5
intentional, nonpoint source, accidental, and point source. All four methods by
which nanoparticles are inadvertently released result in them being absorbed by
the environment and humans, either through the soil where agricultural crops are
grown or through groundwater contamination.Intentional release is a designed
method of deliberately releasing nanoparticles into the ecosystem for the purpose of biodegradation and absorption by the environment. Here, nanoparticles
are released into water or soil, causing them to interact or diffuse with other
molecules, which is referred to as nanoparticle aggregate diffusion. The contaminated molecules then seep into groundwater, which is inadvertently consumed by
animal and plant species as well as humans in the area. Aggregation kinetics is
essential in the disposal methodology of nanoparticle aggregates and can be
studied by the nanoparticle mass (N) and fractal dimensions d f using molecular
dynamic simulation software, such as LAMMPS, Desmond, GROMOS, or
Materials Studio, in the presence of solvent molecules. Through simulation, the
diffusion coefficient (D o ) for the aggregates can be determined to scale D o α N
-df
(Fraaije et al. 2018).
Nonpoint source release occurs when contaminants are released into the environment over an extensive area. These are some examples (Huang et al. 2008):
Air: When a car is running, the engine produces a variety of chemical products, including
oxides of nitrogen (some of which are toxic) and molecules of unburned hydrocarbons from
gasoline. Similarly, in industrial areas, pollutants and soot are caused from combustion
processes such as burning.
Water: As the result of nanomaterials being released into the environment, acid rain can
form, changing the pH balance of the water, which can enter the water cycle. The result can
be catastrophic to the ecosystem, harming the fish populous and other creatures that depend
on freshwater lakes and streams.
Soil: Hazardous nanomaterials can enter the soil from the air or water, thereby changing the
soil due to the absorption of the nanomaterial. Occasionally, these nanoparticles are
absorbed by plants, which in turn causes the plants to become toxic.
The accidental release of nanomaterials occurs during production or in factories
by means of human error or through the waste stream, although environmental regulations have been put in place to ultimately limit this type of release.
Point source release of nanomaterials has been defined by the U.S. Environmental
Protection Agency as any single detectable source from which pollutants are
released, such as a ditch, pipe, ship, or factory flue gas stack (NOAA 2017). From
knowledge of the nanomaterial being released in this manner, the U.S. Environmental
Protection Agency can regulate the amount that is released and can try to hold companies responsible for this waste. However, unregulated release of nanomaterials
from point sources can have considerable consequences, resulting in water pollution
and unsafe drinking water, as well as restricting activities such as fishing, water
sports, and swimming in these areas. Some of the chemicals released by point
sources have been identified as harmless, but others have been noticed to be highly
toxic to the ecosystem, humans, and wildlife. Whether the release of a chemical is
harmful to the ecosystem in surrounding areas depends on numerous factors such as
1 Nanotoxicity and Nanoecotoxicity: Introduction, Principles, and Concepts
intentional, nonpoint source, accidental, and point source. All four methods by
which nanoparticles are inadvertently released result in them being absorbed by
the environment and humans, either through the soil where agricultural crops are
grown or through groundwater contamination.Intentional release is a designed
method of deliberately releasing nanoparticles into the ecosystem for the purpose of biodegradation and absorption by the environment. Here, nanoparticles
are released into water or soil, causing them to interact or diffuse with other
molecules, which is referred to as nanoparticle aggregate diffusion. The contaminated molecules then seep into groundwater, which is inadvertently consumed by
animal and plant species as well as humans in the area. Aggregation kinetics is
essential in the disposal methodology of nanoparticle aggregates and can be
studied by the nanoparticle mass (N) and fractal dimensions d f using molecular
dynamic simulation software, such as LAMMPS, Desmond, GROMOS, or
Materials Studio, in the presence of solvent molecules. Through simulation, the
diffusion coefficient (D o ) for the aggregates can be determined to scale D o α N
-df
(Fraaije et al. 2018).
Nonpoint source release occurs when contaminants are released into the environment over an extensive area. These are some examples (Huang et al. 2008):
Air: When a car is running, the engine produces a variety of chemical products, including
oxides of nitrogen (some of which are toxic) and molecules of unburned hydrocarbons from
gasoline. Similarly, in industrial areas, pollutants and soot are caused from combustion
processes such as burning.
Water: As the result of nanomaterials being released into the environment, acid rain can
form, changing the pH balance of the water, which can enter the water cycle. The result can
be catastrophic to the ecosystem, harming the fish populous and other creatures that depend
on freshwater lakes and streams.
Soil: Hazardous nanomaterials can enter the soil from the air or water, thereby changing the
soil due to the absorption of the nanomaterial. Occasionally, these nanoparticles are
absorbed by plants, which in turn causes the plants to become toxic.
The accidental release of nanomaterials occurs during production or in factories
by means of human error or through the waste stream, although environmental regulations have been put in place to ultimately limit this type of release.
Point source release of nanomaterials has been defined by the U.S. Environmental
Protection Agency as any single detectable source from which pollutants are
released, such as a ditch, pipe, ship, or factory flue gas stack (NOAA 2017). From
knowledge of the nanomaterial being released in this manner, the U.S. Environmental
Protection Agency can regulate the amount that is released and can try to hold companies responsible for this waste. However, unregulated release of nanomaterials
from point sources can have considerable consequences, resulting in water pollution
and unsafe drinking water, as well as restricting activities such as fishing, water
sports, and swimming in these areas. Some of the chemicals released by point
sources have been identified as harmless, but others have been noticed to be highly
toxic to the ecosystem, humans, and wildlife. Whether the release of a chemical is
harmful to the ecosystem in surrounding areas depends on numerous factors such as
1 Nanotoxicity and Nanoecotoxicity: Introduction, Principles, and Concepts