Pharmacology, Toxicology and Environmental Health Commons^™

Prior Exposure To Microcystin Alters Host Gut Resistome And Is Associated With Dysregulated Immune Homeostasis In Translatable Mouse Models, Punnag Saha, Dipro Bose, Vitalii Stebliankin, Trevor Cickovski, Ratanesh K. Seth, Dwayne E. Porter Ph.D., Bryan W. Brooks, Kalai Mathee, Giri Narashimhan, Rita Colwell, Geoffry Ivan Scott Ph.D., Saurabh Chatterjee Ms., Ph.D

Faculty Publications

A strong association between exposure to the common harmful algal bloom toxin microcystin and the altered host gut microbiome has been shown. We tested the hypothesis that prior exposure to the cyanotoxin microcystin-LR may alter the host resistome. We show that the mice exposed to microcystin-LR had an altered microbiome signature that harbored antibiotic resistance genes. Host resistome genotypes such as mefA, msrD, mel, ant6, and tet40 increased in diversity and relative abundance following microcystin-LR exposure. Interestingly, the increased abundance of these genes was traced to resistance to common antibiotics such as tetracycline, macrolides, glycopeptide, and aminoglycosides, crucial for modern-day …

Identifying Novel Pharmacogenetic Markers For Cancer Treatments: Exploiting Cancers Deficient In The Nucleotide Pool Sanitizing Hydrolases Nudt15 And Nudt18, Jacob Chandler Massey

Theses and Dissertations

The NUDIX hydrolases are a super family of enzymes with purported enzymatic activities of nucleotide hydrolases. The activity of the founding member, NUDT1 (also known as MTH1) is established to be a nucleotide hydrolase for d-8-oxoGTP, which is a mutagenic precursor if incorporated into DNA. Therefore, its activity serves to sanitize the nucleotide pool of mutagenic precursors. While known to be highly conserved among all organisms, the enzymatic and biological functions for nearly all the family members remain largely unexplored and unknown. Substrates of family members have been found to include canonical (deoxy)nucleotide triphosphates, oxidized (deoxy)nucleotide triphosphates, and non-nucleoside polyphosphates. …

Detection Of Microcystin Aerosol Particles, Alexis D. Dabney

Theses and Dissertations

Harmful Algal Blooms (HABs) are a growing global concern due to their increased prevalence and magnitude, frequency, and duration in affecting both aquatic ecosystems and human health (Brooks et al. 2015). In a series of experiments, lab-generated aerosol particles containing Microcystis and Microseira were captured using filters to analyze for concentrations of Microcystin, Saxitoxin, and Lyngbya toxins. The solutions were found to contain aerosols but did not contain detectable levels of Microcystin, Saxitoxin, and Lyngbya toxins following analysis by HPLC-MS. While the techniques for generating aerosols were shown to be effective, the generation and analysis of toxins did not produce …

Environmental And Biological Controls On Sedimentary Bottom Types In The Puquios Of The Salar De Llamara, Northern Chile, Erica P. Suosaari, Amanda M. Oehlert, Ioan Lascu, Alan W. Decho, Alan M. Piggot, Alvaro T. Palma, Paul F. Machabee, R. Pamela Reid

Faculty Publications

The Puquios of the Salar de Llamara in the Atacama Desert, northern Chile, is a system of small lakes that is characterized by evaporitic mineral deposition and that commonly hosts microbial communities. This region is known for its extreme aridity, solar irradiance, and temperature fluctuations. The Puquios are a highly diverse ecosystem with a variety of sedimentary bottom types. Our previous results identified electrical conductivity (EC) as a first-order environmental control on bottom types. In the present paper, we extend our analysis to examine the effects of additional environmental parameters on bottom types and to consider reasons for the importance …

Host Gut Resistome In Gulf War Chronic Multisymptom Illness Correlates With Persistent Inflammation, Dipro Bose, Somdatta Chatterjee, Ethan Older, Ratanesh Seth, Patricia Janulewicz, Punnag Saha, Ayan Mondal, Jeffrey M. Carlson, Alan W. Decho, Kimberly Sullivan, Nancy Kilmas, Stephen Lasley, Jie Li, Saurabh Chatterjee

