Environmental Engineering Reference
In-Depth Information
Mulleretal.(
2005
) studied the effect of intratracheally administered MWNTs
(doses:0.5,2,or5mg)inSprague-Dawleyrats.TheMWNTspersistedinthelung
and caused inflammation and fibrosis. Further, NPs persisted in lung tissues have
been examined biochemically and histologically after a period of 60 days. Results
indicated that both inflammatory and fibrotic reactions were induced by the treat-
mentsMulleretal.(
2005
)(Table
5
).Warheitetal.(
2004
) conducted a similar study
withSWNTsinratsat1-5mg/kg,andfoundthattheSWNTsproducedtransient
inlammationandcellinjury.
Gastrointestinaldosing(at5g/kgbodywt)inmice(Wangetal.
2006
), with either
nano-zinc oxide or larger particles resulted in more severe symptoms being pro-
duced by the nano-treated group. The symptoms included lethargy, vomiting, diar-
rhea,anddeathsfromintestinalobstructionbyaggregatednano-zincoxide(Table
5
)
(Wangetal.
2006
). A significant decrease in lung function was observed by Conner
etal.(
1985
)inguineapigsthathadinhaled6mg/m
3
ofnanozincoxideparticles
(50nm),alongwith1ppmofsulphurdioxidefor3hdailyforsixconsecutivedays.
The effects of ENPs on human beings have yet to be studied. It is presumed that
some insight to how ENPs affect humans may eventually be gleaned from occupa-
tional exposures or exposures to certain pollutants that have a NP character. Xia
etal.(
2009
)predictedthatreactiveoxygenspecies(ROS)andoxidativestressmay
be generated by inhalation of ultrafine particles and may lead to respiratory and
cardiovascular inflammation. For instance, occupational exposure of miners in cen-
tral India to manganese during mining operations revealed a genetic polymorphism
incytochromeP4502D6(CYP2D6*2),glutathione-S-transferaseM1(GSTM1)and
NAD(P)Hquinineoxidoreductase1(NQO1)genes(Vinayagamoorthyetal.
2010
).
5.3
Plants
The toxicity of nanoparticles to terrestrial plants has been studied at different con-
centrations and under different conditions. In Table
6
, we summarise the effects that
ENPs have had on different plant species.
Khodavskayaetal.(
2009
)testedCNTsintomatoseedsatlevelsof10-40ʼg/mL
and discovered that the seed coat was penetrated by the NPs, producing an increased
germinationrate.Wangetal.(
2011
)reportedtheeffectsoftreatingryegrass(
Lolium
perenne
)andpumpkin(
Cucurbita mixta
cv. white cushaw) with magnetite nanopar-
ticles(Fe
3
O
4
)atlevelsof30,100and500mg/L.TheseNPsinducedmoreoxidative
stressthandidtheirbulkcounterparts.Thisresultwasconirmedbymeasuringthe
activitiesofSOD,catalaseandlipidperoxidation(Table
6
).
Yang and Watts (
2005
) assayed the phytotoxicity of aluminium NPs (with or
without phenanthrene) during seed germination, root elongation and formation of
leaves in five plant species (corn, cucumber, soya bean, cabbage and carrot).
Exposure of aluminium NPs at a 2 mg/mL concentration after 24 h resulted in
stunted root growth.
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