Reviews of environmental contamination and toxicology

Volume 234

David M. Whitacre Editor

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Reviews of
Environmental Contamination
and Toxicology
VOLUME 234

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Reviews of
Environmental Contamination
and Toxicology
Editor

David M. Whitacre

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VOLUME 234


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Foreword

International concern in scientific, industrial, and governmental communities over

traces of xenobiotics in foods and in both abiotic and biotic environments has justified the present triumvirate of specialized publications in this field: comprehensive
reviews, rapidly published research papers and progress reports, and archival documentations. These three international publications are integrated and scheduled to
provide the coherency essential for nonduplicative and current progress in a field as
dynamic and complex as environmental contamination and toxicology. This series
is reserved exclusively for the diversified literature on “toxic” chemicals in our
food, our feeds, our homes, recreational and working surroundings, our domestic
animals, our wildlife, and ourselves. Tremendous efforts worldwide have been
mobilized to evaluate the nature, presence, magnitude, fate, and toxicology of the
chemicals loosed upon the Earth. Among the sequelae of this broad new emphasis
is an undeniable need for an articulated set of authoritative publications, where one
can find the latest important world literature produced by these emerging areas of
science together with documentation of pertinent ancillary legislation.
Research directors and legislative or administrative advisers do not have the time
to scan the escalating number of technical publications that may contain articles
important to current responsibility. Rather, these individuals need the background
provided by detailed reviews and the assurance that the latest information is made
available to them, all with minimal literature searching. Similarly, the scientist
assigned or attracted to a new problem is required to glean all literature pertinent to
the task, to publish new developments or important new experimental details
quickly, to inform others of findings that might alter their own efforts, and eventually to publish all his/her supporting data and conclusions for archival purposes.
In the fields of environmental contamination and toxicology, the sum of these
concerns and responsibilities is decisively addressed by the uniform, encompassing,
and timely publication format of the Springer triumvirate:
Reviews of Environmental Contamination and Toxicology [Vol. 1 through 97
(1962–1986) as Residue Reviews] for detailed review articles concerned with

v


vi

Foreword

any aspects of chemical contaminants, including pesticides, in the total environment with toxicological considerations and consequences.
Bulletin of Environmental Contamination and Toxicology (Vol. 1 in 1966) for
rapid publication of short reports of significant advances and discoveries in the
fields of air, soil, water, and food contamination and pollution as well as methodology and other disciplines concerned with the introduction, presence, and
effects of toxicants in the total environment.
Archives of Environmental Contamination and Toxicology (Vol. 1 in 1973) for
important complete articles emphasizing and describing original experimental or
theoretical research work pertaining to the scientific aspects of chemical contaminants in the environment.
Manuscripts for Reviews and the Archives are in identical formats and are peer
reviewed by scientists in the field for adequacy and value; manuscripts for the
Bulletin are also reviewed, but are published by photo-offset from camera-ready
copy to provide the latest results with minimum delay. The individual editors of
these three publications comprise the joint Coordinating Board of Editors with
referral within the board of manuscripts submitted to one publication but deemed by
major emphasis or length more suitable for one of the others.
Coordinating Board of Editors


Preface

The role of Reviews is to publish detailed scientific review articles on all aspects of
environmental contamination and associated toxicological consequences. Such articles
facilitate the often complex task of accessing and interpreting cogent scientific data
within the confines of one or more closely related research fields.
In the nearly 50 years since Reviews of Environmental Contamination and
Toxicology ( formerly Residue Reviews) was first published, the number, scope, and
complexity of environmental pollution incidents have grown unabated. During this

entire period, the emphasis has been on publishing articles that address the presence
and toxicity of environmental contaminants. New research is published each year on
a myriad of environmental pollution issues facing people worldwide. This fact, and
the routine discovery and reporting of new environmental contamination cases, creates an increasingly important function for Reviews.
The staggering volume of scientific literature demands remedy by which data
can be synthesized and made available to readers in an abridged form. Reviews
addresses this need and provides detailed reviews worldwide to key scientists and
science or policy administrators, whether employed by government, universities, or
the private sector.
There is a panoply of environmental issues and concerns on which many scientists have focused their research in past years. The scope of this list is quite broad,
encompassing environmental events globally that affect marine and terrestrial ecosystems; biotic and abiotic environments; impacts on plants, humans, and wildlife;
and pollutants, both chemical and radioactive; as well as the ravages of environmental disease in virtually all environmental media (soil, water, air). New or enhanced
safety and environmental concerns have emerged in the last decade to be added to
incidents covered by the media, studied by scientists, and addressed by governmental and private institutions. Among these are events so striking that they are creating
a paradigm shift. Two in particular are at the center of everincreasing media as well
as scientific attention: bioterrorism and global warming. Unfortunately, these very
worrisome issues are now superimposed on the already extensive list of ongoing
environmental challenges.

