Crib Mattresses May Emit Phthalates

Ying Xu Assistant Professor, Ph.D. Department of Civil, Architectural and Environmental Engineering University of Texas, Interview with:
Ying Xu
Assistant Professor, Ph.D.
Department of Civil, Architectural and Environmental Engineering
University of Texas, Austin

Medical Research: What is the background for this study? What are the main findings?

Response: Phthalates have been widely used as plasticizers to enhance the flexibility of polyvinyl chloride (PVC) products.  They are ubiquitous and persistent indoor pollutants and may result in profound and irreversible changes in the development of human reproductive tract.

In this study, we found that the emissions of phthalates and phthalate alternatives increase significantly with increasing temperature.  We developed an emission model and validated the model via chamber experiments.  Further analysis showed that, in infant sleep microenvironments, an increase in the temperature of mattress can cause a significant increase in emission of phthalates from the mattress cover and make the concentration in breathing zone about four times higher than that in the room, resulting in potentially high exposure.  In residential homes, an increase in the temperature from 25 to 35 ºC can elevate the gas-phase concentration of phthalates by more than a factor of 10, but the total airborne concentration may not increase that much for less volatile compounds.

Medical Research: What should clinicians and patients take away from your report?

Response: The most important take home messages from this study is that phthalates or their alternatives can be emitted from PVC consumer products and building materials. Increase of temperature may enhance the emission significantly.  The sleep microenvironment and its role in infant health deserves much more attention. Parents should be careful in selection of crib mattresses to reduce their children’s exposure to phthalates from the mattress covers.

Medical Research: What recommendations do you have for future research as a result of this study?

Response: Although simulation using the two-zone model is a first-of-a-kind study of sleep microenvironments, it still served only as a screening-level analysis.  We recognize that there are several limitations associated with the current model simulation.  However, since infants spend most of their time sleeping with their breathing zone and skin in immediate proximity to the source, they are likely to be exposed to a significant amount of phthalates through inhalation of air (gas and particles), dermal transfer as a result of contact with the source, and direct air-to-skin uptake.  Therefore, systematic chamber studies should be conducted and theoretical models should be developed to improve our understanding of the fate and transport of phthalates as well as other semi-volatile organic compounds (e.g., flame retardants emitted from mattresses) in infants’ sleep microenvironments.  These developments represent the essential first step in allowing the accurate evaluation of infant exposures, better investigation of subsequent health effects, and improved strategies to limit exposures.


Emission of Phthalates and Phthalate Alternatives from Vinyl Flooring and Crib Mattress Covers: The Influence of Temperature

Yirui Liang and Ying Xu *

Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712-1094, United States
Environ. Sci. Technol., 2014, 48 (24), pp 14228–14237
DOI: 10.1021/es504801x
Publication Date (Web): November 24, 2014

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Last Updated on December 21, 2014 by Marie Benz MD FAAD