Faculty Publications

Chronic multisymptom illness (CMI) affects a subsection of elderly and war Veterans and is associated with systemic inflammation. Here, using a mouse model of CMI and a group of Gulf War (GW) Veterans’ with CMI we show the presence of an altered host resistome. Results show that antibiotic resistance genes (ARGs) are significantly altered in the CMI group in both mice and GW Veterans when compared to control. Fecal samples from GW Veterans with persistent CMI show a significant increase of resistance to a wide class of antibiotics and exhibited an array of mobile genetic elements (MGEs) distinct from normal …

Superfund And Society Benumbed: An In-Depth Look At Environmental Justice In South Carolina, Sydney A. Hampton

Senior Theses

This thesis investigates the relationship between superfund sites in minority communities and their public health through the lens of social vulnerability. Various demographic parameters were used to assess the risk associated with minority communities and exposure to hazardous waste. After investigating the history of the Environmental Justice movement, three superfund sites of interest in South Carolina, and demographic and public health data; each community was analyzed to determine association between exposure to hazardous waste and minority status. Each examined community exhibited characteristics contributing to heightened social vulnerability, potentially causing increased susceptibility to negative health outcomes from exposure to hazardous waste.

Comparative Assessment Of The Fate And Toxicity Of Chemically And Biologically Synthesized Silver Nanoparticles Toward Juvenile Clams, Mercenaria Mercenaria, Amar Yasser Al-Rshim

Theses and Dissertations

Engineered nanomaterials (ENMs) with unique nanoscale properties, including novel optical behavior and superparamagnetic, are continually being developed for biomedical and industrial applications. In specific biomedical applications, ENMs are surface-functionalized using polymers, proteins, and other stabilizing agents to facilitate their resistance to salt-induced aggregation. Since their colloidal stability in high ionic-strength matrices, functionalized ENMs are anticipated to be persistent aquatic contaminants. Despite their potential environmental significance, the persistence of surface-functionalized ENMs as individually stabilized nanoparticles in marine environments is largely unknown. Further, few studies have investigated the fundamental factors that influence ENMs uptake and fate/transport processes in ecologically susceptible aquatic biota, …

Describing The Impact Of The Sales Of Antibiotics On The Environment And In Population Health, Andrés Gaviria-Figueroa

Theses and Dissertations

The role of antibiotics in human health is of significant importance in the advancement of the medical field. It has contributed to an improvement of the quality of life and the age expectancy of the population. Antibiotic resistance is an expected consequence of the use of antibiotics. Bacteria have developed biological mechanisms that would help them become resistant to antibiotics. The uncontrolled use of antibiotics is significantly contributing to the ability of bacteria to become resistant to those antibiotics. This study, using the model of the Socio-Ecological Coupling of Antibiotic Resistance, explains how social and environmental factors interact and impact …

Female Reproductive Toxicity Of Harmful Algal Blooms-Produced Toxin Microcystin, Yingzheng Wang

Theses and Dissertations

Harmful algal blooms (HABs) have become a global emerging environmental concern; however, its impact on women’s reproductive health is poorly understood. Microcystin-LR (MC-LR) is the most common and hazardous type of HAB toxin. Using both a chronic oral exposure mouse model and an acute exposure mouse model, I found that human-relevant exposure to MC-LR could compromise follicle ovulation via affecting follicle maturation. Both in vivo mouse exposure model and encapsulated in vitro follicle growth (eIVFG) model revealed that exposure to MC-LR did not affect follicle development, but significantly reduced the expression of some follicle maturation-related genes, such as Lhcgr and …

Transcriptomic Analysis Reveals That Municipal Wastewater Effluent Enhances Vibrio Vulnificus Growth And Virulence Potential, Karlen Enid Correa Velez, Robert Sean Norman

Faculty Publications

Vibrio vulnificusis an opportunistic pathogen indigenous to estuarine and marine environments and associated with aquatic organisms. Vibrio vulnificusis of utmost importance because it causes 95% of the seafood-related deaths in the United States due to rapid progression of septicemia. Changes in environmental parameters associated with climate change and coastal population expansion are altering geographical constraints, resulting in increased Vibrio spread, exposure, and rates of infection. In addition, coastal population expansion is resulting in increased input of treated municipal sewage into areas that are also experiencing increased Vibrio proliferation. This study aimed to better understand the influence of treated …

Assessing Stakeholder Needs And Preferences For Coastal Swimming Advisories In Charleston, South Carolina, Zachary Haynes Hart