vii


viii

Preface

The ultimate role of publishing scientific research is to enhance understanding of
the environment in ways that allow the public to be better informed. The term
“informed public” as used by Thomas Jefferson in the age of enlightenment conveyed the thought of soundness and good judgment. In the modern sense, being
“well informed” has the narrower meaning of having access to sufficient information. Because the public still gets most of its information on science and technology

from TV news and reports, the role for scientists as interpreters and brokers of scientific information to the public will grow rather than diminish. Environmentalism
is the newest global political force, resulting in the emergence of multinational consortia to control pollution and the evolution of the environmental ethic.Will the new
politics of the twenty-first century involve a consortium of technologists and environmentalists, or a progressive confrontation? These matters are of genuine concern
to governmental agencies and legislative bodies around the world.
For those who make the decisions about how our planet is managed, there is an
ongoing need for continual surveillance and intelligent controls to avoid endangering the environment, public health, and wildlife. Ensuring safety-in-use of the many
chemicals involved in our highly industrialized culture is a dynamic challenge, for
the old, established materials are continually being displaced by newly developed
molecules more acceptable to federal and state regulatory agencies, public health
officials, and environmentalists.
Reviews publishes synoptic articles designed to treat the presence, fate, and, if
possible, the safety of xenobiotics in any segment of the environment. These reviews
can be either general or specific, but properly lie in the domains of analytical chemistry and its methodology, biochemistry, human and animal medicine, legislation,
pharmacology, physiology, toxicology, and regulation. Certain affairs in food technology concerned specifically with pesticide and other food-additive problems may
also be appropriate.
Because manuscripts are published in the order in which they are received in
final form, it may seem that some important aspects have been neglected at times.
However, these apparent omissions are recognized, and pertinent manuscripts are
likely in preparation or planned. The field is so very large and the interests in it are
so varied that the editor and the editorial board earnestly solicit authors and suggestions of underrepresented topics to make this international book series yet more
useful and worthwhile.
Justification for the preparation of any review for this book series is that it deals
with some aspect of the many real problems arising from the presence of foreign
chemicals in our surroundings. Thus, manuscripts may encompass case studies
from any country. Food additives, including pesticides, or their metabolites that may
persist into human food and animal feeds are within this scope. Additionally, chemical contamination in any manner of air, water, soil, or plant or animal life is within
these objectives and their purview.


Preface

ix

Manuscripts are often contributed by invitation. However, nominations for new
topics or topics in areas that are rapidly advancing are welcome. Preliminary communication with the editor is recommended before volunteered review manuscripts
are submitted.
Summerfield, NC, USA

David M. Whitacre



Contents

Release, Transport and Toxicity of Engineered Nanoparticles ...................
Deepika Soni, Pravin K. Naoghare, Sivanesan Saravanadevi,
and Ram Avatar Pandey
Source Characterization of Polycyclic Aromatic Hydrocarbons
by Using Their Molecular Indices: An Overview of Possibilities ...............
Efstathios Stogiannidis and Remi Laane

1

49

Respiratory and Cardiovascular Effects of Metals
in Ambient Particulate Matter: A Critical Review ...................................... 135
Deborah L. Gray, Lance A. Wallace, Marielle C. Brinkman,
Stephanie S. Buehler, and Chris La Londe
Index ................................................................................................................. 205

xi


Release, Transport and Toxicity
of Engineered Nanoparticles
Deepika Soni, Pravin K. Naoghare, Sivanesan Saravanadevi,
and Ram Avatar Pandey

Contents
1Introduction...........................................................................................................................2
2 Engineered Nanoparticles and Their Applications................................................................6
3 Release Pathways of Engineered Nanoparticles in the Environment....................................9
4 Fate and Transport of Engineered Nanoparticles in the Environment..................................12
4.1 Air.................................................................................................................................12
4.2 Water.............................................................................................................................. 14
4.3 Soil................................................................................................................................ 15
5 Toxicity of the ENPs.............................................................................................................16
5.1 Microbes.......................................................................................................................16
5.2 Animals.........................................................................................................................24
5.3 Plants ............................................................................................................................29
5.4 Toxicity to Different Cell Lines...................................................................................32

D. Soni
Environmental Biotechnology Division, National Environmental Engineering Research
Institute [CSIR-NEERI], Nehru Marg, Nagpur 440020, India
Environmental Health Division, National Environmental Engineering Research Institute
[CSIR-NEERI], Nehru Marg, Nagpur 440020, India
P.K. Naoghare • S. Saravanadevi (*)
Environmental Health Division, National Environmental Engineering Research Institute

