Assessing Inhalation Exposure to Aerosolized Contaminants from Drinking Water

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

1605355 Dietrich This proposed project fills a critical knowledge gap concerning human exposure, at the air-water-human interface, to contaminants from aerosols emitted by ultrasonic humidifiers. Typically, consumers purchase ultrasonic humidifiers, fill them with drinking water, and use them in confined spaces such as bedrooms for several hours per day. The resulting inhalation exposure information, from ultrasonic humidifiers, will allow scientists to reasonably assess the human health risks associated with dissolved contaminants in drinking water and subsequently offer recommendations for consumer use. The fundamental characterization of ultrasonic humidifier aerosol composition, fate and transport under realistic living conditions, and propensity for infant, child, and adult inhalation exposure and resulting inhaled dose, will be the first of its kind for assessing this aspect of the air-water-human interface. The description of the relationships between aerosol size - contaminant concentration and aerosol deposition patterns on room surfaces will provide new data and perspective for the health effects of aerosols. This project has implications for human health because of the uncertainty surrounding inhalation exposures from aerosolized drinking water. The experimental research has four objectives and the reseach is guided by four hypotheses: 1) To use particle size and cascade impactor instruments, in conjunction with inductively coupled plasma mass spectrometry, to comprehensively characterize humidifier aerosols in size, distribution, and inorganic chemical composition for varying water qualities representative of realistic drinking waters. Hypothesis 1: Inorganic contaminant concentrations are the same in all aerosol particle sizes for a given water quality. 2) To examine aerosol deposition on surfaces is determined as a function of distance from a humidifier which is situated in realistic indoor living scenario. Sampling locations are both within and outside the humidifier plume. Hypothesis 2: Inorganic contaminant concentrations will be deposited at similar aerial concentrations in all locations of the room. 3) The experimental data are inputs to calibrate and validate the USEPA RISK Indoor Air Quality model for its first application to room-sized ultrasonic humidifiers. Hypothesis 3: The USEPA RISK model can be calibrated to meet ASTM air modeling guidelines (1991) using the experimental data from this study. 4) The data obtained will use the USEPA RISK model to assess the human inhalation exposure to aerosolized contaminants for many realistic exposure scenarios involving infants, children, and adults. Hypothesis 4: The indoor air model confirms that human inhalation exposure to inorganic contaminants in ultrasonic humidifier aerosols exceed health guidelines. The model results will be evaluated with respect to inhalation exposure regulations, existing dose data, and geographically varying water quality. The PI and co-PIs are committed to developing the professional, ethical, outreach, and research preparation of students on this project. The PhD and undergraduate students will be actively recruited from underrepresented groups, as has been done for many years by the faculty involved in this project. This project will recruit underrepresented students and provide them educational, research, and professional experiences, including mentoring grade 6-12 students. The student researchers will communicate their results throughout the globe through blogs at the Water INTERface website (https://blogs.lt.vt.edu/water/), maintained by the Virginia Tech Graduate School for faculty and students in water research and though publication of scientific articles.