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In the U.S., phthalates are rarely listed as ingredients on products in which they are used. No steps have been taken to protect the developing fetus by alerting pregnant women to potential exposures.

Phthalates heighten risk for childhood asthma

Children born to pregnant women exposed to high levels of household chemicals — butylbenzyl phthalate and di-n-butyl phthalate (pronounced THAL-ates) — had more than a 70 percent increase in asthma.

Phthalates are used in everything from synthetic fragrances to plastic food containers, vinyl flooring, insect repellent, shower curtains, even steering wheels and dashboards ( that "new car smell" contains phthalates).

Since 2009, several phthalates — including butylbenzyl phthalate (BBzP) and di-n-butyl phthalate (DnBP) —have been banned from children's toys and other childcare articles in the United States. However, no steps have been taken to protect the developing fetus by alerting pregnant women to potential exposures.

Only two phthalates studied—di-2-ethylhexyl phthalate (DEHP) and diethyl phthalate (DEP)—were not associated with a diagnosis of asthma or asthma-like symptoms. Other asthma risk factors include tobacco smoke, air pollution, obesity, and a history of allergies. But phthalates are subtlely insinuated into plastic children's toys, plastic bottles containing household cleansers, water and soft drink bottles all without notification on container labels, that more attention must be paid by pregnant women to avoid this chemical exposure.

In the U.S., phthalates are rarely listed as ingredients on products in which they are used.

The current findings build on the team's 2012 studies on the same cohort study of mothers and children and reporting that children exposed to DEP or BBzP had elevated risk of asthma-related airway inflammation and prenatal exposure to BBzP was associated with elevated risk of childhood eczema. In 2013, the researchers reported that early childhood exposure to bisphenol A (BPA) also was associated with risk for asthma.

"The fetus is extremely vulnerable during pregnancy. While it is incumbent on mothers to do everything they can to protect their child, they are virtually helpless when it comes to phthalates like BBzP and DnBP that are unavoidable. If we want to protect children, we have to protect pregnant women."

Rachel Miller MD, professor of Medicine (Pediatrics) and Environmental Health Sciences, chief of Pediatric Allergy, Immunology, and Rheumatology at Columbia University Medical Center, co-deputy director the Columbia Center for Children's Environmental Health at Columbia's Mailman School of Public Health, and study senior author.

More recently, research found that risk from BPA exposure during childhood increased substantially if mothers also had high BBzP  exposure during pregnancy (results were published August, 2014 in the Journal of Allergy and Clinical Immunology).

"Everyone from parents to policymakers is concerned by the steep rise in the number of children who develop asthma. Our goal is to try and uncover causes of this epidemic so we can better protect young children from this debilitating condition. Our study presents evidence that these two phthalates are among a range of known risk factors for asthma,"

Robin Whyatt DrPH, professor of Environmental Health Sciences, co-deputy director, Columbia Center for Children's Environmental Health at the Mailman School, and first author.

All but one of the urinary samples from mothers and children contained metabolites for all four phthalates. Samples had a wide range of concentrations—from undetected to 550 ng/ml for the BBzP metabolites and from 1 to 1,110 ng/mL for DnBP metabolites. It is unclear what behaviors or which products contributed to greater exposures.

Researchers followed 300 pregnant women and their children enrolled in the Center's longitudinal cohort study in New York City.

Levels of exposure to four suspect phthalates were measured through urine samples. Samples were collected from mothers during the third trimester and in children at ages 3, 5, and 7. Chemical analysis was conducted by the Centers for Disease Control and Prevention. Researchers compared asthma risk in children between 5 and 11 years old and born to mothers with concentrations of phthalates in the upper third versus the lower third.

Almost a third of the children (94) developed physician-diagnosed asthma. Another 60 children had a history of wheeze and other asthma-like symptoms without a diagnosis of asthma. In this group too, the researchers found a link between prenatal exposure to DnBP and the symptoms.

For now, it's not known how phthalates increase risk for asthma. Studies of prenatal exposure to BBzP hint that inflammation and oxidative stress may play a role.

Abstract
Background: Studies suggest that phthalate exposures may adversely affect child respiratory health.

Objectives: Evaluate associations between asthma diagnosed between child ages 5-11 years and prenatal exposures to butylbenzyl phthalate (BBzP), di-n-butyl phthalate (DnBP), di-2-ethylhexyl phthalate (DEHP) and diethyl phthalate (DEP).

Methods: Phthalate metabolites were measured in spot urine collected from n=300 pregnant inner-city women. Children were examined by an allergist or pulmonologist based on the first parental report of wheeze, other respiratory symptoms, and/or use of asthma rescue/controller medication in the last 12 months on repeat follow-up questionnaires. Standardized diagnostic criteria were used to classify these children as either having or not having current asthma at the time of the physician examination. Children without any report of wheeze or the other asthma-like symptoms were classified as non-asthmatics at the time of the last negative questionnaire. Modified poisson regression analyses were used to estimate relative risks (RR) controlling for specific gravity and potential confounders.

Results: 154/300 (51%) children were examined by a physician because of reports of wheeze, other asthma-like symptoms and/or medication use; n=94 were diagnosed with current asthma and n=60 without current asthma. The remaining n=146 children were classified as non-asthmatic. Compared to non-asthmatics, prenatal metabolites of BBzP and DnBP were associated with a history the asthma-like symptoms (p<0.05) and with the diagnosis of current asthma: RR 1.17 (95% CI: 1.01, 1.35) and RR 1.25 (95% C I 1.04, 1.51) per natural log-unit increase, respectively. Risk of current asthma was > 70% higher among children with maternal prenatal BBzP and DnBP metabolite concentrations in the 3rd versus 1st tertile.

Conclusion: Prenatal exposure to BBzP and DnBP may increase the risk of asthma among inner-city children. However, as this is the first such finding, results require replication.

Co-authors include Columbia Center for Children's Environmental Health director Frederica Perera, Matthew Perzanowski, Andrew Rundle, and Lori Hoepner—all of Columbia's Mailman School; Kathleen Donohue of Columbia University Medical Center; Allan Just of the Harvard School of Public Health; and Antonia Calafat of the Centers for Disease Control and Prevention.

The research was supported by grants from the National Institute of Environmental Health Sciences (NIEHS) (R01ES014393, R01ES13163) and NIEHS/U.S. Environmental Protection Agency (P01 ES09600/RD 83214101, P30ES009089). The researchers declare no competing financial interests.

About Columbia University's Mailman School of Public Health
Founded in 1922, Columbia University's Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Mailman School is the third largest recipient of NIH grants among schools of public health. Its over 450 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change & health, and public health preparedness. It is a leader in public health education with over 1,300 graduate students from more than 40 nations pursuing a variety of master's and doctoral degree programs. The Mailman School is also home to numerous world-renowned research centers including ICAP (formerly the International Center for AIDS Care and Treatment Programs) and the Center for Infection and Immunity. For more information, please visit http://www.mailman.columbia.edu.

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