Urinary Biomarkers for Phthalates Associated with Asthma in Norwegian Children

Randi J. Bertelsen,^1,2 Karin C. Lødrup Carlsen,^3,4 Antonia M. Calafat,⁵ Jane A. Hoppin,² Geir Håland,^3,4 Petter Mowinckel,³ Kai-Håkon Carlsen,^3,4 and Martinus Løvik¹


¹Department of Food, Water and Cosmetics, Norwegian Institute of Public Health, Oslo, Norway; ²Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, USA; ³Department of Pediatrics, Oslo University Hospital, Oslo, Norway; ⁴Faculty of Medicine, University of Oslo, Oslo, Norway; ⁵National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA


Abstract

Background: High-molecular-weight phthalates in indoor dust have been associated with asthma in children, but few studies have evaluated phthalate biomarkers in association with respiratory outcomes.


Objectives: We explored the association between urinary concentrations of phthalate metabolites and current asthma.


Methods: In a cross-sectional analysis, 11 metabolites of 8 phthalates [including four metabolites of di(2-ethylhexyl) phthalate] were measured in one first morning void collected from 2001 through 2004 from 623 10-year-old Norwegian children. Logistic regression models controlling for urine specific gravity, sex, parental asthma, and income were used to estimate associations between current asthma and phthalate metabolite concentrations by quartiles or as log₁₀-transformed variables.


Results: Current asthma was associated with both mono(carboxyoctyl) phthalate (MCOP) and mono(carboxynonyl) phthalate (MCNP), although the association was limited to those in the highest quartile of these chemicals. The adjusted odds ratio (aOR) for current asthma was 1.9 (95% CI: 1.0, 3.3) for the highest MCOP quartile compared with the lowest quartile, and 1.3 (95% CI: 0.98, 1.7) for an interquartile-range increase. The aOR for current asthma was 2.2 (95% CI: 1.2, 4.0) for the highest MCNP quartile and 1.3 (95% CI: 1.0, 1.7) for an interquartile-range increase. The other phthalate metabolites were not associated with current asthma.


Conclusions: Current asthma was associated with the highest quartiles of MCOP and MCNP, metabolites of two high molecular weight phthalates, diisononyl phthalate and diisodecyl phthalate, respectively. Given the short biological half-life of the phthalates and the cross-sectional design, our findings should be interpreted cautiously.


Key words: asthma, biomarkers, children, endocrine disruptors, phthalates. 


Environ Health Perspect 121:251–256 (2013). http://dx.doi.org/10.1289/ehp.1205256 [Online 16 November 2012]


Address correspondence to R.J. Bertelsen, Department of Food, Water and Cosmetics, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway. Telephone: 47 21076327. E-mail: randi.jacobsen.bertelsen@fhi.no


Supplemental Material is available online (http://dx.doi.org/10.1289/ehp.1205256).


We thank M.C. Munthe-Kaas, C.S. Devulapalli, and S. Knutsen at Oslo University Hospital for their assistance with data collection, and A. Grestad, B. Hasseltvedt, E.-C. Groeng, Å. Eikeset, and B. Stensby at the Norwegian Institute of Public Health. We acknowledge M. Silva, E. Samandar, J. Preau, and T. Jia (Centers for Disease Control and Prevention) for measuring the phthalate metabolites. 


The study was funded by the Norwegian Institute of Public Health, Research Council of Norway, and Oslo University Hospital, and supported in part by the Intramural Research Program of the National Institutes of Health (NIH), National Institute of Environmental Health Sciences (NIEHS). An unrestricted grant from the AstraZeneca Norway fund for research within pulmonology was given in 2006 to G.H. for the cost of phthalate analyses in urine. The sponsor had no influence on the analyses, interpretation, or presentation. The study was performed within ORAACLE (the Oslo Research Group of Asthma and Allergy in Childhood: the Lung and Environment), a member of GA2LEN (Global Allergy and Asthma European Network), supported by the Sixth EU Framework program for research, contract FOOD-CT-2004-506378. 


The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the CDC.


The authors declare they have no actual or potential competing financial interests.


Received 25 March 2012; Accepted 15 November 2012; Online 16 November 2012.