Environmental Engineering Reference
In-Depth Information
The.toxicity.information.on.these.MSDSs.appears.to.be.based.on.the.character-
istics.of.bulk.iron.or.iron.oxides,.and.other.constituents.or.characteristics.(e.g.,.pH).
of.the.material.
Do.the.beneits.of.using.this.technology.outweigh.the.risks?.Gaps.in.the.expo-
sure.pathway.between.the.injection.of.nZVI.and.potential.receptors.mean.that.we.
cannot.completely.“connect.the.dots”.to.deinitively.determine.a.hazard:
•
Because.some.nZVI.products.may.be.shipped.as.a.slurry.with.pH.ca..12,.
risks.can.result.from.handling.highly.caustic.materials..Workers.can.man-
age.if.not.eliminate.the.risks.from.exposure.to.nZVI.reagents.using.appro-
priate.precautions.in.the.ield.and.personal.protective.equipment.
nZVI.tends.to.react.and.agglomerate.readily,.limiting.—.but.not.eliminat-
ing. —. the. potential. for. nZVI. to. persist. indeinitely. and,. for. example,. be.
inadvertently.taken.up.in.a.drinking.water.supply..Modiications.to.nZVI.
reagents.to.increase.their.mobility.and.persistence.in.groundwater.increase.
the.potential.for.nZVI.to.move.beyond.a.treatment.zone.
nZVI. is. used. at. a. limited. number. of. contaminated. sites;. and. because. the.
groundwater.is.contaminated,.exposure.to.the.groundwater.should.be.limited.
If. exposure. occurs,. some. studies. have. shown. potential. effects. on. human.
cells..Laboratory.tests,.as.described.above,.have.shown.that.glial.cells.can.
engulf. nZVI,. and. nZVI. can. then. stimulate. oxidative. stress.. However,. the.
human.body.may.limit.the.transport.of.nanoparticles.to.the.brain..Nanoparti-
cles.generally.cannot.cross.a.healthy.blood-brain.barrier..Some.nanoparticles.
may.be.able.to.migrate.to.the.brain.via.the.olfactory.nerves.upon.inhalation.
[27].. As. described. above,. screening. tests. for. Fe
2
O
3
. on. a. human. cell. line.
showed.increased.toxicity.relative.to.iron.ions,.with.a.lethal.dose.at.7.5.mg/L..
The.authors.cautioned,.however,.that.the.validity.of.
in vitro
.results.for.
in vivo
.
situations.is.very.limited.and.also.recommended.further.research.
•
•
•
As.with.any.conclusion.drawn.from.preliminary.data,.this.interpretation.should.be.
revisited.as.additional.studies.are.performed.
Absent.an.ability.to.“connect.the.dots,”.some.parties.continue.to.use.nZVI..The.
U.S.. Environmental. Protection. Agency. (EPA). sponsors. research. into. and. the. use.
of.nZVI.at.hazardous.waste.sites,.as.discussed.for.one.case.study.below..Others.are.
more.cautious..In.2007,.DuPont.evaluated.the.possible.risks.of.using.nZVI.in.envi-
ronmental.remediation.[28]..(See.Chapter.11.for.more.information.).They.concluded.
that.“DuPont.would.not.consider.using.this.technology.at.a.DuPont.site.until.the.end.
products.of.the.reactions.following.injection,.or.following.a.spill,.are.determined.and.
adequately.assessed…..DuPont.will.monitor.the.status.of.this.technology.to.review.
and.update.the.decision.as.additional.information.becomes.available.”.Speciic.con-
cerns.included:
•
Possible.ire.hazard.from.nZVI.dried.slurry.and.any.materials.used.to.clean.
up.a.spill;.the.potential.should.be.determined.and.an.appropriate.warning.
included.in.the.MSDS.