Theses and Dissertations

The Beaches Environmental Assessment and Coastal Health (BEACH) Act was established in 2000 to reduce the risk of illness among recreational users of beaches in the United States. Specifically, the Act provides coastal states and territories with annual grants to conduct routine water quality monitoring at beaches and to notify the public when pathogen levels exceed safe thresholds. Many coastal states use beach signs, agency websites, and press releases to notify the public, but a 2011 evaluation of the public notification component of the BEACH Act found that few states are choosing methods based on target audience characteristics and interests. …

Dependence On Humidity And Aerosol Composition Of The Gas-Particle Partitioning Of Weakly And Moderately Polar Vocs, Jeonghyeon Ahn, Guiying Rao, Eric P. Vejerano

Faculty Publications

Volatile organic compounds (VOCs) dominate the class of pollutants that accumulate in the atmosphere and indoors. Assessing the gas-particle partitioning of VOCs is important to determine their fate, transport, and adverse health impacts. This work is a companion to our earlier study on the temperature dependence of VOC partitioning. Here, we report our measurement of the gas-particle partition coefficient (Kp) for weakly polar (trichloroethylene, TCE) and moderately polar (n-butanol, n-BuOH) VOCs under varying relative humidity (RH) levels onto organic and inorganic aerosols. Kp of TCE was four to five orders of magnitude lower than those …

Sars-Cov-2 Impairs Dendritic Cells And Regulates Dc-Sign Gene Expression In Tissues, Guoshuai Cai, Mulong Du, Yohan Bossé, Helmut Albrecht, Fei Qin, Xizhi Luo, Xiao Michelle Androulakis, Chao Cheng, Mitzi Nagarkatti, Prakash Nagarkatti, David C. Christiani, Michael L. Whitfield, Christopher I. Amos, Feifei Xiao

Faculty Publications

The current spreading coronavirus SARS-CoV-2 is highly infectious and pathogenic. In this study, we screened the gene expression of three host receptors (ACE2, DC-SIGN and L-SIGN) of SARS coronaviruses and dendritic cells (DCs) status in bulk and single cell transcriptomic datasets of upper airway, lung or blood of COVID-19 patients and healthy controls. In COVID-19 patients, DC-SIGN gene expression was interestingly decreased in lung DCs but increased in blood DCs. Within DCs, conventional DCs (cDCs) were depleted while plasmacytoid DCs (pDCs) were augmented in the lungs of mild COVID-19. In severe cases, we identified augmented types of immature DCs (CD22+ …

Andrographolide Attenuates Gut-Brain-Axis Associated Pathology In Gulf War Illness By Modulating Bacteriome-Virome Associated Inflammation And Microglia-Neuron Proinflammatory Crosstalk, Punnag Saha, Peter T. Skidmore, Larinda A. Holland, Ayan Mondal, Dipro Bose, Ratanesh K. Seth, Kimberly Sullivan, Patricia A. Janulewicz, Ronnie Horner, Nancy Klimas, Mitzi Nagarkatti, Prakash Nagarkatti, Efrem S. Lim, Saurabh Chatterjee

Faculty Publications

Gulf War Illness (GWI) is a chronic multi-symptomatic illness that is associated with fatigue, pain, cognitive deficits, and gastrointestinal disturbances and presents a significant challenge to treat in clinics. Our previous studies show a role of an altered Gut-Brain axis pathology in disease development and symptom persistence in GWI. The present study utilizes a mouse model of GWI to study the role of a labdane diterpenoid andrographolide (AG) to attenuate the Gut-Brain axis-linked pathology. Results showed that AG treatment in mice (100 mg/kg) via oral gavage restored bacteriome alterations, significantly increased probiotic bacteria , , and , the genera that …

Uptake, Acuumulation, And Toixicity Of Silver Nanoparticles To Juvenile Bivalve Mollusc’S Hard Clam Mercenaria Mercenaria, Hanaa Radhi Jolan Al Hameed

Theses and Dissertations

Nanoscience and nanotechnology have gained attention in the last 20 - 30 years. Manufactured nanoparticles (NPs), which are defined as having at least one dimension between 1 and 100 nm, are the main products of nanotechnology. Nanoscale materials often have novel properties due to their size and this has made them so attractive for a range of processes and sectors. These attractive properties have enhanced their use in a wide range of consumer products and applications including electronic, biomedical, and pharmaceutical. The overall objective of this dissertation was: 1) to investigate the transformation of well-characterized AgNPs, at environmentally relevant concentrations …

Partitioning Of Volatile Organic Compounds Into The Multiple Environmental Compartments, Jeonghyeon Ahn

