• OECD TG 217—carbon transformation test (OECD 2000b): similar modifications are proposed for this test, except the multiple short-term measurements.
28.4.2 Fe-Based Nanoparticles Exempt from Nano-Fear
nZVI and Fe-oxide-based nanoparticles have, to some extent, dodged the skepticism
that clings to other types of nanoparticles. This is partly because nanoparticles for
remediation are used to treat and remove the harmful effects of toxic pollutants, thus
reducing the exposure of humans and the environment to highly toxic and mobile
chemicals like TCE (trichloroethylene) for which there are no doubts of adverse
effects or environmental exposure. Further, Fe-based nanoparticles have repeatedly
been shown to have limited or even very limited mobility in the environment,
restricting movement away from the treated areas (Johnson et al. 2013), which are
often fenced in and unavailable to the public. Thus, risks appear confined to the
treated areas. A third point in favor of Fe-based nanoparticles comes from the fact
that most natural environments contain ample amounts of Fe, even in forms similar
to those coming out of nanoremediation treatments. The products of nZVI aged in
aerated water are mainly Fe 3 O 4 (magnetite) and γ-Fe 2 O 3 (maghemite), accompanied
by γ-FeOOH (goethite). If corrosion continues, the products are predominantly
γ-FeOOH, with small amounts of Fe 3 O 4 and γ-Fe 2 O 3 (Liu et al. 2015). The final
aqueous corrosion product of nZVI is FeOOH (Pullin et al. 2017; Lei et al. 2018).
Finally, Fe-based nanoparticles have been scrutinized in several research projects in
parallel to their development, and the outcome of the ecotoxicity measurements as
well as practitioners feedbacks indicate that Fe-based nanoparticles are causing low
concern, if any (Bardos et al. 2011; Hjorth et al. 2017).
28.4.3 Ecotoxicity Does Not Equal Risk
Risk is the product of hazard (ecotoxicity) multiplied by the probability of encountering hazard (exposure). As mobility of nZVI and other Fe-based nanoparticles is
limited, and as their prescribed use targets subsoils at several meters depth in
industrial brownfields, the risk to humans (apart from workers exposed during
production, transport, and deployment) and wildlife is extremely low or inexistent.
The low hazard level due to the low inherent toxicity of the Fe-based nanomaterials
of course also contributes to the low risks.
582
C. Coutris et al.
28.4.2 Fe-Based Nanoparticles Exempt from Nano-Fear
nZVI and Fe-oxide-based nanoparticles have, to some extent, dodged the skepticism
that clings to other types of nanoparticles. This is partly because nanoparticles for
remediation are used to treat and remove the harmful effects of toxic pollutants, thus
reducing the exposure of humans and the environment to highly toxic and mobile
chemicals like TCE (trichloroethylene) for which there are no doubts of adverse
effects or environmental exposure. Further, Fe-based nanoparticles have repeatedly
been shown to have limited or even very limited mobility in the environment,
restricting movement away from the treated areas (Johnson et al. 2013), which are
often fenced in and unavailable to the public. Thus, risks appear confined to the
treated areas. A third point in favor of Fe-based nanoparticles comes from the fact
that most natural environments contain ample amounts of Fe, even in forms similar
to those coming out of nanoremediation treatments. The products of nZVI aged in
aerated water are mainly Fe 3 O 4 (magnetite) and γ-Fe 2 O 3 (maghemite), accompanied
by γ-FeOOH (goethite). If corrosion continues, the products are predominantly
γ-FeOOH, with small amounts of Fe 3 O 4 and γ-Fe 2 O 3 (Liu et al. 2015). The final
aqueous corrosion product of nZVI is FeOOH (Pullin et al. 2017; Lei et al. 2018).
Finally, Fe-based nanoparticles have been scrutinized in several research projects in
parallel to their development, and the outcome of the ecotoxicity measurements as
well as practitioners feedbacks indicate that Fe-based nanoparticles are causing low
concern, if any (Bardos et al. 2011; Hjorth et al. 2017).
28.4.3 Ecotoxicity Does Not Equal Risk
Risk is the product of hazard (ecotoxicity) multiplied by the probability of encountering hazard (exposure). As mobility of nZVI and other Fe-based nanoparticles is
limited, and as their prescribed use targets subsoils at several meters depth in
industrial brownfields, the risk to humans (apart from workers exposed during
production, transport, and deployment) and wildlife is extremely low or inexistent.
The low hazard level due to the low inherent toxicity of the Fe-based nanomaterials
of course also contributes to the low risks.
582
C. Coutris et al.