Nanotoxicity - The Nanobiotechnology - page 614

exposure.(Zucker.et.al..2010,.Boyes.et.al..2011)..Fullerol.is.a.water-soluble.hydroxylated.fuller-
ene. that. proved. to. be. phototoxic. following. either. UVA. or. visible. light. exposure. (Roberts.
et.al..2008,.Wielgus.et.al..2010)..These.ocular.exposures.and.potential.damages.have.been.
ignored.in.many.nanotoxicological.researches.
27.4.4 reproductive System
The. reproductive. system. contains. delicately. controlled. mechanisms. for. maintaining. its.
physiological. functions. in. vivo.. In. the. male. and. female. reproductive. systems,. many. of.
the. interdependent. functions. are. vulnerable. to. interruption. by. exogenous. nanomateri-
als..In.1996,.Tsuchiya.et.al..(1996).found.that.fullerenes.intraperitoneally.administrated.to.
pregnant.mice.at.50.mg/kg.would.have.a.harmful.effect.on.both.conceptuses.by.micro-
scopic. evaluation.. Intranasal. chronic. exposure. to. carbon. black. nanoparticles. showed.
some.adverse. effects. on. the.male. reproductive. function.in. mice. (Yoshida. et.al.. 2009)..In.
addition,.soluble.carbon.nanotubes.have.potential.applications.in.nanobiotechnology.and.
nanomedicines.. It. has. been. shown. that. repeated. intravenous. injections. of. water-soluble.
MWCNTs. into. male. mice. could. cause. the. nanotubes. to. accumulate. in. the. testes,. which.
generated. oxidative. stress. and. decreased. the. thickness. of. the. seminiferous. epithelium.
in.the.testis..However,.the.nanotubes'.accumulation.led.to.reversible.testis.damage.with-
out.affecting.fertility..The.pregnancy.rate.and.delivery.success.of.female.mice.that.mated.
with.the.treated.male.mice.did.not.differ.from.those.controls.(Bai.et.al..2010)..Although.
it.seems.that.the.nanotubes.have.minor.effects.on.the.male.reproductive.system.in.mice,.
oxidative.stress.and.the.alterations.in.the.testes.raise.concerns.because.it.is.possible.that.
these.materials.may.accumulate.at.higher.quantities.over.a.longer.period.of.time.and.may.
have.more.serious.adverse.effects.on.male.fertility..There.is.direct.evidence.that.particles.
can.cross.the.placental.barrier.and.affect.the.fetus.(Wick.et.al..2010,.Yamashita.et.al..2011)..
Furthermore,.some.studies.have.shown.transplacental.transport.of.nanomaterials.in.preg-
nant.animals.and.nanomaterial-induced.neurotoxicity.in.their.offspring.after.birth..Mice.
were.maternally.exposed.to.TiO 2 .nanoparticles.during.pregnancy..The.results.showed.that.
nanoparticles.were.detected.in.the.brain.and.testis,.and.that.damaged.cells.and.disrupted.
normal.function.of.the.brain.and.male.genitals.were.observed.after.dissecting.the.samples.
of.offspring.taken.6.weeks.after.birth.(Takeda.et.al..2011).
Until.now,.only.minimal.research.papers.have.been.published.in.evaluating.the.toxic-
ity.of.nanomaterials.on.the.reproductive.system..Considering.the.highly.diverse.physico-
chemical. characteristics. of. nanomaterials. and. the. multiple. exposure. routes. in. humans,.
further.studies.on.the.reproductive.toxicity.of.nanomaterials,.particularly.following.long-
term.progestational.or.prenatal.exposure,.are.urgently.needed.
27.5 Conclusions and Perspectives
This.chapter.provides.an.overview.of.the.properties.of.nanomaterials.and.the.associated.
adverse.effects.in.vivo..One.of.the.essential.steps.in.the.ield.of.nanotechnology.is.to.know.
and. identify. the. hazardous. potential. of. nanomaterials.. The. following. improvement. of.
our. understanding. of. the. nanotoxicity. mechanisms. will. enable. a. safer. development. of.
nanotechnology. in. the. future.. However,. there. are. many. challenges. ahead. that. must. be.
overcome..The.complexities.of.nanoparticle.properties.require.more.delicate.analysis.and.