Theses and Dissertations

Volatile organic compounds (VOCs) dominate the class of pollutants that accumulate in the atmosphere and indoors. Partitioning coefficient is a measure of a compound’s ability to distribute between two phases. Assessing the partitioning of VOCs is essential to determine their transport, fate, behavior, and adverse environmental and health impacts across multiple environmental compartments. Studies on VOC partitioning have been limited because discriminating the small mass fraction of VOCs in aerosol particles is difficult to quantify. The partitioning of VOCs into soil, air, and aerosol particle phases was investigated under dynamic laboratory conditions. A bench-scale system that precisely controlled the relative …

Nanoantibiotics: Functions And Properties At The Nanoscale To Combat Antibiotic Resistance, M. Mustafa Mamun, Adeola Julian Sorinolu, Mariya Munir, Eric P. Vejerano

Faculty Publications

One primary mechanism for bacteria developing resistance is frequent exposure to antibiotics. Nanoantibiotics (nAbts) is one of the strategies being explored to counteract the surge of antibiotic resistant bacteria. nAbts are antibiotic molecules encapsulated with engineered nanoparticles (NPs) or artificially synthesized pure antibiotics with a size range of ≤100 nm in at least one dimension. NPs may restore drug efficacy because of their nanoscale functionalities. As carriers and delivery agents, nAbts can reach target sites inside a bacterium by crossing the cell membrane, interfering with cellular components, and damaging metabolic machinery. Nanoscale systems deliver antibiotics at enormous particle number concentrations. …

Environmentally Persistent Free Radicals As Sources Of Pops, Eric P. Vejerano, Jeonghyeon Ahn, Junaid Latif, Mustafa Mamun

Faculty Publications

Environmentally persistent free radicals (EPFRs) are a new class organic pollutant sharing some of the attributes of persistent organic pollutants (POPs). This opinion/short review aims to describe the properties of EPFRs that merit their recognition as an additional and potentially significant source of POPs. EPFRs are ubiquitous in diverse environments because of multiple factors: (1) organic precursors from anthropogenic, biogenic, and other natural emission sources are abundant; multiple mechanisms in PM and soils form (2) EPFRs; and (3) EPFRs are stable and persist for a long time, thereby, accumulate in the environment and potentially transported long range. The hazards of …

The Interactive Effects Of Nontoxic Levels Of Microplastics - Textile Microfibers And Tire Wear Particles, On The Acute Toxicity Of Bifenthrin In The Estuarine Grass Shrimp, Palaemonetes Pugio, Xiaoxuan Fan

Theses and Dissertations

Contemporary pollution issues are primarily focused on Contaminants of Emerging Concern (CECs) which may include Brominated and Fluorinated flame retardants, Pharmaceuticals and Personal Care Products (PPCPs), Contemporary Use Pesticides (CUPs), nanomaterials and microplastics (Muraya et al., 2014). Tire wear particles and textile microfibers are examples of CECs which may gradually increase in the environment and may cause adverse effect on the health of some aquatic species (Marwood et al., 2011; Taylor et al., 2016). Microplastic particles are so small that they can be ingested by many marine species such as filter feeders and small particle feeders including mollusk and crustaceans, …

Health Communication Blindspot: A Case Study Of Harmful Algal Blooms In The South (Habits), Jaron Hoani King

Theses and Dissertations

A Harmful Algal Bloom (HAB) is a complex natural event that occurs when algae is in its growth stage and creates a harmful toxin as waste. HABs create both ecologic and public health challenges. The hypothesis of this thesis is that state and federal governments have different readability scores when compared side-by-side as measured by Simple Measures of Gobbledygook (SMOG). Because governments are the entity that most often claims responsibility for shared resources, this case study represents a snapshot of current governmental messaging about HABs in the South Atlantic states. These states have a long history of HAB events in …

Characterization, Bio-Uptake And Toxicity Of Polymer-Coated Silver Nanoparticles And Their Interaction With Human Peripheral Blood Mononuclear Cells, Sahar Pourhoseini, Reilly T. Enos, Angela E. Murphy, Bo Cai Ph.D., Jamie Lead

Faculty Publications

Silver nanoparticles (AgNPs) are widely used in medical applications due to their antibacterial and antiviral properties. Despite the extensive study of AgNPs, their toxicity and their effect on human health is poorly understood, as a result of issues such as poor control of NP properties and lack of proper characterization. The aim of this study was to investigate the combined characterization, bio-uptake, and toxicity of well-characterized polyvinylpyrrolidone (PVP)-coated AgNPs in exposure media during exposure time using primary human cells (peripheral blood mononuclear cells (PBMCs)). AgNPs were synthesized in-house and characterized using a multimethod approach. Results indicated the transformation of NPs …

Coastlines, Coastal Cities, And Climate Change: A Perspective On Urgent Research Needs In The United States, Paul A. Sandifer, Geoffrey I. Scott Ph.D.

