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Environmental Factor, May 2012

Early-life exposure to secondhand smoke affects girls more than boys

By Amanda Harper

Kelly Brunst

Kelly Brunst was first author on the study, which underscores the importance of exposures during critical windows of development and adds support to the two-hit hypothesis about host susceptibility. (Photo courtesy of UCSF)

Grace LeMasters, Ph.D.

Veteran grantee LeMasters is also a member of the National Advisory Environmental Health Sciences Council, which meets three times each year at NIEHS. (Photo courtesy of UCSF)

The negative health effects of early-life exposure to secondhand smoke appear to impact girls more than boys — particularly those with early-life allergic sensitization, according to new NIEHS-funded research (http://www.ncbi.nlm.nih.gov/pubmed/22435840)  from the University of Cincinnati (UC) College of Medicine.

Epidemiologists with UC’s Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS), (http://www.eh.uc.edu/ccaaps/Default_x.html)  funded by NIEHS, found that children exposed to high levels of secondhand smoke who also had allergic sensitizations during early childhood are at greater risk for decreased lung function at age 7 compared to children who had not developed allergic sensitizations by this age.

Additionally, lung function among girls was six times worse than in boys who were exposed to similar levels of both secondhand smoke and allergen sensitization.

Timing is crucial

“Our study shows that the timing of allergic sensitization is crucial because children who are sensitized by age 2 are more likely to suffer the greatest lung deficits during childhood as a result of secondhand smoke exposure,” explained Kelly Brunst, first author of the paper and a doctoral candidate in UC’s division of epidemiology and biostatistics. “This association was not observed at age 4 or 7, emphasizing the importance of this critical window for lung development.”

The team’s findings were published online March 21 in the journal Pediatric Allergy and Immunology.

This is the first study to explore the differential gender effects of secondhand smoke exposure using an internal biomarker for secondhand smoke — hair cotinine, a product of nicotine metabolism — while also accounting for the importance of timing and extent of allergic sensitization on lung function.

Previous studies have estimated that one in four children in the United States living in a home with at least one smoker have cotinine concentrations more than twice as high as those living with nonsmoking adults. Secondhand smoke exposure during childhood has also been associated with respiratory illness, decreased lung function, and asthma development or exacerbation.

A role for gender

“Our results provide valuable information regarding the interwoven relationships between early-life exposure to secondhand tobacco smoke, allergic sensitization, gender, and lung function,” said Grace LeMasters, Ph.D., (http://www.eh.uc.edu/dir_individual_details.asp?qcontactid=35)  UC professor of environmental health and principal investigator of CCAAPS.

“It’s likely that the complex interaction between secondhand smoke and pulmonary function loss in boys and girls is ultimately dependent on the timing of exposure as well as the child’s total load in relationship to cumulative risk factors — exposures, allergic sensitization, asthma status, genetic susceptibility, and sex hormones.”

CCAAPS is a long-term childhood study examining the effects of environmental exposures on respiratory health and allergy development. All infants in the study had at least one parent with known allergies and were followed from infancy until age 7.

For this study, researchers examined a population of 476 children in the Greater Cincinnati metropolitan area identified from birth to be at increased risk for allergies based on family history and proximity to major roads. Hair samples were collected at age 2 and 4 to measure average cotinine concentrations. At age 7, all children had lung function and asthma diagnosis testing. This information was then correlated with data about allergy sensitization collected through annual skin prick allergy testing, self-report questionnaires about allergy symptoms, and the home and school environment.

Collaborators in the study include UC’s Linda Levin, David Bernstein, M.D., James Lockey, M.D., Manuel Villareal, M.D., Jeff Burkle, and Roy McKay, as well as Gurjit Khurana Hershey, M.D., Patrick Ryan, M.D., and Jocelyn Biagini Meyers, Ph.D., of Cincinnati Children’s Hospital Medical Center. Sherry Evans of the Bernstein Clinical Research Center also contributed to this study.

Citation: Brunst KJ, Ryan PH, Lockey JE, Bernstein DI, McKay RT, Khurana Hershey GK, Villareal M, Biagini Myers JM, Levin L, Burkle J, Evans S, LeMasters GK. (http://www.ncbi.nlm.nih.gov/pubmed/22435840)  2012. Unraveling the relationship between aeroallergen sensitization, gender, second-hand smoke exposure, and impaired lung function. Pediatr Allergy Immunol; doi: 10.1111/j.1399-3038.2012.01292.x [Online 21 March 2012].

(Amanda Harper is a public information officer in the Office of Public Relations and Communications at the UC Academic Health Center. For more information about this study, contact Harper by phone at 513-558-4657 or by email at amanda.harper@uc.edu .)




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