Environmental Engineering Reference
In-Depth Information
Theresultwasadose-dependenttoxicityofAgNPsinzebraishembryos(Table
5
).
Nanoparticlesweredistributedinheart,brain,yolkandbloodofembryosasevi-
dencedbyTEMandelectrondispersiveX-rayanalysis(EDS).Phenotypicstudies
also revealed abnormal body axes, twisted notochord and slow blood flow.
In addition to acute toxicity studies, other studies have been performed to inves-
tigate the health and environmental impacts of NPs, by studying the changes in
expression levels of stress-related genes. One such study was conducted on Japanese
medakatoevaluatethetoxicityofsilvernanoparticleAgNPs.Heatshockprotein-70
(HSP70),p53,cytochromeP4501A(CYP1A)andtransferringgenewereselected
as stress markers. The mRNA concentrations were measured in liver extracts. In
addition to cellular and DNA damage, AgNPs caused oxidative stress and carcino-
genicity(Table
5
)(Chaeetal.
2009
). This study was extended to evaluate two addi-
tional biomarkers (metallothionein (MT), and glutathione S-transferase (GST)
gene) at an AgNP concentration of 1 ʼg/L in livers of exposed ish. The results
indicatedthatAgNPsarepotentialinducersofmetaldetoxiication,andoxidative/
inlammatorystress(Phametal.
2012
).
Fluorescent latex nanoparticles are absorbed into the chorion of see-through
medaka(
Oryzias latipes
)eggsandaccumulateinthegillsandintestine(Table
5
).
Nanoparticleshavealsobeenfoundinthebrain,testis,liverandbloodofmedaka
(
Oryzias latipes
). This study indicated that nanoparticles have the potential to pen-
etratetheblood-brainbarrier(Kashiwada
2006
).
5.2.3
Mammals
The toxicity of nanoparticles has been investigated in rats, mice and guinea pigs.
Roursguardetal.(
2008
)instilledfullerolNPs(doselevelspermouse:0.02,0.2,20
and 200 ʼg) and quartz (50 ʼg) intratracheally in mice and monitored responses
(Table
5
). The result was a dose-dependent neutrophil-induced lung inflammation in
thetreatedmice.Quartzinducedmoreinlammationthandidthefullerolnanopar-
ticles; in fact, inflammation in the presence of nanoparticles was minimal.
HandyandShaw(
2007
) performed respiratory studies in rats with carbon nano-
tubes(doses:0.1-12.5mg/kg),ultraineTiO
2
NPs(doses:0.5,2.0,10mg/L),ultra-
ine cadmium particles (70 ʼg/L), and metal oxide particles (1-5 mg) (Table
5
).
Results indicated significant lung damage, inflammation and fibrotic responses
when exposed to intra-tracheal doses of above-mentioned NPs (Handy and Shaw
2007
; Lam et al.
2004
).
Intraperitoneal injection of polyalkyl sulphonated C
60
produced toxicity due to
accumulationofthenanoparticlesinliver,spleenandkidneyofrats(Chenetal.
1998
).
Bullard-Dillard et al. (
1996
) studied the behavior and potential metabolism of
14
C-labelled C
60
in female Sprague-Dawley rats.
14
C
60
was cleared within 1 min
from blood and the majority of NPs were accumulated in the liver (90-95%).
Results of this study suggested that C
60
or its derivative may lead to long term
accumulationinliver(Table
5
).
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