[CSIR-NEERI], Nehru Marg, Nagpur 440020, India
R.A. Pandey (*)
Environmental Biotechnology Division, National Environmental Engineering Research
Institute [CSIR-NEERI], Nehru Marg, Nagpur 440020, India
e-mail:
© Springer International Publishing Switzerland 2015
D.M. Whitacre (ed.), Reviews of Environmental Contamination and Toxicology
Volume 234, Reviews of Environmental Contamination and Toxicology 234,
DOI 10.1007/978-3-319-10638-0_1

1


2

D. Soni et al.

6 Possible Mechanisms by Which Nanoparticles Induce Toxicity..........................................35
6.1 Generation of ROS.......................................................................................................35
6.2 Interaction with Proteins..............................................................................................36
6.3 DNA Damage...............................................................................................................37
7Summary...............................................................................................................................38
References...................................................................................................................................39

1  Introduction
Nanotechnology is associated with the design and application of nanoscale particles
(viz., 1–100 nm) that possess properties that are quite different from their bulk counterparts. The Royal Society and Royal Academy of Engineering offer the following
definition for this term: “Nanotechnologies are the design, characterization, production and application of structures, devices, and systems by controlling shape and
size at nanometer scale” (Royal Society and Royal Academy of Engineering 2004).
Different types of engineered nanoparticles (ENPs) are presently synthesized and

utilized for multiple applications. These include particles that are made of carbon,
metal and metal-oxide and quantum dots (QDs) (see Table 1 for a list of abbreviations
and acronyms). ENPs have specific physico-chemical properties that are utilized for
applications that have social and economic benefit. Metal nanoparticles are used in
medicine and have great antibacterial potential (Chopra 2007). ZnO and TiO2 nanoparticles have light-scattering potential and are used to protect against harmful UV
light (Rodríguez and Fernández-García 2007). ENPs have also proved to be potential drug delivery agents (Alivisatos 2004; Gibson et al. 2007; Huber 2005; Tsai et al.
2007). ENPs are efficient scrubbers of gaseous pollutant like carbon dioxide (CO2),
nitrogen oxides (NOx), and sulphur oxides (SOx) (Schmitz and Baird 2002). Moreover,
ENPs are used for applications in environmental remediation (Zhang 2003).
Scientists and economists have predicted that ENP-based processes and technology will increasingly be used in nanotechnology research and development (Guzman
et al. 2006). It has been estimated that the value of nanotechnology products will
reach $1 trillion by 2015 and will employ about two million workers (Nel et al.
2006; Roco and Bainbridge 2005).
The increased growth of nano-based products for multiple applications will ultimately be the source of their expanded release to air, water and soil (Nowack and
Bucheli 2007). Nanomaterial wastes are released into the environment from operating or disposing of nanodevices and during nanomaterial manufacturing processes.
Such releases may be dangerous because of the small size of the particles involved,
i.e., such particles can float into the air, be chemically transformed, and can affect
water quality and/or accumulate in soils. Moreover, ENPs can be easily transported
to animal and plant cells, either directly or indirectly, and cause unknown effects.
The dearth of information on environmental transport and safety has raised concerns among the public and among scientific authorities. There is a desire to know
much more about the fate and behavior of ENPs in the environment and in biological systems. Nanotechnology is still in its infancy, and it is critical that action be
taken to evaluate the potential adverse effects that ENPs may have on organisms and


Release, Transport and Toxicity of Engineered Nanoparticles

3

Table 1  Abbreviations and acronyms used in this paper
Abbreviations

8-OHdG
A549 cells
AB
AFM
Ag
AK
Al
Al13 or Al30
Al2O3
APATP
ATM
Au
BaO
BEAS-2B
BRL 3A
BSA
C-18-4
Ca
CaCl2
CaO
CAT
Cd
CdSe
CdSe/ZnS
CdTe
CeO2
CHO-K1
CNTs
CO
CO2

Cu4S6
CYP1A
CYP2D6*2
D
daf-12
DEB
DOC
DWNTs
EDS
EDTA
ENPs
ETC

Acronyms
8-hydroxyl deoxyguanosine
Human lung cell line
Alamar blue
Atomic Force Microscopy
Silver
Adenylate kinase
Aluminium
polynuclear complexes of aluminium
Aluminium oxide
As prepared
Adenosine Triphosphate
Ataxia Telangiectasia Mutant
Gold
Barium oxide
Human bronchial epithelial cell lines
Rat liver cell lines

Bovine Serum Albumin
Mouse spermatogonial stem cells
Calcium
Calcium chloride
Calcium oxide
Catalase
Cadmium
Cadmium selenide
Cadmium selenide/zinc sulphide
Cadmium telluride
Cerium oxide
Chinese Hamster Ovary
Carbon nanotubes
Carbon monoxide
Carbon dioxide
Complex of sulfides
Cytochrome P450 1A
Cytochrome P450 2D6
Particle diffusivity
dauer formation protein
Dynamic Energy Budget
Dissolved Organic Carbon
Double walled nanotubes
Electron Dispersive X-ray analysis
Ethylene diamine tetra acetic acid
Engineered nanoparticles
Electron Transport Chain
(continued)

