Grantee Research Project Results

Infant Inhalation Exposure to Indoor Air Pollutants while Sleeping and Crawling

EPA Grant Number: F13D10740
Title: Infant Inhalation Exposure to Indoor Air Pollutants while Sleeping and Crawling
Investigators: Boor, Brandon Emil
Institution: The University of Texas at Austin
EPA Project Officer: Lee, Sonja
Project Period: August 1, 2014 through August 1, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Fellowship - Environmental Science , Academic Fellowships

Objective:

The objectives of the proposed research are to (1) evaluate crib mattresses as a source of volatile organic compounds (VOCs) and plasticizers and identify the unique attributes of human exposure in the sleep microenvironment; (2) develop a full-scale crawling robot that can simulate the locomotion of a crawling infant to investigate the mechanisms of crawling-induced resuspension of settled floor dust particles; and (3) evaluate near-floor infant exposure to airborne particles.

Approach:

This first phase of this work will evaluate the emissions of VOCs from a collection of 20 new and used infant crib mattresses and identify phthalate and alternative plasticizers in crib mattress covers. Chamber experiments will determine VOC area-specific emission rates under different thermal conditions, as well as breathing zone concentrations. Material-phase concentrations of plasticizers will be determined through solvent extractions and analysis via gas chromatography-mass spectrometry. Target plasticizers include bis (2-ethylhexyl) phthalate (DEHP); bis (2-ethylhexyl) isophthalate (iso-DEHP); diisononyl phthalate (DINP); diisononyl cyclohexane-1,2-dicarboxylate (DINCH); and di (2-ethylhexyl) adipate (DEHA). A literature review will identify the unique attributes of exposure to pollutants in infant and adult sleep microenvironments and provide a comprehensive overview of pollutants found in mattresses and mattress dust. The second phase of this research involves designing and constructing a full-scale (~ 8 kg) crawling robot that can simulate the locomotion of a crawling infant. Microcontrollers will control servo motors and actuators will drive each limb. The robot will simulate two common crawling techniques: a belly crawl and a hands-andknees crawl. An optical particle sizer will be mounted on the top of the robot for mobile sampling of breathing-zone particle concentrations (300 nm to 10 µm). Full-scale experiments will be conducted in a large environmental chamber. Particle resuspension will be quantified through the resuspension rate metric, and exposure will be quantified through the intake fraction metric. The effect of flooring type (carpeted vs. hard flooring), dust loading (1–10 g/m²), particle size and crawling motion will be evaluated. In thehe third phase the crawling robot will be deployed in different indoor environments for field measurements of near-floor particle concentrations. In addition to mobile monitoring of resuspended fine and coarse particles, ultrafine particles also will be measured with a scanning mobility particle size.

Expected Results:

This research will help to characterize infant crib mattresses as a source of VOCs and plasticizers in the sleep microenvironment. The crawling robot will be used to determine size-resolved particle resuspension rates, breathing- zone concentrations and intake fractions in both controlled chamber experiments and field measurements. The breathing-zone concentrations will be used to model an infant’s daily inhalation dose of particles while engaged in near-floor activities and the fraction of particles that deposit in various regions of the lung.

Potential to Further Environmental/Human Health Protection

The infant sleep microenvironment is a critically important, yet understudied, indoor space. This research will help to better understand how crib mattresses contribute to an infant’s cumulative exposure to various chemicals and the health consequences of this particular product. Some phthalate plasticizers are endocrine-disrupting compounds, and repeated and prolonged infant exposure while sleeping (through inhalation and dermal contact with the mattress cover) is of particular concern. Furthermore, little is known about the process by which infants stir up settled dust particles as they engage in near-floor activities. This research will help determine how crawling-induced resuspension contributes to an infant’s daily exposure to fine and coarse particles. The crawling robotic sampling platform developed in this research also will serve as a useful tool for future work on characterizing the fungal and bacterial composition of resuspended dust particles.

Supplemental Keywords:

indoor air quality, particle resuspension, sleep microenvironment

Progress and Final Reports:

2015

Final