Brajesh Dubey

University of Guelph, School of Engineering, Faculty Member

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Dr. Brajesh Dubey teaches and does research in the area of Environmental Health, Sciences and Engineering. Dr. Dubey has received his PhD in Environmental Engineering Sciences from University of Florida. He has also worked as a Consulting Environmental Engineer for 4 years. His research interest include Environmental Risk and Exposure Assessment: Fate, Transport and Biological Availability of Emerging Contaminants in different Environmental Systems, Sustainable Environmental Technologies, Global Environmental Health, Water Quality and Sanitation Issues of Developing Countries and Small Islands, Physical, Chemical and Biological Processes in Natural and Engineered Systems, Environmental Nanotechnology including its Remediation Application, Fate and Transport of Manufactured Nanomaterials in the Environment including Nano-toxicity in Environmental Systems

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Noel B. Salazar

KU Leuven

Peter Simons

Trinity College Dublin

Marc Champagne

Kwantlen Polytechnic University

David Seamon

Kansas State University

Maria Brincker

University of Massachusetts, Boston

Dr.Subramaniam Karuppannan

Open University Malaysia (OUM),

K.W. Chau

Hong Kong Polytechnic University

Simon Springer

The University of Newcastle

Ernest Nnadi

Manchester Metropolitan University

Kâmil VARINCA

Adıyaman University

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Papers by Brajesh Dubey

Catalysed combustion of ammonium perchlorate, polystyrene and their composite propellants

Indian Journal of Engineering Materials Sciences, 1994

Pokhrel LR, Silva T, El Badawy AM, Tolaymat TM, Dubey B. (2011) Evaluation of aquatic toxicity of nanoscale silver, zinc oxide, titanium dioxide and cadmium selenide quantum dots, and their ionic particulates to the MetPLATE™ bioassay. 27th Int’l Conference on Soil, Sediment, Water, and Energy, O...

Pharmaceuticals in the aquatic environment: A critical appraisal of uncertainty and knowledge gaps in human health risk assessment

Technological and life cycle assessment of organics processing odour control technologies

Science of The Total Environment, 2015

As more municipalities and communities across developed world look towards implementing organic w... more As more municipalities and communities across developed world look towards implementing organic waste management programmes or upgrading existing ones, composting facilities are emerging as a popular choice. However, odour from these facilities continues to be one of the most important concerns in terms of cost &amp;amp;amp; effective mitigation. This paper provides a technological and life cycle assessment of some of the different odour control technologies and treatment methods that can be implemented in organics processing facilities. The technological assessment compared biofilters, packed tower wet scrubbers, fine mist wet scrubbers, activated carbon adsorption, thermal oxidization, oxidization chemicals and masking agents. The technologies/treatment methods were evaluated and compared based on a variety of operational, usage and cost parameters. Based on the technological assessment it was found that, biofilters and packed bed wet scrubbers are the most applicable odour control technologies for use in organics processing faculties. A life cycle assessment was then done to compare the environmental impacts of the packed-bed wet scrubber system, organic (wood-chip media) bio-filter and inorganic (synthetic media) bio-filter systems. Twelve impact categories were assessed; cumulative energy demand (CED), climate change, human toxicity, photochemical oxidant formation, metal depletion, fossil depletion, terrestrial acidification, freshwater eutrophication, marine eutrophication, terrestrial eco-toxicity, freshwater eco-toxicity and marine eco-toxicity. The results showed that for all impact categories the synthetic media biofilter had the highest environmental impact, followed by the wood chip media bio-filter system. The packed-bed system had the lowest environmental impact for all categories.

Educational Outreach and Stain Distribution Project for Identifying Copper-Treated Wood (FINAL)