4

D. Soni et al.

Table 1 (continued)
Abbreviations
Fe
Fe2O3 and Fe3O4
Fe3O4
FeO
FPW
FTIR
GSH
GSH-px
GST
GSTM1
H[AuCl4]
H2O2
HDF
HepG2
HSP 70
IL-8
InP
KCl
KNO3
LC50
LDH
LED
LTC
M

MAP
MBC
MDA
MgO
MIC
MNP
MRI
MT
MTT
MWNT
NO
NOM
NOx
NQO1
NR
nZVI
O2¯˙
PAHs

Acronyms
Iron
Iron oxide
Magnetite
Wustite or Iron (II) oxide
Filtered Pond Water
Fourier Transform Infrared
Total glutathione
Glutathione peroxidase
Glutathione S transferase
Glutathione-S-transferase M1

Chloroauric acid
Hydrogen peroxide
Human dermal fibroblast
Human liver carcinoma
Heat shock protein 70
Interleukin-8
Indium phosphide
Potassium chloride
Potassium nitrate
Lethal concentration
Lactate dehydrogenase
Light emitting diodes
Low Temperature Carbonization
Mass of the particle
Monoammonium phosphate
Minimum bactericidal concentration
Malonyldialdehyde
Magnesium oxide
Minimum inhibitory concentration
Magnetic nanoparticles
Magnetic resonance imaging
Metallothionein
3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide
Multi walled nanotubes
Nitrous oxide
Natural organic matter
Nitrogen oxides
NAD(P)H quinine oxidoreductase 1
Neutral red
Nano zero valent iron

Superoxide radical
Poly aromatic hydrocarbons
(continued)


Release, Transport and Toxicity of Engineered Nanoparticles

5

Table 1 (continued)
Abbreviations
PbSe
PC 12 M
pHzpc
PPY
PVP
QDs
RAW-264.7
RBEC
ROS
SDS
Se
SEM
SH
SiO2
SO2
SOD
Sod-3
SOx
SWNT

T
T
TEM
TGA
THP-1
TiO2
TNF-α
U
UV-B
X
XAS
ZnO
ZrO2
α-Fe2O3
γ-Fe2O3
γ-H2AX
Ζ
Κ

Acronyms
Lead selenide
Rat pheochromocytoma cell line
pH at zero point charge
Proteose peptone yeast extract medium
Poly vinyl pyrolidone
Quantum dots
Human macrophage cell lines
Rat brain endothelial cell
Reactive oxygen species
Sodium dodecyl sulphate

Selenium
Scanning electron microscope
Sulfhydryls
Silicon dioxide
Sulphur dioxide
Superoxide dismutase
Superoxide dismutase-3
Sulphur oxides
Single walled nanotubes
Time
Translational energy of a gas molecule
Transmission electron microscope
Thermogravimetric Analysis
Human monocytic cell line
Titanium dioxide
Tumor necrosis factor
Velocity
Ultraviolet light
Direction coordinate
X-ray absorption spectroscopy
Zinc oxide
Zirconium oxide
Hematite
Maghemite
Histone H2AX
Friction coefficient
Boltzmann constant

on the environment (Nel et al. 2006; Colvin 2002). Although reports have been
published on the potential safety of ENPs, few details on their transport, fate and

toxicity are currently available.


6

D. Soni et al.

In this review, we address the release and transport of ENPs to the environment
and summarize the deleterious effects they have been observed to induce on different organisms. Several important issues that impinge on the environmental ­behavior
and safety of ENPs are addressed. These include the mobility of ENPs in different
environmental media (e.g., air, water and soil), their toxicity on different organisms,
and the possible pathways by which the ENPs may produce their toxicity.

2  Engineered Nanoparticles and Their Applications
Since time immemorial, organisms and the environment have been exposed to natural nanoparticles like volcanic dust, ash, combustion by-products (e.g., carbon
black, soot), organic matter like humic and fulvic acids, proteins, peptides and colloidal inorganic species present in natural water and in soil systems (Fig. 1) (Buffle
2006). In contrast to nascent and incidental nanoparticles, ENPs are produced by
processing materials at the nano scale.
ENPs are composed of carbon, metal and metal-oxides, semiconductors (quantum dots (QDs) and polymers (dendrimers)). Carbon-based nanoparticles include
buckminsterfullerene, a C60 molecule that resembles the stitching pattern evident on

