Environmental Engineering Reference
In-Depth Information
9
Toxicologyand
RiskAssessment
Chris E. Mackay and Jane Hamblen
AMECEarth&Environmental
Contents
9.1. Risk.Assessment.and.Nanomaterials........................................................... 194
9.1.1. Effects.of.Steric.Hindrance.............................................................. 194
9.1.2. Inlammatory.and.Immune-Based.Mechanisms.............................. 195
9.1.3. Critical.Variables.............................................................................. 195
9.2. Exposure.and.Effects.through.Ingestion..................................................... 196
9.2.1. Diffusion........................................................................................... 196
9.2.2. Endocytosis....................................................................................... 199
9.3. Exposure.and.Effects.through.Dermal.Absorption.....................................200
9.4. Exposure.and.Effects.through.Inhalation.................................................... 201
9.4.1. Mechanisms.for.Adsorption.and.Removal....................................... 201
9.4.2. Case.Study:.Inhalation.of.Carbon.Nanotubes.................................. 205
9.4.2.1. Pulmonary.Toxicology........................................................ 205
9.4.2.2. Risk.Assessment................................................................. 207
9.6. Known.Toxicity.of.Nanomaterials...............................................................209
9.7. Conclusions.................................................................................................. 220
9.8. List.of.Symbols............................................................................................ 220
References............................................................................................................... 221
Toxicological.risk.assessment,.a.common.tool.in.regulatory.science,.projects.or.char-
acterizes.the.potential.and.extent.for.a.given.situation.to.result.in.a.deined.adverse.
effect.. It. usually. involves. a. consideration. of. an. exposure. rate,. which. is. then. com-
pared.to.a.rate.related.to.a.given.toxic.response..Risk,.then,.is.quantiied.based.on.
the.possibility.or.probability.of.the.exposure.rate.meeting.or.exceeding.the.rate.that.
causes.toxicity.
Both.exposure.and.response.depend.on.an.agent's.chemistry.relative.to.its.envi-
ronmental.transport,.distribution,.and.fate.within.the.target.organism.(pharmacoki-
netics),.and.its.ability.to.elicit.an.adverse.response.at.one.or.more.sites.or.receptors.
(activity)..Any.change.in.the.chemical.disposition.of.an.agent.that.affects.exposure,.
pharmacokinetics,.or.activity.inevitably.will.alter.the.projections.of.potential.adverse.
effect.and.thereby.the.risk.