Wood treated with chromated copper arsenate (CCA) will contaminate construction and demolition (C... more Wood treated with chromated copper arsenate (CCA) will contaminate construction and demolition (C&D) wood waste with metals including arsenic, unless efforts are made to sort the wood. In many cases, CCA-treated wood can be readily identified based upon its green hue or dimensions. However, for lumber, timber and plywood sorting should be augmented with technologies that can verify the presence of treatment chemicals for cases where the wood has been weathered. One of these augmentation technologies include the use of the PAN Indicator Stain, which will react with copper in treated wood to cause a distinct color change on the wood. The primary objectives of this study were to inform the wood waste disposal sector of available augmentation technologies for sorting and to distribute samples of the stain to individuals who showed interest. As part of this study packets were developed which included a sample of the stain, instructions for use of the stain, and information concerning the technologies available to augment traditional sorting practices. The availability of the stain kits was advertised through a large mail-out to C&D facilities, yard waste processing facilities, wood recyclers and to wood cogenerations plants. Furthermore the kits were made available "on the spot" at 4 different meetings. A total of 44 stain packets were distributed. Overall, the feedback received from users of the stain was positive. The stain was found to be useful for identifying whether particular structures were treated and for spot-checking mulch samples. Concerns were raised about the practicality of testing large amounts of wood using this technology. Some users, in particular those affiliated with large wood waste processing facilities, considered the stain too expensive when used in large quantities. Future work should focus on developing rapid on-line technologies for sorting CCA-treated wood at the large wood waste processing facilities. The PAN Indicator Stain is helpful for sorting small quantities of wood. However, the stain may not be practical for facilities that process many tons of waste a day. 7

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Pokhrel LR, Dubey B, Singhal N. (2012) Assessing the environmental risks from road marking glass beads. Tennessee Environmental Conference, Mar 13-14, Kingsport, TN

Pokhrel, L., and Dubey, B., 2013. Silver and Zinc Oxide Nanoparticles Cause Developmental Anomalies in the Crop Plants. Science of the Total Environment, (In-Press) (5 year Impact factor : 3.37) DOI: 10.1016/j.scitotenv.2013.02.059

Science of The Total Environment

Pokhrel LR, Silva TU, Dubey B. (2013) Modulation of silver nanoparticle toxicity by particle characteristics (size and charge) and suspension chemistry. Elsevier Environmental Health 2013, Science and Policy to Protect Future Generations, Mar 3-6, 2013, Boston, Massachusetts, USA

Pokhrel LR, Dubey B. Global scenarios of metal mining, environmental repercussions, public policies, and sustainability: A review. Critical Reviews in Environmental Science and Technology 2013, 43, 1-37

Critical Reviews in Environmental Science and Technology

With rising valuation of mineral commodities, mining has been envisioned as a profitable industry... more With rising valuation of mineral commodities, mining has been envisioned as a profitable industry regardless of many challenges it entails. This comprehensive review provides the state of knowledge about several aspects of the metal mining industry, including (a) the basic mining processes with reasons for mine closure, (b) the potential environmental and human health impacts associated with mining, (c) the potential techniques for impact mitigation, (d) the latest production statistics for the base and precious metals with identification of currently operational major metal mines for different countries, and (e) how mining activities are regulated in different nations. Finally, the authors provide critical appraisal on the debatable issue of mining and sustainability to stimulate thoughts on how metal mining can be made sustainable, and suggest a path forward.

Assessing the environmental risks from road marking glass bead

A critical review of arsenic exposures for Bangladeshi adults

Science of The Total Environment, 2015

Groundwater, the most important source of water for drinking, cooking, and irrigation in Banglade... more Groundwater, the most important source of water for drinking, cooking, and irrigation in Bangladesh, is a significant contributor to the daily human intake of arsenic. Other arsenic intake pathways, established as relevant for Bangladeshi adults through this review, include consumption of contaminated edible plant parts and animal-origin food, inhalation of contaminated air, soil ingestion, betel quid chewing, and tobacco smoking. This review qualifies and quantifies these arsenic intake pathways through analysis of the range of arsenic levels observed in different food types, water, soil, and air in Bangladesh, and highlights the contributions of dietary intake variation and cooking method in influencing arsenic exposures. This study also highlights the potential of desirable dietary patterns and intakes in increasing arsenic exposure which is relevant to Bangladesh where nutritional deficiencies and lower-than-desirable dietary intakes continue to be a major concern.