Faculty Publications

This paper builds upon Friedman et al. (2020) and other reviews and statements but provides an explicit focus on research needed to improve the resilience and survivability of coastal communities as they face existential threats from climate change. It does not attempt a prescriptive analysis of potential research emphases, but instead recommends some key research areas that we believe will help provide a solid foundation for community adaptation. Our perspective is based on our experiences over a combined nearly 95 years of work in research, management, and policy, much of it related to coastal environments and their communities, rather than …

Use Of Single Particle Icp-Ms To Estimate Silver Nanoparticle Penetration Through Baby Porcine Mucosa, Ilaria Zanoni, Matteo Crosera, Elena Pavoni, Gianpiero Adami, Marcella Mauro, Anna Luisa Costa, Jamie Lead, Francesca Larese Filon

Faculty Publications

Children are potentially exposed to products that contain nanoparticles (NPs). In particular, silver NPs are commonly present both in products used by and around children, primarily due to their antibacterial properties. However, very few data are available regarding the ability of silver NPs to penetrate through the oral mucosa in children. In the present work, we used baby porcine buccal mucosa mounted on vertical Franz diffusion cells, as an in vitro model to investigate penetration of silver NPs (19 ± 5 nm). Permeability experiments were performed using pristine physiologically-relevant saline solution in the receiver chamber and known concentrations of NPs …

Transport Of N-Cd And Pre-Sorbed Pb In Saturated Porous Media, Salahaddin Kamrani, Vahab Amiri, Mosleh Kamrani, Mohammed Baalousha

Faculty Publications

Carbon dots (CDs) are a new type of nanomaterials of the carbon family with unique characteristics, such as their small size (e.g., <10 nm), high water solubility, low toxicity, and high metal affinity. Modification of CDs by Nitrogen functional groups (N-CDs) enhances their metal adsorption capacity. This study investigated the influences of pH (4, 6, and 9), ionic strength (1, 50, and 100 mM), and cation valency (Na⁺ and Ca²⁺) on the competitive adsorption of Pb to quartz and N-CD surfaces, the transport and retention of N-CDs in saturated porous media, and the capacity of N-CDs to mobilize pre-adsorbed Pb in quartz columns. Pb adsorption was higher on N-CDs than on quartz surfaces and decreased with increases in ionic strength (IS) and divalent cations (Ca²⁺) concentration. N-CD mobility in quartz columns was highest at pH of 9- and 1-mM monovalent cations …

Identifying Seasonal And Daily Variations In Arg-Containing Bioaerosols Generated During The Wastewater Treatment Process, Mirza Isanovic

Theses and Dissertations

Antibiotic resistance is a growing problem with the current global death count topping 700,000. In the United States alone there are 2.8 million antibiotic resistant bacterial (ARB) infections each year and approximately 35,000 deaths. If current trends continue the global ARB death count will reach 10 million surpassing current chronic disease deaths. Wastewater treatment plants play a vital role in protecting both the environment as well as local communities. The WWTP process allows for the removal of chemicals and contaminants from water that eventually makes its way back into the environment as well as into drinking water plants. Despite the …

Obesity Worsens Gulf War Illness Symptom Persistence Pathology By Linking Altered Gut Microbiome Species To Long-Term Gastrointestinal, Hepatic, And Neuronal Inflammation In A Mouse Model, Dipro Bose, Punnag Saha, Ayan Mondal, Brian Fanelli, Ratanesh K. Seth, Patricia Janulewicz, Kimberly Sullivan, Stephen Lasley, Ronnie Horner, Rita R. Colwell, Ashok K. Shetty, Nancy Klimas, Saurabh Chatterjee

Faculty Publications

Persistence of Gulf War illness (GWI) pathology among deployed veterans is a clinical challenge even after almost three decades. Recent studies show a higher prevalence of obesity and metabolic disturbances among Gulf War veterans primarily due to the existence of post-traumatic stress disorder (PTSD), chronic fatigue, sedentary lifestyle, and consumption of a high-carbohydrate/high-fat diet. We test the hypothesis that obesity from a Western-style diet alters host gut microbial species and worsens gastrointestinal and neuroinflammatory symptom persistence. We used a 5 month Western diet feeding in mice that received prior Gulf War (GW) chemical exposure to mimic the home phase obese …

