2013 Spring Meeting Abstracts


Computational modeling of the toxicodynamic effects in the respiratory system of mice due to nanoparticle inhalation
Dwaipayan Mukherjee, Steven G. Royce, Danielle Botelho, Andrew J. Gow, Panos G. Georgopoulos

Background: Nanoparticles are ubiquitous in the ambient air and might be produced as a result of industrial processes or might be a part of household consumer products as Engineered Nanomaterials (ENMs). Inhaled fine and ultrafine particles are arrested at various stages of the respiratory system. These ultrafine or nano-sized particles cause various toxicodynamic changes in the respiratory system in humans. Aim: The aim of this work is to develop a multiscale computational model for the physiologically based simulation of toxicokinetic and toxicodynamic processes associated with nanoscale particle inhalation. The model developed for mice will be ultimately extrapolated to humans. Methods: The model deals with pulmonary tissue with explicit focus on the cells and surfactant chemicals which regulate the process of breathing and respond to xenobiotics. The respiratory system processes are decomposed into four functional modules with alveolar surfactant dynamics, cellular dynamics, cellular inflammation and nanoparticle-surfactant interaction being considered separately. Pulmonary Type I and Type II cells, alveolar macrophages, and inflammatory cells were included in the model along with surfactant phospholipids, and surfactant proteins. The model also considers the mechanistic pathways involved in cellular inflammatory processes leading to changes in the levels of cytokines and cell counts in the lung. Results and discussion: The model was coded and the results compared with in-vivo measurements in mice on lung function response and lung lavage analysis following exposures to different types of nanomaterials.

Regional modeling for the Ozone Transport Commission (OTC) to support development of attainment strategies
Xiaogang Tang, Michael Ku, Winston Hao, Eric Zalewsky, Kevin Civerolo, Jin-Sheng Lin, Shan He, Tonalee Key, Panos Georgopoulos

The community multiscale air quality model (CMAQ), developed by USEPA, is used to simulate photochemical air pollution in the Northeast US for two scenarios involving past (2007) and projected future (2020) conditions. For the 2007 “base” case CMAQ inputs include 2007 emission inventories and 2007 meteorological data. For the 2020 “proxy” case, adjustment factors are applied to 2007 emissions and meteorological data are the same as for year 2007. Performance evaluation of the OTC 2007 CMAQ “Level 3” 12-km base case is presented here. CMAQ performed well in capturing the observed diurnal and temporal patterns with less error in daytime than in nighttime, which may be due to excessive vertical mixing in the nighttime.CMAQ performed better with rural monitors  (CASTNet) than with urban monitors (AQS). Level 3 future 2020 sensitivity simulation generally yields relative response factors (RRF) between 0.75 and 0.90 with higher values (lower reductions) in core urban areas and monitor “Bayonne” with future year design value above 85 ppb and several monitors in the 75 ppb level.

Modeling climate change effects on dynamics of allergenic Ambrosia (ragweed) and Artemisia (mugwort) pollen in US
Yong Zhang, Leonard Bielory, Zhongyuan Mi, Ting Cai, Panos G. Georgopoulos

Allergenic pollen acts synergistically with common air pollutants, such as ozone, to cause Allergic Airway Disease (AAD). Observed airborne pollen data from 1994 to 2011 at Fargo (North Dakota), College Station (Texas), Omaha (Nebraska), Pleasanton (California), Cherry Hill and Newark (New Jersey) in the US were studied to examine climate change effects on trends of annual mean and peak value of daily concentrations, annual production, season start, and season length of Ambrosia (ragweed) and Artemisia (mugwort) pollen. The Cooling Degree Hour (CDH) model was used to simulate start and end dates. The vegetation maps of ragweed and mugwort across US were generated based on analyses of observed airborne pollen counts and land use data. In the 2001-2010 period, ragweed was observed to flower 2-6 days earlier and its pollen season was found to be 1-8 days longer than in the 1994-2000 period. The mugwort pollen season at most of the studied stations also tended to start earlier and last for a longer duration. Pollen levels of both ragweed and mugwort changed differently for different stations. The optimum threshold CDH values of start date 2,353 and 40,213 degree hours for ragweed and mugwort, respectively. The optimum initial date and base temperature for the CDH model of start date were found to be August 1st and 30°C for ragweed; May 1st and 37°C for mugwort.