Evaluation of Experimental Design Options in Environmental Nano-Science Research

Expert Opinion on Environmental Biology, 2013

As an experimental research design plays a pivotal role in executing a research problem, it is im... more As an experimental research design plays a pivotal role in executing a research problem, it is imperative of a researcher to develop a suitable and sound research design. Utilizing robust statistical methods can further enhance the study power and thus allow drawing a logical conclusion. The same holds true for basic environmental science research, including research related to the effects of engineered nanomaterials in the environment. In this paper, we (i) provide a succinct overview of multiple experimental design options that are available to conduct environmental research with focus on emerging nanomaterial science research; (ii) outline the pros and cons of various study designs providing examples as appropriate; (iii) identify and discuss the challenges facing nanoresearchers in quantifying and characterizing nanomaterials; and (iv) provide a perspective on how these challenges can be addressed in a situation when instrumentations and protocols that have been used for conventional toxicant characterization are purportedly less suitable for gaining insights into interactions potentially occurring at bio-nano interfaces to explain nanotoxicology. This is a design in which a group of test subjects is exposed to a chemical, a drug, or any other treatment, and then the response is measured. This design does not randomize the subjects, nor does it incorporate a control group for comparison . For example, considering the necessity of understanding potential toxicity of silver nanoparticles -one of the widely used nanomaterials in commercial applications today [11] -in plants, a few seeds of a particular plant species can be treated with a single concentration of silver nanoparticles and observe for certain end points (e.g., germination rate, root/shoot growth, DNA damage) [9]. One-shot design can be particularly useful for screening the potential toxicity of any novel

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Natural water chemistry (dissolved organic carbon, pH, and hardness) modulates colloidal stability, dissolution, and antimicrobial activity of citrate functionalized silver nanoparticles

Environ. Sci.: Nano, 2014

Key understanding of potential transformations that may occur on silver nanoparticle (AgNP) surfa... more Key understanding of potential transformations that may occur on silver nanoparticle (AgNP) surface upon interaction with naturally ubiquitous organic ligands (e.g., −SH (thoil), humic acid, or −COO (carboxylate)) is limited. Herein we investigated how dissolved organic carbon (DOC), −SH (in cysteine, a well-known Ag + chelating agent), and −COO (in trolox, a well-known antioxidant) could alter the colloidal stability, dissolution rate, and toxicity of citratefunctionalized AgNPs (citrate−AgNPs) against a keystone crustacean Daphnia magna. Cysteine, DOC, or trolox amendment of citrate−AgNPs differentially modified particle size, surface properties (charge, plasmonic spectra), and ion release dynamics, thereby attenuating (with cysteine or trolox) or promoting (with DOC) AgNP toxicity. Except with DOC amendment, the combined toxicity of AgNPs and released Ag under cysteine or trolox amendment was lower than of AgNO 3 alone. The results of this study show that citrate−AgNP toxicity can be associated with oxidative stress, ion release, and the organism biology. Our evidence suggests that specific organic ligands available in the receiving waters can differentially surface modify AgNPs and alter their environmental persistence (changing dissolution dynamics) and subsequently the toxicity; hence, we caveat to generalize that surface modified nanoparticles upon environmental release may not be toxic to receptor organisms.

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Validation of QuEChERS method for the determination of 36 pesticide residues in fruits and vegetables from Ghana, using gas chromatography with electron capture and pulsed flame photometric detectors

Journal of Environmental Science and Health, Part B, 2015

In this study, &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Quick, Easy, Cheap, Effe... more In this study, &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Quick, Easy, Cheap, Effective, Rugged and Safe&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;QuEChERS&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; method was modified for the determination of 36 pesticides fortified at (0.01-1.0) mg kg(-1) in three vegetables and a fruit (lettuce, carrot, tomatoes and pineapples respectively) from Ghana. The method involved extraction with acetonitrile, phase separation with primary secondary amine and magnesium sulfate; the final injection solution was reconstituted in ethyl acetate. Organochlorine and synthetic pyrethroids residues were detected with electron capture detector whereas organophosphorus, pulsed flame photometric detector was used. The recoveries at different concentration levels (0.01, 0.1 and 1.0 mg kg(-1)) were in the range of 83% and 93% with relative standard deviation ranging from 2% to 10% (n = 5) and the coefficient of determination (R(2)) was greater than 0.99 for all the 36 pesticides. The method was successfully tested on 120 real samples from Accra markets and this proved to be useful for monitoring purposes particularly in laboratories that have no gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry.