A Method To Measure The Partitioning Coefficient Of Volatile Organic Compounds In Nanoparticles, Guiying Rao, Jeonghyeon Ahn, Abigail Evans, Michelle Casey, Eric P. Vejerano

Faculty Publications

The partitioning behavior of volatile organic compounds (VOCs) into nanoparticles is less studied compared to those of semivolatile organic compounds (SVOCs) because of the lower concentration of the VOCs that is expected to partition into particles. One challenge in measuring the accurate partition coefficient of VOCs is quantifying their low mass fraction that sorbed on nanoparticles and differentiating them from the high VOC concentrations present in the gas-phase. Systematically characterizing the partitioning coefficient at a specific environmental condition is also difficult when sampling in the field. During field sampling, thermal and non-thermal issues such as sampling artifacts and non-equilibrium conditions …

Tlr Antagonism By Sparstolonin B Alters Microbial Signature And Modulates Gastrointestinal And Neuronal Inflammation In Gulf War Illness Preclinical Model, Dipro Bose, Ayan Mondal, Punnag Saha, Diana Kimono, Sutapa Sarkar, Ratanesh K. Seth, Patricia Janulewicz, Kimberly Sullivan, Ronnie Horner, Nancy Klimas, Mitzi Nagarkatti, Prakash Nagarkatti, Saurabh Chatterjee

Faculty Publications

The 1991 Persian Gulf War veterans presented a myriad of symptoms that ranged from chronic pain, fatigue, gastrointestinal disturbances, and cognitive deficits. Currently, no therapeutic regimen exists to treat the plethora of chronic symptoms though newer pharmacological targets such as microbiome have been identified recently. Toll-like receptor 4 (TLR4) antagonism in systemic inflammatory diseases have been tried before with limited success, but strategies with broad-spectrum TLR4 antagonists and their ability to modulate the host-microbiome have been elusive. Using a mouse model of Gulf War Illness, we show that a nutraceutical, derived from a Chinese herb Sparstolonin B (SsnB) presented a …

Lipocalin 2 Induces Neuroinflammation And Blood-Brain Barrier Dysfunction Through Liver-Brain Axis In Murine Model Of Nonalcoholic Steatohepatitis, Ayan Mondal, Dipro Bose, Punnag Saha, Sutapa Sarkar, Ratanesh K. Seth, Diana Kimono, Muayad Albadrani, Mitzi Nagarkatti, Prakash Nagarkatti, Saurabh Chatterjee

Faculty Publications

BACKGROUND:

Recent clinical and basic research implicated a strong correlation between NAFLD/NASH phenotypes with ectopic manifestations including neuroinflammation and neurodegeneration, but the mediators and critical pathways involved are not well understood. Lipocalin 2 (Lcn2) is one of the important mediators exclusively produced in the liver and circulation during NASH pathology.

METHODS:

Using murine model of NASH, we studied the role of Lcn2 as a potent mediator of neuroinflammation and neurodegeneration in NASH pathology via the liver-brain axis. RESULTS: Results showed that high circulatory Lcn2 activated 24p3R (Lipocalin2 receptor) in the brain and induced the release of high mobility group box …

A Letter To Reconsider The Conditions For Testing Decontaminated N95 Respirators For Emergency Reuse To Address Shortage, Eric P. Vejerano, Jeonghyeon Ahn

Faculty Publications

The battle with COVID-19 pandemic has resulted in the shortage of personal protective equipment, particularly, N95 respirators. Healthcare workers who reused N95 respirators may resort to unproven methods of cleaning/sterilization that can severely compromise the respirators’ filtration efficiency. A recently issued guideline will test decontaminated N95 respirators against particles with a median diameter of 0.075 ± 0.020 µm at a flow rate of 85 L min–1. For emergency reuse, these conditions may be too stringent. N95 respirators tested at this flow rate had predicted efficiencies of < 69%, assuming complete degradation of their electrostatic coating. Experimental efficiencies were ~15% lower. For emergency reuse, we recommend to either adjust the flow rate closer to normal breathing, or the size of the test particle should reflect that of virus-laden respiratory aerosols (~> 0.5 µm). By reconsidering the test conditions, a substantial fraction of used/decontaminated respirators can …