305
2006). Most metal oxide nanoparticles show genotoxic and cytotoxic properties on
fish cells (Handy et al. 2008; Vevers and Jha 2008). In the presence of magnetic
nanoparticles of <10 nm dimension, neuronal cells enter a latent state and stop to
react to chemical signals (Johnson 2007). Fullerenes are also reported to kill liver,
skin and brain cells in vitro (Lewinski et al. 2008). Those nanoparticles which have
been degraded in the cellular milieu could build up intracellularly, leading to either
gene modification(s) or destruction of organelle integrity. Carbon-, metal-, and
semiconductor-based nanoparticles, at high doses, exert cellular toxicity effects in a
dose- and time-dependent manner. In case of reproductive system, literature cited
works suggest that nanoparticles accumulate in the testes by traversing the blood–
testes barrier and exert damage on sperm cells (McAuliffe and Perry 2007).
11.8 Risk Assessment of Engineered Nanoparticles
Repeated release as well as contact of ENPs with many elements of environment
and trophic levels and likely hazards call for the strategy development or set patterns
to test the probable risks of engineered nanomaterials. The toxicity of engineered
nanomaterials is dependent upon their basic physicochemical properties and added
functional chemico-biological features. Thus, these basic properties need to be evaluated while investing their probable ecological toxicity that becomes difficult
because (i) their actual concentration in environment is much less than the measurable limits for most experimental tests and (ii) in addition to intentional ENPs, environment also consists of naturally produced NPs (Lead and Wilkinson 2006).
Therefore, development/updating of currently available system to attain an improved
screening potential and high selective recognition are the prerequisite. The first step
toward this is pre-fractionation, that is, reduction of the mixture of particles in the
real samples using stirring, centrifugation, or filtration. Size fractionation can be
achieved through membranes (ultrafiltration, nanofiltration, and dialysis) as well as
chromatography (Hassellöv et al. 2008). After that the size of ENPs can be examined through several instrumentations, light scattering is a frequently used method.
Post analysis and characterization of ENPs, both the short- and long-term effects of
ENPs on living organisms are tested. Establishment of a dose–response relationship
by subjecting the organism to varying concentrations of NPs is a common pattern in
almost all nanotoxicity-related studies (Navarro et al. 2008). The environmental
hazards associated with chemical substances are assessed through standard ecotoxicity tests that focuses on the target/nontarget test species, endpoints protocols and
measurement. The standard endpoints that are calculated [for example, lethal concentrations (LC), effective concentrations (EC) or no observed effect concentrations
(NOECs)] are usually for higher organisms. In case of microbes and algae, the endpoint is population growth because of their fast growth (Crane and Scott 2012).
11 Environmental Impact and Econanotoxicity of Engineered Nanomaterials
2006). Most metal oxide nanoparticles show genotoxic and cytotoxic properties on
fish cells (Handy et al. 2008; Vevers and Jha 2008). In the presence of magnetic
nanoparticles of <10 nm dimension, neuronal cells enter a latent state and stop to
react to chemical signals (Johnson 2007). Fullerenes are also reported to kill liver,
skin and brain cells in vitro (Lewinski et al. 2008). Those nanoparticles which have
been degraded in the cellular milieu could build up intracellularly, leading to either
gene modification(s) or destruction of organelle integrity. Carbon-, metal-, and
semiconductor-based nanoparticles, at high doses, exert cellular toxicity effects in a
dose- and time-dependent manner. In case of reproductive system, literature cited
works suggest that nanoparticles accumulate in the testes by traversing the blood–
testes barrier and exert damage on sperm cells (McAuliffe and Perry 2007).
11.8 Risk Assessment of Engineered Nanoparticles
Repeated release as well as contact of ENPs with many elements of environment
and trophic levels and likely hazards call for the strategy development or set patterns
to test the probable risks of engineered nanomaterials. The toxicity of engineered
nanomaterials is dependent upon their basic physicochemical properties and added
functional chemico-biological features. Thus, these basic properties need to be evaluated while investing their probable ecological toxicity that becomes difficult
because (i) their actual concentration in environment is much less than the measurable limits for most experimental tests and (ii) in addition to intentional ENPs, environment also consists of naturally produced NPs (Lead and Wilkinson 2006).
Therefore, development/updating of currently available system to attain an improved
screening potential and high selective recognition are the prerequisite. The first step
toward this is pre-fractionation, that is, reduction of the mixture of particles in the
real samples using stirring, centrifugation, or filtration. Size fractionation can be
achieved through membranes (ultrafiltration, nanofiltration, and dialysis) as well as
chromatography (Hassellöv et al. 2008). After that the size of ENPs can be examined through several instrumentations, light scattering is a frequently used method.
Post analysis and characterization of ENPs, both the short- and long-term effects of
ENPs on living organisms are tested. Establishment of a dose–response relationship
by subjecting the organism to varying concentrations of NPs is a common pattern in
almost all nanotoxicity-related studies (Navarro et al. 2008). The environmental
hazards associated with chemical substances are assessed through standard ecotoxicity tests that focuses on the target/nontarget test species, endpoints protocols and
measurement. The standard endpoints that are calculated [for example, lethal concentrations (LC), effective concentrations (EC) or no observed effect concentrations
(NOECs)] are usually for higher organisms. In case of microbes and algae, the endpoint is population growth because of their fast growth (Crane and Scott 2012).
11 Environmental Impact and Econanotoxicity of Engineered Nanomaterials