173
the major sink of anthropogenic contaminants. Thus, investigations focusing on the
route of nanomaterials release and their effects on the aquatic biota are of paramount importance (Griffitt et al. 2012) for risk assessment purposes.
Considering the various nanomaterials’ physicochemical properties and abiotic
factors that influence their ecotoxicity, both spatially and over time, there is still a
gap of knowledge between nanotoxicological research and nanomaterial safety that
must be accomplished. There is variability in toxic effects of nanomaterials that
depends on the aquatic organism, exposition time, and route used to prepare the
materials. Bioavailability is influenced by water quality parameters and nanomaterial formulation. Once available in the aquatic environment, nanomaterials can be
affected by their surroundings and undergo transformations by three major phenomena: dissolution, organism-dependent cellular uptake, and promotion of oxidative
stress and consequent cellular damages (Ivask et al. 2014). Reactive oxygen species
(ROS) can induce oxidative stress resulting in cyto- and genotoxicity and trigger the
induction of antioxidant enzymes that are used as response biomarkers (Vale et al.
2016). Although oxidative stress can be a driver for many nanoparticle-induced
effects, nanoparticles have the ability to act via multiple pathways (Bundschuh
et al. 2018).
The dispersion stability of nanomaterials can influence their environmental fate
by defining dissolution rate/surface reactivity, effective size, and long-range transport (Monikh et al. 2018). Surface-functionalized particles can limit or inhibit environmental transformations, which influence particle aggregation, mobility,
dissolution, and ecotoxic potential (Shevlin et al. 2018). In addition, contaminants
as micro-pollutants with different chemical properties can interact with several
types of nanoparticles. For example, carbon nanomaterials can synergistically and/
or antagonistically interact with these contaminants.
The consideration of the effect assessment at different trophic levels is necessary
in order to evaluate with more accuracy the probability of adverse effects and to
determine safe concentrations in the aquatic compartments (USEPA 1994). In order
to establish such concentration limits, toxicity studies in at least three trophic levels
are necessary: one primary producer (e.g., algae), one primary consumer (e.g.,
microcrustaceans), and one secondary consumer (e.g., fish) (European Commission
2003), which are important sources of food for larger animals (Suthers and Rissik
2009). The species-sensitivity distribution (SSD) method can provide a reliable statistics for the determinations of safe concentrations of nanomaterials. This approach
is based on an recognized distribution of a toxicity data set obtained from different
species, including algae and invertebrates among other aquatic organisms (Lei et al.
2012; Garner et al. 2015; Castro et al. 2018). In this context, this book chapter
reviews on some syntheses methods employed for producing varied engineered
nanoparticles, including silver nanoparticles, carbon nanotubes, zinc oxide nanoparticles, copper oxide, graphene-based materials, and hydroxyapatite nanoparticles
and illustrates some examples of how the shape and functionalization of such
nanoparticles can influence their toxicity toward microalgae, microcrustaceans,
and fishes.
7 Toxicity of Engineered Nanostructures in Aquatic Environments
the major sink of anthropogenic contaminants. Thus, investigations focusing on the
route of nanomaterials release and their effects on the aquatic biota are of paramount importance (Griffitt et al. 2012) for risk assessment purposes.
Considering the various nanomaterials’ physicochemical properties and abiotic
factors that influence their ecotoxicity, both spatially and over time, there is still a
gap of knowledge between nanotoxicological research and nanomaterial safety that
must be accomplished. There is variability in toxic effects of nanomaterials that
depends on the aquatic organism, exposition time, and route used to prepare the
materials. Bioavailability is influenced by water quality parameters and nanomaterial formulation. Once available in the aquatic environment, nanomaterials can be
affected by their surroundings and undergo transformations by three major phenomena: dissolution, organism-dependent cellular uptake, and promotion of oxidative
stress and consequent cellular damages (Ivask et al. 2014). Reactive oxygen species
(ROS) can induce oxidative stress resulting in cyto- and genotoxicity and trigger the
induction of antioxidant enzymes that are used as response biomarkers (Vale et al.
2016). Although oxidative stress can be a driver for many nanoparticle-induced
effects, nanoparticles have the ability to act via multiple pathways (Bundschuh
et al. 2018).
The dispersion stability of nanomaterials can influence their environmental fate
by defining dissolution rate/surface reactivity, effective size, and long-range transport (Monikh et al. 2018). Surface-functionalized particles can limit or inhibit environmental transformations, which influence particle aggregation, mobility,
dissolution, and ecotoxic potential (Shevlin et al. 2018). In addition, contaminants
as micro-pollutants with different chemical properties can interact with several
types of nanoparticles. For example, carbon nanomaterials can synergistically and/
or antagonistically interact with these contaminants.
The consideration of the effect assessment at different trophic levels is necessary
in order to evaluate with more accuracy the probability of adverse effects and to
determine safe concentrations in the aquatic compartments (USEPA 1994). In order
to establish such concentration limits, toxicity studies in at least three trophic levels
are necessary: one primary producer (e.g., algae), one primary consumer (e.g.,
microcrustaceans), and one secondary consumer (e.g., fish) (European Commission
2003), which are important sources of food for larger animals (Suthers and Rissik
2009). The species-sensitivity distribution (SSD) method can provide a reliable statistics for the determinations of safe concentrations of nanomaterials. This approach
is based on an recognized distribution of a toxicity data set obtained from different
species, including algae and invertebrates among other aquatic organisms (Lei et al.
2012; Garner et al. 2015; Castro et al. 2018). In this context, this book chapter
reviews on some syntheses methods employed for producing varied engineered
nanoparticles, including silver nanoparticles, carbon nanotubes, zinc oxide nanoparticles, copper oxide, graphene-based materials, and hydroxyapatite nanoparticles
and illustrates some examples of how the shape and functionalization of such
nanoparticles can influence their toxicity toward microalgae, microcrustaceans,
and fishes.
7 Toxicity of Engineered Nanostructures in Aquatic Environments