"Long before it's in the papers"
September 24, 2012

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Common chemical linked to nearly tripled odds of youth obesity

Sept. 18, 2012
Courtesy of JAMA and Archives Journals
and World Science staff

Young peo­ple heavily ex­posed to a very com­mon in­dus­t­ri­al chem­i­cal known as BPA may have 2.6 times the odds of be­com­ing obese as those with low ex­po­sure, new re­search sug­gests.

The study is based on what re­search­ers called a na­t­ionally rep­re­sent­a­tive sam­ple of nearly 3,000 U.S. chil­dren aged six through 19. Sci­en­tists meas­ured uri­nary lev­els of the chem­i­cal, whose full name is bisphe­nol A and is com­monly found in food pack­ag­ing.

“To our knowl­edge, this is the first re­port of an as­socia­t­ion of an en­vi­ron­men­tal chem­i­cal ex­po­sure with child­hood obes­ity in a na­t­ionally rep­re­sent­a­tive sam­ple,” the re­search­ers wrote, de­tail­ing their find­ings in the Sept. 19 is­sue of the Jour­nal of the Amer­i­can Med­i­cal As­socia­t­ion.

BPA ex­po­sure is so com­mon that an es­ti­mat­ed 92.6 of peo­ple over age five have de­tect­a­ble lev­els in their urine, said Leonardo Trasande of the New York Uni­vers­ity School of Med­i­cine, one of the in­ves­ti­ga­tors. He added that it usu­ally en­ters our bod­ies in our food and that it has been found to dis­rupt the me­tab­o­lism, pos­sibly ac­count­ing for its ef­fect on body weight.

Trasande and col­leagues examined data on 2,838 youths, ran­domly se­lected for meas­ure­ment of uri­nary BPA con­centra­t­ion ac­cord­ing to sur­veys con­ducted from 2003 to 2008 called the Na­t­ional Health and Nu­tri­tion Ex­amina­t­ion Sur­veys.

Par­ti­ci­pants in the top one-fourth for uri­nary BPA had a 2.6 high­er odds of obes­ity than par­ti­ci­pants in the bot­tom fourth, the study found. Par­ti­ci­pants in the second-highest fourth had about twice the odds of obes­ity as those in the bot­tom fourth. The sci­en­tists said they con­trolled for many oth­er obes­ity risk fac­tors in­clud­ing race and eth­ni­city, age, care­giver educa­t­ion, po­verty to in­come ra­tio, sex, ca­lor­ic in­take and tel­e­vi­sion watch­ing.

The re­search­ers al­so found that obes­ity was­n’t as­sociated with ex­po­sure to oth­er chem­i­cals re­lat­ed to BPA, called phe­nols and com­monly used in oth­er con­sum­er prod­ucts, such as sun­screens and soaps.

Health ad­vo­cates and pol­i­cy­makers have long been con­cerned about BPA, the in­ves­ti­ga­tors added. A Na­t­ional In­sti­tutes of Health web­page pro­vides in­forma­t­ion on BPA in­clud­ing sug­ges­tions for those who want to re­duce their ex­po­sure.

“We note the re­cent FDA ban of BPA in ba­by bot­tles and sippy cups, yet our find­ings raise ques­tions about ex­po­sure to BPA in con­sum­er prod­ucts used by old­er chil­dren,” Trasande and col­leagues wrote in their re­port. 

“Last year, the FDA de­clined to ban BPA in alu­mi­num cans and oth­er food pack­ag­ing, an­nounc­ing ‘rea­son­able steps to re­duce hu­man ex­po­sure to BPA in the hu­man food sup­ply’ and not­ing that it will con­tin­ue to con­sid­er ev­i­dence on the safe­ty of the chem­i­cal. Care­fully con­ducted lon­gi­tu­di­nal stud­ies that as­sess the as­socia­t­ions iden­ti­fied here will yield ev­i­dence many years in the fu­ture.”

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Young people heavily exposed to a very common industrial chemical known as BPA may have 2.6 times the odds of becoming obese as those with low exposure, new research suggests. The study is based on what researchers called a nationally representative sample of nearly 3,000 U.S. children aged six through 19. Scientists measured urinary levels of the chemical, whose full name is bisphenol A and is commonly found in food packaging. “To our knowledge, this is the first report of an association of an environmental chemical exposure with childhood obesity in a nationally representative sample,” the researchers wrote, detailing their findings in the Sept. 19 issue of the Journal of the American Medical Association. BPA exposure is so common that an estimated 92.6 of people over age five have detectable levels in their urine, said Leonardo Trasande of the New York University School of Medicine, one of the investigators. He added that it usually enters our bodies in our food and that it has been found to disrupt the metabolism, possibly accounting for its effect on body weight. Trasande and colleagues studied what they called a nationally representative sample of 2,838 youths, randomly selected for measurement of urinary BPA concentration according to surveys conducted from 2003 to 2008 called the National Health and Nutrition Examination Surveys. Participants in the top “quartile,” or top 25 percent, for urinary BPA had a 2.6 higher odds of obesity than participants in the bottom quartile, the study found. Participants in the second-highest quartile had about twice the odds of obesity as those in the bottom quartile. The scientists said they controlled for many other obesity risk factors including race and ethnicity, age, caregiver education, poverty to income ratio, sex, caloric intake and television watching. The researchers also found that obesity wasn’t associated with exposure to other chemicals related to BPA, called phenols and commonly used in other consumer products, such as sunscreens and soaps. Health advocates and policy makers have long been concerned about BPA, the investigators added. A National Institutes of Health webpage provides information on BPA including suggestions for those who want to reduce their exposure. “We note the recent FDA ban of BPA in baby bottles and sippy cups, yet our findings raise questions about exposure to BPA in consumer products used by older children,” Trasande and colleagues wrote in their report. “Last year, the FDA declined to ban BPA in aluminum cans and other food packaging, announcing ‘reasonable steps to reduce human exposure to BPA in the human food supply’ and noting that it will continue to consider evidence on the safety of the chemical. Carefully conducted longitudinal studies that assess the associations identified here will yield evidence many years in the future.”