Human health risk assessment from arsenic exposures in Bangladesh

Science of The Total Environment, 2015

High arsenic exposures, prevalent through dietary and non-dietary sources in Bangladesh, present ... more High arsenic exposures, prevalent through dietary and non-dietary sources in Bangladesh, present a major health risk to the public. A quantitative human health risk assessment is described as a result of arsenic exposure through food and water intake, tea intake, accidental soil ingestion, and chewing of betel quid, while people meet their desirable dietary intake requirements throughout their lifetime. In evaluating the contribution of each intake pathway to average daily arsenic intake, the results show that food and water intake combined, makes up approximately 98% of the daily arsenic intake with the balance contributed to by intake pathways such as tea consumption, soil ingestion, and quid consumption. Under an exposure scenario where arsenic concentration in water is at the WHO guideline (0.01mg/L), food intake is the major arsenic intake pathway ranging from 67% to 80% of the average daily arsenic intake. However, the contribution from food drops to a range of 29% to 45% for an exposure scenario where arsenic in water is at the Bangladesh standard (0.05mg/L). The lifetime excess risk of cancer occurrence from chronic arsenic exposure, considering a population of 160 million people, based on an exposure scenario with 85 million people at the WHO guideline value and 75 million people at the Bangladesh standard, and assuming that 35 million people are associated with a heavy activity level, is estimated as 1.15 million cases.

Elemental Speciation and Environmental Importance Associated with Wood Treated with Chromated Copper Arsenate

Environmental Impacts of Treated Wood, 2006

Carbon nanotube (CNT)-based novel sensors for mercury (II) detection in water

Water contamination of mercury (Hg), a highly toxic heavy metal, is a legacy problem worldwide. A... more Water contamination of mercury (Hg), a highly toxic heavy metal, is a legacy problem worldwide. Although regulations and efforts are exercised at various levels, Hg pollution from both natural and anthropogenic sources has remained a major public health and safety issue. Rapid detection of Hg at low levels is critical for rapid response and protection of public health, particularly children, pregnant and breast-feeding women, from chronic exposures to Hg in our waters. To address this longstanding issue, various types of sensors have been, and are being, developed for the detection of Hg in water. Of special interest are the rapid on-site detection and the evolving understanding of carbon nanotubes (CNTs) to agglutinate Hg (II) ions. Herein, we review currently applied and proposed methods for rapid on-site detection of Hg (II) ions using CNT-based novel detection systems, including colorimetric-, conductance-, DNAzyme-, fluorescent-, potentiometric-, and other assays. In addition, ...

Effect of moisture control and air venting on H2S production and leachate quality in mature C&D debris landfills

Environmental science & technology, Jan 21, 2014

The effect of air venting and moisture variation on H2S production and the leaching of metals/met... more The effect of air venting and moisture variation on H2S production and the leaching of metals/metalloids (arsenic, copper, chromium, and boron) from treated wood in aged mature construction and demolition (C&D) debris landfills were examined. Three simulated C&D debris landfill lysimeters were constructed and monitored, each containing as a major debris component either wooden pallets, chromated copper arsenate (CCA) treated wood, or alkaline copper quaternary (ACQ) treated wood. The lysimeters were operated with alternating periods of water addition (a total of 160 L in four equal amounts) and air venting (68.4 m(3)per day for 121 days in two phases). Moisture addition did not increase H2S levels in the long term, and a significant drop in H2S concentration was observed (up to 99%) when aerobic conditions were promoted through air venting. H2S concentrations increased after venting stopped up to values approximately two orders of magnitude lower than observed prior to venting. Vent...

Evaluation of developmental responses of two crop plants exposed to silver and zinc oxide nanoparticles

The Science of the total environment, 2013

The increasing applications of different nanomaterials in the myriad of nano-enabled products and... more The increasing applications of different nanomaterials in the myriad of nano-enabled products and their potential for leaching have raised considerable environmental, health and safety (EHS) concerns. As systematic studies investigating potential anomalies in the morphology and anatomy of crop plants are scarce, herein we report on the developmental responses of two agriculturally significant crop plants, maize (Zea mays L.) and cabbage (Brassica oleracea var. capitata L.), upon in vitro exposure to nanoparticles of citrate-coated silver (Citrate-nAg) and zinc oxide (nZnO). Analyses involve histology of the primary root morphology and anatomy using light microscopy, metal biouptake, moisture content, rate of germination, and root elongation. Comparative toxicity profiles of the ionic salts (AgNO3 and ZnSO4) are developed. Notably, we uncover structural changes in maize primary root cells upon exposure to Citrate-nAg, nZnO, AgNO3, and ZnSO4, possibly due to metal biouptake, suggestin...

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Silver and Zinc Oxide Nanoparticles Cause Developmental Toxicity to the Terrestrial Plants

Catalysed combustion of ammonium perchlorate, polystyrene and their composite propellants

Indian Journal of Engineering Materials Sciences, 1994