Nanotoxicity - The Nanobiotechnology - page 609

particulates,.the.deeper.they.can.travel.into.a.lung..It.has.been.proven.that.PM 2.5 .particles.
can.reach.the.alveoli,.and.PM 0.1 .particles.mainly.deposit.in.the.alveolar.region.(Fahmy.
et.al..2010,.Yacobi.et.al..2007).
Many.epidemiologic.and.clinical.studies.have.linked.elevated.concentrations.of.ambient.
ultraine. particles. (nanoparticles). to. adverse. health. effects.. A. well-known. accident.
reported. by. Lee. et. al.. (1997). showed. that. three. polytetraluoroethylene. (PTFE). exposed.
workers.exhibited.acute.pulmonary.edema.resulting.in.one.fatality,.and.two.survivals.after.
medical.treatment..It.has.been.shown.that.the.fumes.they.experienced.can.be.generated.
by.heating.PTFE.in.a.tube.furnace.to.486°C..The.fumes.at.ultraine.particle.(particle.size.
approximately.16.nm).concentrations.of.50.μg/m 3 .were.extremely.toxic.to.rats.when.inhaled.
for. only. 15.min,. but. aging. of. the. fresh. fumes. for. 3.5.min. led. to. a. predicted. coagulation.
of. particles. 100.nm. or. greater. that. no. longer. caused. toxicity. in. the. exposed. animals.
(Johnston. et. al.. 2000).. Another. accident. case. describes. seven. women,. aged. 18-47. years,.
who.worked.in.a.printing.factory.in.China.and.had.various.exposures.to.nanoparticles.for.
5-13.months..This.resulted.in.two.of.the.women.dying.later.on..Pathological.examinations.
of. the. patients'. lung. tissue. displayed. nonspeciic. pulmonary. inlammation,. pulmonary.
ibrosis,.and.foreign-body.granulomas.of.pleura..Many.particles.around.30.nm.in.diameter.
were.found.in.lung.luid.and.tissue..An.associated.study.showed.that.the.symptoms.were.
caused.by.inhaling.the.fumes.produced.when.the.workers.heated.polystyrene.boards.to.
75°C-100°C..The.boards.had.previously.been.sprayed.with.a.paste.material.made.from.a.
plastic.identiied.as.a.polyacrylate.ester..Although.there.are.some.doubts.on.the.proof.of.the.
direct.cause,.it.arouses.concerns.that.long-term.exposure.to.some.nanoparticles.without.
protective.measures.may.be.related.to.serious.damage.to.human.health.(Song.et.al..2009).
As.a.stable.and.odorless.powder,.TiO 2 .is.an.important.material.widely.used.in.various.
ields..Some.inhalation.studies.have.been.conducted.to.examine.the.relationship.between.
pulmonary.responses.and.particle.size..Following.a.12.week.inhalation.study.of.rats.exposed.
to.nano-size.(20.nm).and.submicron-size.(250.nm).TiO 2 .particles,.pulmonary.inlammation.
was.observed.only.with.the.group.exposed.to.the.nano-size.TiO 2 .particles.(Dufin.et.al..
2007,.Renwick.et.al..2004)..Besides.the.particle.size,.the.aggregation.and.crystal.structure.
make.a.big.difference.with.respect.to.the.toxicity.on.the.respiratory.system.(Wang.et.al..
2008b)..The.inhalation.of.carbon.nanotubes.was.found.to.cause.injuries.to.the.pulmonary.
system..In.our.recent.study,.SWCNTs.were.used.to.test.the.pulmonary.toxicity.by.being.
intranasally. instilled. into. lungs. of. spontaneously. hypertensive. rats. (Ge. et. al.. 2011c)..
Biomarkers. of. inlammation,. oxidative. stress,. and. cell. damage. in. the. bronchoalveolar.
lavage.luid.(BALF).were.increased.signiicantly.after.24.h.post-exposure.of.SWCNTs..The.
increased.endothelin-1.levels.in.BALF.and.plasma.and.angiotensin.I.converting.enzyme.
in.plasma.suggested.endothelial.dysfunction.in.the.pulmonary.circulation.and.peripheral.
vascular. thrombosis.. It.suggests. that. respiratory.exposure.to.SWCNTs.can. induce. acute.
pulmonary. and. cardiovascular. responses.. Thus,. humans. with. existing. cardiovascular.
diseases. are. very. susceptible. to. SWCNTs. exposure.. From. the. results. of. histological.
evaluations. on. lung. tissues,. it. can. be. found. that. SWCNTs-laden. macrophages. move. to.
centrilobular. locations. and. form. multifocal. pulmonary. granulomas.. The. formation. of.
pulmonary.granuloma.lesions.appears.to.be.the.result.of.the.lung's.immune.response.to.
remove.foreign.substances.that.are.not.easily.eliminated.(Chou.et.al..2008,.Huizar.et.al..
2011).
It. has. been. found. that. nanoparticles. are. expected. to. induce. inlammatory. responses.
through. reactive. oxygen. species. (ROS). and. lead. to. the. occurrence. of. acute. respiratory.
infections,. lung. cancer,. chronic. obstructive. pulmonary. diseases,. and. cardiovascular.
diseases.. ROS. are. chemically. reactive. molecules. containing. oxygen. such. as. oxygen. ions.