Environmental Engineering Reference
In-Depth Information
It may also be inferred that at lower concentrations, ENPs will tend to show less aggre-
gation that may lead to greater uptake and response than expected at higher concen-
trations. However, different ways of stabilizing the ENPs (particle coating, dispersant/
surfactant, sonication) mitigate agglomeration, thereby resulting in an exacerbated biologi-
cal response. The stability of the ENPs inside the cell or aquatic environment as well as
their interaction with cellular metabolites on the ENPs are the other key issues that need
to be addressed to understand the adverse effects of ENPs. Other possible effects of ENP
uptake could be the interaction with other possibly toxic substances and their mobilization
and bioavailability.
The environmental fate, behavior, and bioavailability of ENPs are not well understood;
therefore, their persistence and the possible interaction and impact, particularly biomag-
niication in food webs, is an immediate concern [7]. Hence, to evaluate and assess the
effect of ENPs in an aquatic ecosystem, it is proposed that the study design should include
the interaction of the ENPs at the subcellular, cellular, and organism level (Figure 5.3). A
multipronged approach involving ENP characterization, uptake, biochemical studies, his-
topathology, genomics, proteomics, and metabolomics should be conducted to assess the
impact of ENPs at subcellular and cellular levels (Figure 5.3). However, for understanding
the effects at the organism level, the studies should be supplemented with life cycle and
reproduction studies.
The impurities in the ENP preparation also inluence the toxic outcomes; therefore, the
effects of these impurities should also be considered in the study design. Elemental analy-
sis using different techniques could help in analyzing these impurities [47]. Some of the
metal oxide nanoparticles are known to release ions in the aqueous suspension, which
could alter the toxicity. Hence, the quantiication of soluble metal ions in the exposure
medium is also a prerequisite in nanotoxicology studies [15,35,48]. Lack of reference mate-
rials, appropriate methods to monitor ENP behavior in various matrices, dose dilemma,
Approaches
Models
Uptake,
toxicity
Bacteria
Daphnia
Biochemical
studies
Eco-toxicity
Duckweed
Fecundity/
microcosm
mecocosms
ENPs
Tu bifex
Mechanism
of toxicity
Genomics
C. elegans
Proteomics
FIGURE 5.3
Aquatic toxicity of engineered nanoparticles: approaches and models.