Organic matters

Nascent

Soil particles, clay

Carbon black, soot, ash
Nanoparticles

Fullerene, CNT

Metals
Engineered
Metal oxides

Quantum dots

Fig. 1  An outline of nanoparticle types that can be released to the environment


Release, Transport and Toxicity of Engineered Nanoparticles

7

a soccer ball and has 60 carbon atoms arranged as 12 pentagons and 20 hexagons.
Other fullerene nanoparticles also exist (e.g., C70, C74, C76, C78, etc.). Fullerenes are
hydrophobic and have application as organic photovoltaics, antioxidants, catalysts,
polymers, in water purification, bio-hazard protective agents, and in various medical
and pharmaceutical applications (Yadav and Kumar 2008). Carbon nanotubes
(CNTs) are also important. CNTs include single- and multi-walled nanotubes
(SWNTs and MWNTs) that are cylindrical in shape. CNTs possess excellent tensile
strength and elasticity and show different metallic and kinetic properties that vary by
their size. For example, high tensile strength carbon nanotubes (CNTs) have applications in the electronic and polymer industries (Koehler et al. 2008; Wu et al. 2004;
Table 2). Moreover, the energy sector and the consumer goods industries are doing
research with this unique material (Koehler et al. 2008). CNTs promise to have
interesting future applications by being integrated into polymers (Chang et al. 2005)
and into lithium ion secondary batteries (Ouellette 2003). The demand for carbonbased nanoparticles in the market, especially in the electronics and polymer sectors,
is enormous and is estimated to reach $1.096 billion by 2015 (Garland 2009).
Metal nanoparticles are made by manipulating heavy metals like gold, silver, iron

and platinum. Such ENPs possess specific properties that are based on their shape,
size and dissolution medium. Different routes have been used to synthesize these
nanoparticles; recently, green synthesis methods have been utilized to make silver
and iron nanoparticles (Ramteke et al. 2010, 2012; Sahu et al. 2012; Shankar et al.
2003). Metal nanoparticles have many uses and new ones are routinely being discovered. For example, colloidal gold is used to treat rheumatoid arthritis in an animal
model (Tsai et al. 2007), is used as a drug carrier (Gibson et al. 2007) and as an agent
for detecting tumors (Qian et al. 2008). Colloidal gold has also been used as a contrast agent for biological probes like antibodies, nucleic acids, glycans and receptors
(Horisberger and Rosset 1977) (Table 2). Silver nanoparticles are used in medicine
(Table 2) as a disinfectant, antiseptic, in surgical masks, and in wound dressings that
have anti-bacterial activity (Chopra 2007). Many textiles, keyboards, cosmetics,
water purifier appliances, plastics and biomedical devices are now known to contain
silver nanoparticles that provide protection against microorganisms (Li et al. 2010).
Iron nanoparticles are utilized in magnetic recording media and tapes, as a catalyst in Fischer-Tropsch synthesis, in drug-delivery applications, in magnetic resonance imaging (MRI) and in treating hyperthermia (Huber 2005). Iron nanoparticles
have been used to remediate industrial sites that were contaminated with chlorinated
organic compounds (Zhang 2003) (Table 2). Platinum nanoparticles exhibit antioxidant properties, but what applications they are to be put to is as yet undeciphered.
Although no applications have yet emerged, it is interesting to note that platinum
NPs have antioxidant activity that increases roundworm longevity (Kim et al. 2008;
Table 2). The total market for nanoparticles in biotechnology, drug discovery and
development was valued at $17.5 billion in 2011. The value is predicted to reach
approximately $53.5 billion in 2017 (BCC Research 2012).
The commercially important metal oxide nanomaterials include TiO2, ZnO,
Fe2O3, Fe3O4, SiO2, MgO and Al2O3. These nanomaterials increasingly have applications as catalytic devices, sensors, uses in environmental remediation and in


8

D. Soni et al.

Table 2 A summary of the major applications for engineered nanoparticles
Nanoparticle

Carbon -based
nanoparticle
a.Fullerene

b. CNT (SWNT
and MWNT)
Metal nanoparticles
a. Gold

b.Silver

c.Iron

d.Platinum
Metal oxide
nanoparticles
a.Magnesium
oxide
b.TiO2

c.ZnO
d. Iron oxide

Quantum dots

Applications

Reference

a. Organic photovoltaics, antioxidants,

catalysts, polymers, water purification
and biohazard protective agents
b. Electronics and polymer industry,
batteries

a. Yadav and Kumar (2008)

a. Medical field and biological probe

b. As disinfectant in medical field,
cosmetics, water purifiers, plastic
wares, textiles.
c. Magnetic recording media, magnetic
tapes, catalysts, drug delivery,
remediation of contaminated sites.
d.Antioxidant

a. As scrubber for air pollutant gases
(CO2, NOx, SOx), sensors and catalysts
b. Photo catalyst, in photovoltaic
devices, cosmetics, paintings,
electronic devices and sensors.
c. UV blocker in sunscreens, sensors,
non linear optical systems
d. Ferrofluids, rotary shaft sealing,
loudspeakers, computer hard drives
and in magnetic resonant imaging.
Biomedical imaging, targeting specific
cell membrane receptors, cellular
biomolecules such as peroxisomes and

