substantially greater risk for developing respiratory illnesses that lead to school absences.

The findings are reported in the second issue of the December 2005 American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.

As part of the California-based Child Health Study, Frank D. Gilliland, M.D., Ph.D., of the Keck School of Medicine at the University of Southern California in Los Angeles, and eight associates analyzed 1,351 fourth grade students attending elementary school in southern California.

The researchers performed DNA analysis of cells from each child's cheek (buccal cells) and examined all participants' school absence reports. They found that genetic susceptibility caused by a variant genotype called "tumor necrosis factor 308A" influences the risk of respiratory-related school absences due to second-hand smoke.

Genotyping showed that 24 percent (324) of the fourth graders possessed one or more copies of the problem-causing variant.

According to baseline questionnaires completed by the children's parents, 20 percent had been exposed to second-hand smoke at home. Of those, 6 percent lived with one or more smokers.

Such exposure rates resulted in a 51 percent greater risk of lower respiratory illness compared with those who were not exposed. The researchers qualify this finding by noting that approximately 15 percent of the children involved in the study had physician-diagnosed asthma, which was associated with a 50 percent increase in risk for illness-related school absences.

The study also found that in children who possessed at least one copy of the tumor necrosis factor variant, exposure to two or more household smokers was associated with a four-fold risk of school absence due to lower respiratory illness, when compared with children who had the same variant, but who were not exposed to second-hand smoke.

The researchers added that second-hand smoke exposure increases the possibility of absence by raising the risk for and the severity of respiratory infection, as well as by increasing asthma-related airflow obstruction, inflammation and other symptoms.

"Adverse respiratory outcomes caused by second-hand smoke exposure include increased occurrence and severity of respiratory symptoms, respiratory infections, physician visits, emergency room visits, hospital admissions and transient changes in lung function," said Dr. Gilliland.

According to the Third National Health and Nutrition Examination Survey, the problem of second-hand smoke exposure in children is a serious one: in the United States, 43 percent of kids between the ages of 4 and 11 years are exposed to second-hand smoke in the home.
Contact: Jon Weiner, USC Health Sciences, Media Relations, 1540 Alcazar Street CHP 236, Los Angeles, California 90033, Phone: (323) 442-2831, E-mail:

American Thoracic Society

Related Children Articles from Brightsurf:

Black and Hispanic children in the US have more severe eczema than white children
A presentation at this year's virtual American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting reveals the disparities that exist for Black and Hispanic children when it comes to Atopic Dermatitis (AD), commonly known as eczema.

Black children with cancer three times less likely to receive proton radiotherapy than White children
A retrospective analysis led by investigators from Brigham and Women's Hospital has found racial disparities in the use of the therapy for patients enrolled in trials.

The Lancet Child & Adolescent Health: First Europe-wide study of children confirms COVID-19 predominately causes mild disease in children and fatalities are very rare
Children with COVID-19 generally experience a mild disease and fatalities are very rare, according to a study of 582 patients from across Europe published today in The Lancet Child & Adolescent Health journal.

Children not immune to coronavirus; new study from pandemic epicenter describes severe COVID-19 response in children
- While most children infected with the novel coronavirus have mild symptoms, a subset requires hospitalization and a small number require intensive care.

How many children is enough?
Most Russians would like to have two children: a boy and a girl.

Preterm children have similar temperament to children who were institutionally deprived
A child's temperament is affected by the early stages of their life.

Only-children more likely to be obese than children with siblings
Families with multiple children tend to make more healthy eating decisions than families with a single child.

Children living in countryside outperform children living in metropolitan area in motor skills
Residential density is related to children's motor skills, engagement in outdoor play and organised sports. that Finnish children living in the countryside spent more time outdoors and had better motor skills than their age peers in the metropolitan area.

Hispanic and black children more likely to miss school due to eczema than white children
In a study that highlights racial disparities in the everyday impact of eczema, new research shows Hispanic and black children are more likely than white children to miss school due to the chronic skin disease.

Children, their parents, and health professionals often underestimate children's higher weight status
More than half of parents underestimated their children's classification as overweight or obese -- children themselves and health professionals also share this misperception, according to new research being presented at this year's European Congress on Obesity (ECO) in Glasgow, UK (April 28-May 1).

Read More: Children News and Children Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to