Phthalates and Childhood Asthma: Revealing an Association through Urinary Biomarkers
Tanya Tillett, MA, of Durham, NC, is a staff writer/editor for EHP. She has been on the EHP staff since 2000 and has represented the journal at national and international conferences.
Exposure to phthalates, substances used as plasticizers in a large number of consumer goods, can occur by ingestion, inhalation, or skin contact. Children—who are uniquely vulnerable to adverse health effects of environmental exposures because of their still-developing neurological, immunological, and respiratory systems—can receive particularly high exposures due to more frequent hand-to-mouth activity, combined with contact with polyvinyl chloride (PVC) surfaces and house dust, which collects phthalates (and other chemicals). Researchers now report an association between phthalate exposure and asthma and allergic disease in a cohort of 10-year-old Norwegian children [EHP 121(2):251–256; Bertelsen et al.].
The research team conducted a cross-sectional analysis of urine sample data from 623 children participating in the 10-year followup to the prospective Environment and Childhood Asthma study in Oslo. The followup included structured interviews with parents and blood tests, lung function tests, clinical examinations, and skin prick tests for allergic sensitization for children. Samples of first-morning urine were collected and assessed for three metabolites of low-molecular-weight phthalates (commonly used in personal care products) and eight metabolites of high-molecular-weight phthalates (commonly used in PVC applications such as flooring, electrical cords, car interiors, and older toys). The investigators used logistic regression modeling to estimate associations between current asthma and phthalate metabolite concentrations.
Previous animal studies have shown an association between high-molecular-weight phthalates and allergic disease development, while epidemiological studies have shown exposure to house dust containing several of these chemicals to be associated with asthma and allergic disease. The current analysis revealed an association between asthma in children and the highest quartiles of exposure to the metabolites mono-carboxyoctyl phthalate and mono-carboxynonyl phthalate. The parent compounds of these metabolites are high-molecular-weight phthalates used primarily as plasticizers in PVC items. No association was observed between asthma and the nine other metabolites, nor was any association detected between any metabolites and allergic sensitization.
Limitations of the study include the cross-sectional design and measurements based on single urine samples, which do not reflect phthalate exposures over time. However, the findings do support the growing body of evidence showing an association between asthma and exposure to high-molecular-weight phthalates.
The February 2013 News article “Phthalates and Childhood Asthma: Revealing an Association through Urinary Biomarkers” [Environ Health Perspect 121:A59 (2013)] referred to plastic/polyvinyl chloride toys as “phthalate-rich” in a discussion of phthalate exposures among 10-year-old Norwegian children. The Consumer Product Safety Improvement Act of 2008 and European Commission Decision C(1999) 4436 of 7 December 1999 eliminated or suspended the use of certain phthalates of concern in toys and children’s products. The children discussed in the News article were assessed in 2001–2004 and may have had access to toys purchased before the 1999 European ban. However, it was incorrect to suggest that all plastic toys continue to be “rich” sources of phthalates, and the article has been revised accordingly.
EHP regrets the error.
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CEHN March 2015 Article of the Month
“Maternal Arsenic Exposure, Arsenic Methylation Efficiency, and Birth Outcomes in the Biomarkers of Exposure to ARsenic (BEAR) Pregnancy Cohort in Mexico” (Environ Health Perspect; DOI:10.1289/ehp.1307476) has been selected by the Children’s Environmental Health Network (CEHN) as its March 2015 Article of the Month. These CEHN summaries discuss the potential policy implications of current children’s environmental health research.
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