DNA and electronic industries

b. Koehler et al. (2008)

a. Gibson et al. (2007),
Horisberger and Rosset
(1977), Qian et al. (2008),
Tsai et al. (2007)
b. Chopra (2007), Li et al.
(2010)
c. Huber (2005), Zhang
(2003)
d. Kim et al. (2008)

a. Rodríguez and FernándezGarcía (2007)
b. Foller (1978)

c. Forzatti (2000), Wang
(2004)
d. Raj and Moskowitz (1990)

Alivisatos (2004), Chan et al.
(2002), Colton et al. (2004),
Dubertret et al. (2002), Lidke
et al. (2004), Wu et al. (2004)

different commercial products like cosmetics, sunscreens, textiles, paints, varnishes
and household appliances (Rodríguez and Fernández-García 2007). In Table 2, we
summarize the major applications to which metal oxide nanoparticles have been
put. Some metal oxide nanoparticles like MgO, TiO2, CaO and BaO are used as

scrubber material for gaseous pollutants (e.g., CO2, NOx, SOx) in the chemical
industry and as a catalyst support (Foller 1978; Forzatti 2000; Schmitz and Baird
2002). ZnO nanoparticles exhibit multiple novel nanostructures like nanorings,
nanohelics, nanosprings, which are not observed in other types of oxide nanoparticles (Wu et al. 2007) (Table 2). Wang (2004) suggested future applications for ZnO


Release, Transport and Toxicity of Engineered Nanoparticles

9

in gas sensors, solar cells and non-linear optical systems. Iron oxide nanoparticles
like FeO (Iron oxide), Fe3O4 (Magnetite), α-Fe2O3 (Hematite) and γ-Fe2O3
(Maghemite) occur naturally. These are found in bacteria, insects, weathered soils,
rocks, natural atmosphere and polluted aerosols (Cornell and Schwertmann 1996).
Magnetite and maghemite minerals are used in different sectors owing to their magnetic properties as ferrofluids (Raj and Moskowitz 1990) (Table 2). Fe3O4 nanoparticles have received regulatory approval as an antibacterial agent and can be applied
to limit bacterial growth (Ramteke et al. 2010).
Nanomaterials made of fluorescent semiconductor nanocrystals (~2–100 nm)
have electronic properties between those of bulk semiconductors and discrete molecules, and are referred to as Quantum dots (QDs) (Brus 2007). Such nanomaterials
include CdTe (cadmium telluride), CdSe/ZnS (cadmium selenide/zinc sulphide),
CdSe (cadmium selenide), PbSe (lead selenide) and InP (indium phosphide). These
QDs materials have certain sought-after properties that include a narrow emission
band, wide excitation wavelength and photo stability. These properties qualify QDs
as a candidate for applications in biomedical imaging, specific cell membrane
receptor targeting (Alivisatos 2004; Chan et al. 2002; Lidke et al. 2004), and use
with cellular biomolecules such as peroxisomes (Colton et al. 2004) and DNA
(Dubertret et al. 2002) (Table 2). QDs are used currently in the manufacture of
advanced flat panel LED displays, and are expected to be used for ultrahigh-density
data storage and quantum information processing (Wu et al. 2004). Hence, it is clear
that the ENPs are rapidly gaining wider application in consumer products and in the
industrial sector. As a consequence of their growing popularity, production and

application, environmental releases of ENPs will increase.

3  R
 elease Pathways of Engineered Nanoparticles
in the Environment
As for other metal or organic pollutants, nanoparticles are either intentionally or
accidentally released, and come from either point or non-point sources (Fig. 2). Point
or stationary sources include production facilities and wastewater treatment plants.
Treatment plants are major potential sources of release for nanoparticles. As occurs
with other inorganic or organic pollutants that are concentrated for treatment in water
treatment plants, nanoparticles may interact with organic and inorganic matter to
form complexes, or new compounds (Pandey and Kumar 1990). Thus, nanoparticles
may be retained and interact with other environmental constituents after passing
through treatment procedures. Gottschalk et al. (2009) predicted significant environmental concentrations of nano- TiO2, ZnO, CNT, Ag and fullerene in USs, European
and Swiss treated plant effluents. The concentrations of such released nanoparticles
tend to be in the ng/L range. Moreover, these authors expect potential risks to aquatic
organisms from release of Ag, TiO2 and ZnO nanoparticles (Gottschalk et al. 2009).
Nonpoint source releases may occur from leaching or “wear” of nanomaterialcontaining products like paints, varnishes, cosmetics, and cleaning agents that are


10

D. Soni et al.

Transport of
nonoparticles

Cream Spray

Industry

(Nanoparticle
synthesis)

Applications of
nanoparticles
Life cycle and
release of
nanoparticles in
environment

Clothes

Release of
nonoparticles in
environment

Exposure of
nanoparticles to
living organisms

Release of
nonoparticles in
aquatic system

Paint

Air
Water

Soil

Fig. 2  Schematic diagram depicting the engineered nanoparticle life cycle, including use, release,
transport, and ultimate environmental exposures

disposed of or released to soil or surface water (Biswas and Wu 2005). Accidental
release may occur during the production or transportation of nanomaterial-­containing
products. Some nanomaterials are intentionally released into the environment, e.g.,
for remediation of ground- and waste-water (Nowack and Bucheli 2007). It is
becoming necessary that both scientists and regulators do more to understand the
different routes by which nanoparticles are released to the different environmental
compartments, i.e., air, water and soil.
Nanomaterials are released to air mainly via use of aerosol products, vehicle
emissions of gases containing nanoparticles, manufacturing and production discharges, consumer product aerosols, and release of industrial soot and smoke. It has
been reported that vehicle exhaust produces aerosol concentration ranges from 104
to 106 particles per cm3, with most nanoparticles in the size ranges below 50 nm
diameter (Biswas and Wu 2005).
In Table 3 we summarize literature studies that were undertaken to evaluate
nanoparticle releases to the atmosphere.
Nanoparticles that are released to aquatic systems may result from land run-off,
and industrial and household wastewater effluents; moreover, a major source is metalbased nanoparticle use for water remediation (e.g., zero-valent iron nanoparticles)
(Defra 2007; Vaseashta et al. 2007). Kaegi et al. (2008) has shown that TiO2 nanoparticles present in building paints (whitening pigments) are shed and then released to


11

Release, Transport and Toxicity of Engineered Nanoparticles

Table 3  A summary of studies in which the release of nanoparticles to the atmosphere has been
addressed
Study done

Release from the handling of surface
coatings
Release of CNTs during the disposal
of lithium-ion secondary batteries and
synthetic textiles, in landfills or
dumpsites or by lower temperature
incineration.
Release from gas-stoves, electric
stoves and electric toasters

62 printers tested for nanoparticles
release
Indoor and outdoor environment
nanoparticles coming from soot of
candle, wood or other cooking species
and diesel soot, soot from fires.
1999–2001 study conducted in Madrid
and Mexico city for the presence of
polycyclic aromatic hydrocarbons on the
surface and the total active surface area
of nanoparticles present on the road.
PM10 and PM2.5 mass concentration
study at 31 sites in Europe
Urban and suburban aerosol levels
looking at the effects of seasonal
variation, wind speed, traffic density
and temperature
Study in southwest Detroit to establish
ultrafine number concentrations and
size distribution.

21 days study at two major road sides
of EI Paso, USA

Results obtained
No significant released concentration
of <100 nm was detected
Observed release as dust particles
of CNT.

Reference
Vorbau et al.
(2009)
Koehler
et al. (2008)

High concentrations of particles with
average diameter of 5 nm were found
from gas and electric stove, which
quickly coagulate.
40% emission of PM-2.5 with particle
size range of 7–500 nm
Most includes aggregates of
carbonaceous and MWNT, silica
and concentric fullerene.

Wallace
et al. (2008)

Observe reduction in both
measurements.

Siegmann
et al. (2008)

Increased concentrations observed
during morning hours, relating to
increased traffic.
90% of nanoparticles are found in urban
areas and 70–80% in suburban areas

Dingenen
et al. (2004)

Major sources of ultrafines were
concluded to be from fossil fuel
combustion and atmospheric gas-toparticle conversion of precursor gases
Mean average particle concentrations
noted to be 13,600 and 14,600 cm−3

Young and
Keeler
(2004)

He et al.
(2007)
Murr and
Garza (2009)

Hussein
et al. (2005)

Noble et al.
(2003)

surface water via atmospheric precipitation. Nanoclusters and polynuclear complexes
of aluminium (Al13 or Al30) (Casey et al. 2001; Furrer et al. 2002) and sulfides (Cu4S6)
(Luther and Rickard 2005) were reported to exist in natural water. Infiltration is the
major source of ground water recharge and is through which nanomaterials enter
ground water (Greg 2004).
Nanomaterials are applied to remediate soil and water pollutants (Waychunas
et al. 2005; Yue and Economy 2005). In the near future, it is expected that wastes
from the nano-industry that are treated by municipalities and cities will be released
in plant effluents (Blaise et al. 2008).


12

D. Soni et al.

4  F
 ate and Transport of Engineered Nanoparticles
in the Environment
After ENPs are released to the environment, they may remain as they are, or their
makeup and character may be altered by the action of the environment. Their surface characteristics, structure and reactivity may be altered during transport into or
within the environment. Moreover, the physico-chemical characteristics (e.g., pH,
ionic strength, presence of organic matter) of various environmental media may
affect the transport of ENPs. Below we describe the studies that have been conducted to discover how ENPs move and are affected by environmental media.

4.1  Air
Madler and Friedlander (2007) described how nanoparticles are transported in air

(Table 4). They compared the transport of these very small entities (ENPs) as being
similar to how fluids are transported. In the absence of external forces, Brownian
diffusion is the main transport mechanism by which nanoparticles move in gaseous
atmospheres. Madler and Friedlander (2007) derived an equation of particle diffusivity (D) that is given as follows:
x 2 u2 t u2 m κ T
=
=
=
2t β t
ζ
ζ

Where D is particle diffusivity, x is direction coordinate, t is time, u is velocity, m is
mass of the particle, ζ is the friction coefficient, κ is Boltzmann constant and T is the
translational energy of a gas molecule. As described by this equation, particle transport is related to the frictional coefficient that depends on drag force and velocity
between particle and fluid. However, this relation may not be accurate for determining particle diffusivity through air.
D=

Table 4  Factors that facilitate the transport of ENPs in ecosystems
Ecosystem
Air (Abiotic
interaction)

Water

Soil

Behavior of nanoparticles
a.Diffusion
b. Brownian coagulation

c.Agglomeration
a.Aggregation
b. Interaction with natural organic matter
c.Adsorption
a. Depend on charge
b.Aggregation
c. Interaction with organic molecules
d. Degradation and surface modification

Reference
a. Friedlander (2000), Madler
and Friedlander (2007)
b. Lall and Friedlander (2006)
c. Bandyopadhyaya et al. (2004)
a. Guzman et al. (2006)
b. Ghosh et al. (2008)
c. Keller et al. (2010)
a. Darlington et al. (2009)
b. Solovitch et al. (2010)
c. Jaisi and Elimelech (2009)
d. Navarro et al. (2011)


Release, Transport and Toxicity of Engineered Nanoparticles

13

Brownian diffusion leads to dispersion of particles into the air. Dispersion may
also occur from mechanical mixing during industrial processes, interfacial instability between immiscible layers of solvents and differences in molecular structures of
particles. A velocity-based model describes the spreading of a solute in time and

space. The convection-dispersion equation (CDE) for dispersion of non-reactive
solute can be given as:
∂C
∂C
∂ 2C
= K 2 −v
∂
t
∂x
∂
x

Where C is the concentration of solute, t is time, x is distance, K is the diffusion-­
dispersion coefficient and v is the mean velocity. This equation predicts that the K
and v do not vary in space or with direction. K and v are related to the mean and
variance of the normal distribution of distances traversed by the solute (Perfect and
Sukop 2001).
Another ENP transport mechanism in air is via agglomeration. Herein, individual particles agglomerate through Brownian motion and collide, leading to increased
size. The small size of nanoparticles makes them unstable and thus assists their collision with each other. Repeated collisions form particle agglomerates
(Bandyopadhyaya et al. 2004). Nanoparticle agglomerates may collide with the
molecules of surrounding gas (Lall and Friedlander 2006) (Table 4). Friedlander
(2000) suggested that Brownian movement was responsible for the highest collision
rates of nanoparticles and was more influential than other transport mechanisms
such as turbulent flow (Table 4). Friedlander described the fractal nature of ENPs
agglomerates mathematically as:



 Rg 
Np = Kf 

D
 d / 2  f
 p 

Where, Np is the number of primary particles that forms agglomerates, dp is
diameter of particles, Kf is fractal prefactor, Rg is radius of gyration (mean root
square of the distances between the spherules and the centre of mass of the agglomerate) and Df is fractal dimension. The above mentioned equation can be used to
estimate the number of ENPs undergoing agglomeration.
The physico-chemical characteristics of ENPs affect their fate as does how they
are transported in air. Lowry et al. (2012) reported the possible mechanisms by which
nanoparticles behave and are transformed in the environment Aitken et al. (2004)
reported that particles having diameters ≤100 nm remain suspended in air for longer
times and are capable of diffusing. Particle size bears an inverse relationship with
diffusion rate, whereas gravitational settling is directly proportional. ENPs have been
classified by their sizes and behavior, when present in the atmosphere. Small particles
(<80 nm) tend to be short lived and to agglomerate. Large particles (>2,000 nm) are
coarse and are subjected to gravitational settling or sedimentation. Particles of intermediate size (>80 nm and <2,000 nm) persist for longer periods in the atmosphere
(http www epa gov osa pdfs nanotech epa nanotechnology whitepaper 0207 pdf).